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Heart, Lung and Circulation

Creatine Phosphate Administration in Cell Energy Impairment Conditions: A Summary of Past and Present Research

Open AccessPublished:March 16, 2017DOI:https://doi.org/10.1016/j.hlc.2016.12.020

      Background

      Creatine phosphate (CrP) plays a fundamental physiological role by providing chemical energy for cell viability and activity, especially in muscle tissue. Numerous pathological conditions, caused by acute or chronic ischaemic situations, are related to its deficiency. For these reasons, it has been used as a cardioprotective agent in heart surgery and medical cardiology for many years.

      Objective

      This article gives a brief overview of the main characteristics of exogenous CrP.

      Methods

      Previous review articles on CrP were screened for relevant information and references. Results from selected studies were reviewed and classified according to the topics in this review article and provided further interesting information on the pharmacological role of this molecule.

      Results

      Besides CrP’s well known cell energy and function restoring properties, new evidence is emerging regarding its antioxidant and anti-apoptotic properties. Use of CrP is well established clinically as an intraoperative and perioperative adjuvant in heart operations (valve replacement, coronary artery bypass grafting, congenital heart defect repair), and as an additional agent in medical cardiology therapy for acute myocardial infarction and acute and chronic heart failure. In particular, there are promising potential new CrP uses in neurology, such as in cerebral ischaemia and hypoxic ischaemic encephalopathy.

      Conclusions

      This review article describes the role of CrP treatment in cardiological indications, such as cardioprotection in cardioplegia and in myocardiopathies of various etiopathogenesis, as well as in other clinical indications such as skeletal muscle rehabilitation and neurological conditions.

      Keywords

      Introduction

      Eggleton (1927) isolated creatine phosphate (CrP)
      2-[methyl-[(E)-N'-phosphonocarbamimidoyl]amino]acetic acid (IUPAC).
      in animal muscle tissue [
      • Eggleton P.T.
      • Eggleton G.P.
      The Inorganic Phosphate and a Labile Form of Organic Phosphate in the Gastrocnemius of the Frog.
      ]. However, subsequent advances in biochemistry showed that it was also biosynthesised in humans.
      Creatine is phosphorylated into CrP in peripheral tissues by the enzymatic action of creatine kinase (CK) through the following reversible reaction: Creatine (Cr) + ATP (adenosine triphosphate) ⇔ H+ + CrP + ADP (adenosine diphosphate). Muscle tissue contains about 90% of all the creatine phosphate found in the organism [
      • Walker J.B.
      Creatine: biosynthesis, regulation, and function.
      ].
      Cain and Davies (1962) inhibited CK in experimental models and observed that ATP levels rapidly decreased to the point that muscle contractions could no longer occur owing to the lower supply of this substance in the actomyosin contractile process [
      • Cain D.F.
      • Davies R.E.
      Breakdown of adenosine triphosphate during a single contraction of working muscle.
      ]. This confirmed that the CrP/CK system is fundamental in promoting rapid synthesis of ATP, which is particularly important in situations of high metabolic demand.
      Gudbjarnason (1970) reported that high-energy phosphate (HEP) compounds, such as ATP and CrP are rapidly depleted [
      • Gudbjarnason S.
      Functional compartmentation of ATP and creatine phosphate in heart muscle.
      ] during ischaemia. Moreover, altered HEP metabolism has been seen in different experimental models of cardiac pathology [
      • Pool P.E.
      • Spann J.F.
      • Buccino R.A.
      • Sonnenblick E.H.
      • Braunwald E.
      Myocardial high-energy phosphate stores in cardiac hypertrophy and heart failure.
      ], including human cardiac pathology [
      • Hardy C.J.
      • Weiss R.G.
      • Bottomley P.A.
      • Gerstenblith G.
      Altered myocardial high-energy phosphate metabolites in patients with dilated cardiomyopathy.
      ,
      • Neubauer S.
      • Horn M.
      • Pabst T.
      • Harre K.
      • Strömer H.
      • Bertsch G.
      • et al.
      Cardiac high-energy phosphate metabolism in patients with aortic valve disease assessed by 31P-magnetic resonance spectroscopy.
      ]. High-energy phosphate depletion coincides with the destruction of the sarcolemma and irreversible cell damage [
      • Anyukhovsky E.P.
      • Javadov S.A.
      • Preobrazhensky A.N.
      • Beloshapko G.G.
      • Rosenshtraukh L.V.
      • Saks V.A.
      Effect of phosphocreatine and related compounds on the phospholipid metabolism of ischemic heart.
      ].
      Jun et al. (2014) also observed altered HEP metabolism in cerebral ischaemia. They revealed a depletion in ATP and CrP in the cerebral cortex and hippocampus following a prolonged cardiac arrest and ischaemic condition [
      • Jun J.
      • Xiangshao F.
      • Yue F.
      • Wen X.
      • Longyuan J.
      • Zitong H.
      Impaired Cerebral Mitochondrial Oxidative Phosphorylation Function in a Rat Model of Ventricular Fibrillation and Cardiopulmonary Resuscitation.
      ].
      The aim of this review is to describe the current therapeutic indications of CrP, and new prospects for CrP use in heart and brain diseases with impaired cell energy metabolism.

      Biological Activity of CrP

      The CrP Shuttle

      Creatine phosphate plays an essential role in all human tissues with high-energy requirements (heart, skeletal muscle, brain). Although the ultimate energy compound used for muscle contraction is ATP, the primary energy transport medium is CrP [
      • Bessman S.
      A physiological view of the creatine-phosphate shuttle, exercise, and protein synthesis.
      ], which acts as a shuttle molecule between ATP production and utilisation sites [
      • Bessman S.P.
      The creatine-creatine phosphate energy shuttle.
      ]. Adenosine triphosphate is initially produced in the cell mitochondrion and the site of ATP utilisation in muscle contraction is the myofibril. However, since the direct transport of ATP molecules across the mitochondrial membranes is hindered, the chemical energy is moved through Cr phosphorylation into CrP: this is the “CrP shuttle”. Creatine receives a high-energy phosphate group from ATP in the mitochondrial membrane, and then donates it to ADP in the sarcoplasm (i.e. ATP + Cr) to make muscle contractions possible. Adenosine triphosphate and CrP availability is regulated through the “CrP shuttle” on the basis of tissue energy requirements [
      • Bessman S.P.
      The creatine-creatine phosphate energy shuttle.
      ].
      Adenosine triphosphate is required in the heart for cell viability and the myocardial pump function. Since there is very little ATP in the heart compared with demand, myocardial cells must continuously resynthesise it to maintain cell viability and contractile function.

      CrP Reduction in Cells: Physiopathological Aspects

      Several studies in the history of cardiology have focussed on the role of altered HEP metabolism, firstly in experimental heart disease models and then on humans with heart diseases.
      Preliminary experiments by Hearse (1979) [
      • Hearse D.
      Oxygen deprivation and early myocardial contractile failure: a reassessment of the possible role of adenosine triphosphate.
      ] and Whitman (1985) [
      • Whitman G.
      • Kieval R.
      • Seeholzer S.
      Recovery of left ventricular function after graded cardiac ischemia as predicted by myocardial P-31 nuclear magnetic resonance.
      ], with isolated hypoxic rat hearts and ischaemic rabbit hearts respectively, revealed a decrease in myocardial CrP, contractile activity and slower fall in ATP. More recently, Ye et al. (2001) observed a decrease in CrP/ATP ratio and creatine kinase isoenzyme release in a porcine model of cardiac hypertrophy and failure, in keeping with the degree of cardiac hypertrophy [
      • Ye Y.
      • Gong G.
      • Ochiai K.
      • Liu J.
      • Zhang J.
      High-energy phosphate metabolism and creatine kinase in failing hearts: a new porcine model.
      ].
      These experimental data have been confirmed in human pathology. Hardy et al. (1991) observed a decrease in the myocardial CrP/ATP ratio in patients with dilated-cardiomyopathy [
      • Hardy C.J.
      • Weiss R.G.
      • Bottomley P.A.
      • Gerstenblith G.
      Altered myocardial high-energy phosphate metabolites in patients with dilated cardiomyopathy.
      ]. Myocardial CrP/ATP ratio was also shown to be a significant independent predictor of cardiovascular mortality (5% with CrP/ATP ratio >1,6; 10% if CrP/ATP ratio is <1.6) in a multivariate analysis of patients with heart failure [
      • Neubauer S.
      • Horn M.
      • Pabst T.
      • Harre K.
      • Strömer H.
      • Bertsch G.
      • et al.
      Cardiac high-energy phosphate metabolism in patients with aortic valve disease assessed by 31P-magnetic resonance spectroscopy.
      ].
      Neubauer et al. (1992) reported that a decrease in myocardial CrP/ATP ratio correlates with the severity of heart failure, and that the CrP/ATP ratio increases after CrP treatment leading to improvement in the patient’s New York Heart Association (NYHA) status [
      • Neubauer S.
      • Krahe T.
      • Schindler R.
      • Horn M.
      • Hillenbrand H.
      • Entzeroth C.
      • et al.
      31P magnetic resonance spectroscopy in dilated cardiomyopathy and coronary artery disease. Altered cardiac high-energy phosphate metabolism in heart failure.
      ].
      New studies performed with biochemical heart failure markers, like plasma B-type natriuretic peptide level [
      • Chida K.
      • Otani H.
      • Kohzuki M.
      • Saito H.
      • Kagaya Y.
      • Takai Y.
      • et al.
      The relationship between plasma BNP level and the myocardial phosphocreatine/adenosine triphosphate ratio determined by phosphorus-31 magnetic resonance spectroscopy in patients with dilated cardiomyopathy.
      ], have demonstrated that the CrP/ATP ratio negatively correlates with the severity of heart failure.
      Lastly, brain tissue is also susceptible to ischaemic injury due to its high metabolic rate, limited intrinsic energy stores, and critical dependence on the aerobic glucose metabolism [
      • Lee J.M.
      • Grabb M.C.
      • Zipfel G.J.
      • Choi D.W.
      Brain tissue responses to ischemia.
      ].
      Jun et al. (2014) demonstrated in animals that partial depletions of ATP and CrP developed in the cerebral cortex and hippocampus after prolonged ischaemia-inducing cardiac arrest, thus showing the importance of adequate amounts of CrP to avoid brain damage after ischaemia/reperfusion [
      • Jun J.
      • Xiangshao F.
      • Yue F.
      • Wen X.
      • Longyuan J.
      • Zitong H.
      Impaired Cerebral Mitochondrial Oxidative Phosphorylation Function in a Rat Model of Ventricular Fibrillation and Cardiopulmonary Resuscitation.
      ].

      The Use of Exogenous CrP in Preventing Cell Energy Impairment

      Creatine phospate is the first molecule to be depleted in ischaemia, anoxia and toxic cardiomyopathies [
      • Reimer K.H.
      • Jennings R.B.
      • et al.
      Myocardial ischemia, hypoxia and infarction.
      ,
      • Jennings R.B.
      • Murry C.E.
      • Steenbergen C.
      • Reimer K.A.
      Development of cell injury in sustained acute ischemia.
      ], whereas in stress conditions, such as hypoxia, the myocardial cells increase their uptake of exogenous CrP [
      • Breccia A.
      • Fini A.
      • Girotti S.
      • Gattavecchia E.
      Intracellular distribution of double-labelled creatine phosphate in the rabbit myocardium.
      ,
      • Fini A.
      • Breccia A.
      • Girotti S.
      Distribuzione intracellulare della 14C-creatina 32P-fosfato nel miocardio di coniglio.
      ].
      This suggests that extracellular administration of CrP may compensate for the energy deficiency [
      • Angelucci L.
      • Boldrini R.
      • Mascitelli-Coriandoli E.
      Effect of creatine phosphate administration of the cardiac adenosine triphosphate of thyroxinized rats.
      ]. Several experimental studies have, therefore, been carried out to evaluate the effects of exogenous CrP in cell energy impairment conditions.
      Creatine phosphate has been shown to inhibit adenosine monophosphate (AMP) catabolism enzymes: AMP deaminase and 5′-nucleotidase [
      • Saks V.A.
      • Dzhaliashvili I.V.
      • Konorev E.A.
      • Strumia E.
      Molecular cellular aspects of the cardio protective mechanism of phosphocreatine.
      ]. If 5′-nucleotidase activity is inhibited, the adenine structure is preserved in the form of AMP, and since the adenylate kinase reaction in ADP formation is reversible, ADP (and ATP) still forms.
      Creatine phosphate also preserves the adenine nucleotide pool by working on de novo synthesis. Creatine phosphate removes ADP’s inhibition of phosphoribosylpyrophosphate (PRPP) synthase, the enzyme which catalyses the formation of PRPP from ribose 5-phosphate + ATP, leading to the neo-synthesis of adenine nucleotides [
      • Saks V.A.
      • Dzhaliashvili I.V.
      • Konorev E.A.
      • Strumia E.
      Molecular cellular aspects of the cardio protective mechanism of phosphocreatine.
      ].
      One in vitro and in vivo study in the ischaemic myocardium [
      • Saks V.A.
      • Kapelko V.I.
      • Konorev E.A.
      • Kupriyanov V.V.
      • Lakomkin V.L.
      • Steinschneider A.Y.
      • et al.
      Further studies on the role of ATP and phosphocreatine in cardiac cells. Biochemical basis of pharmacological action of phosphocreatine.
      ] showed that a 10 mmol concentration of exogenous CrP reduced the accumulation of lysophosphatidylcholine and lysophosphatidylethanolamine in cells, thus stabilising the myocardial cell membranes and preventing arrhythmias.
      Furthermore, CrP is able to protect membrane structure through direct interaction with membrane phospholipids. In this electrical interaction, endogenous and exogenous CrP behaves like a zwitterion [
      • Saks V.A.
      • Dzhaliashvili I.V.
      • Konorev E.A.
      • Strumia E.
      Molecular cellular aspects of the cardio protective mechanism of phosphocreatine.
      ]. Its opposite charges interact with the charged phospholipids located on both sides of the sarcolemma [
      • Post J.A.
      • Langer G.A.
      • Op den Kamp J.A.
      • Verkleij A.J.
      Phospholipid asymmetry in cardiac sarcolemma. Analysis of intact cells and “gas-dissected” membranes.
      ] leading to sarcolemma stability.
      Creatine phosphate’s membrane-stabilising effect is also behind its ability to protect the heart against several other kinds of damage, besides ischaemic injury, such as oxidative stress.
      Free oxygen radicals are considered the main causes of myocardial damage, especially during ischaemia and reperfusion [
      • Piper H.M.
      Pathophysiology of severe ischemic myocardial injury.
      ]. Zucchi et al. (1989) showed that the overproduction of malonylaldehyde (MDA), caused by free radicals, was significantly lower in the presence of a low concentration of CrP [
      • Zucchi R.
      • Poddighe R.
      • Limbruno U.
      • Mariani M.
      • Ronca-Testoni S.
      • Ronca G.
      Protection of isolated rat heart from oxidative stress by exogenous CrP.
      ]. Moreover, Conorev et al. (1991) elucidated the mechanism of CrP antioxidant action, confirming that CrP acts on the lipid bilayer by arranging membrane phospholipids in the membrane structure [
      • Conorev E.A.
      • Sharov V.G.
      • Saks V.A.
      Improvement in contractile recovery of isolated rat heart after cadioplegic ischemic arrest with endogenous phosphocreatine: Involvement of antiperoxidative effect.
      ].
      Zhang et al. (2015) showed that CrP administration reduced the release of certain inflammatory markers, such as serum creatine kinase (CK), myeloperoxidase (MPO) and lactate dehydrogenase (LDH), in ischaemia/reperfusion (I/R) experiments and that these decreases were consistent with the decrease in the myocardial infarct size [
      • Zhang W.
      • Zhang H.
      • Xing Y.
      Protective effects of phosphocreatine administered post- treatment combined with ischemic post-conditioning on rat hearts with myocardial ischemia/reperfusion injury.
      ].
      Azova et al. (2015) investigated the anti-apoptotic effect of CrP in the cardiomyocytes of mice with spontaneous hypertension [
      • Azova M.M.
      • Blagonravov M.L.
      • Frolov V.A.
      Effect of phosphocreatine and ethylmethylhydroxypyridine succinate on the expression of bax and bcl-2 proteins in left-ventricular cardiomyocytes of spontaneously hypertensive rats.
      ]. Creatine phosphate was seen to reduce apoptosis significantly by decreasing pro-apoptotic protein (Bax) and increasing anti-apoptotic protein (Bcl-2) compared to the anti-apoptotic agent ethyl-methylhydroxypyridine succinate.
      The cardioprotective effects of CrP on myocardial cell ultrastructure and calcium-sensing receptor (CaSR) expression following an acute high-level spinal cord injury (SCI) associated with a decline in cardiac output [
      • Chen H.
      • Gong C.
      • Ma C.
      • Zhang X.
      • Xu L.
      • Lin C.
      Cardio protective effects of phosphocreatine on myocardial cell ultrastructure and calcium-sensing receptor expression in the acute period following high-level spinal cord injury.
      ] was recently investigated in a Sprague-Dawley rat model: CrP reduced myocardial tissue necrosis and preserved the normal metabolic energy balance. Creatine phosphate treatment also reduced the increase in pro-apoptotic CaSR, and this may be central to the mechanism by which CrP reduces apoptosis in myocardial tissues following SCI and other traumatic injuries.

      Clinical Applications of CrP in Cardiology

      The protective action of exogenous CrP in heart surgery and medical cardiology has been observed in numerous controlled clinical trials by assessing different clinical, haemodynamic and ultra-structural parameters.

      CrP Administration in Heart Surgery

      A key component in the development of myocardial ischaemia during surgical procedures is an inadequate cellular energy supply, consequent to HEP depletion. Since it plays a critical role in maintaining cell viability and in post-ischaemic contractile function recovery, its preservation is a primary objective in any procedure designed to reduce ischaemic injury.
      The cardioprotective effects of adding CrP to cardioplegic solutions (at a concentration of 10 mmol/L) and/or administering it during the perioperative period have been extensively studied in different kinds of heart surgery, including valve replacement (VR), coronary artery bypass grafting (CABG) and the repair of congenital heart defects. The effects are summarised in Table 1.
      Table 1Clinical effects of CrP in heart surgery.
      CrP UseClinical OutcomeReferences
      With cardioplegia alone (VR, CABG, CHD) or in the perioperative period as well; only in the perioperative period (CABG)
      • Improvement in cardiac high energy phosphate tissue levels and cell structures
      • Improvement in spontaneous recovery of sinus rhythm after declamping
      • Reduction in direct-current shocks and total pulses for defibrillation
      • Reduction in use and doses of inotropic drugs
      • Reduction in arrhythmic complications
      • Reduction in third-degree atrioventricular blocks
      • Reduction in myocardial enzyme release (troponins, CPK and MB- CPK)
      • Semenovsky M.L.
      • Shumakov V.I.
      • Sharov V.G.
      • Mogilevsky G.M.
      • Asmolovsky A.V.
      • Makhotina L.A.
      • et al.
      Protection of ischemic myocardium by exogenous phosphocreatine. II. Clinical, ultrastructural, and biochemical evaluations.
      ,
      • D’alessandro L.C.
      • Cini R.
      • Pucci A.
      • Stazi G.
      Protezione miocardica: uso del creatin fosfato addizionato alla soluzione cardioplegica. Heart Surg 1987.
      ,
      • Chambers D.J.
      • Braimbridge M.V.
      • Kosker S.
      • Yamada M.
      • Jupp R.A.
      • Crowther A.
      Creatine phosphate (Neoton) as an additive to St. Thomas’ Hospital cardioplegic solution (Plegisol). Results of a clinical study.
      ,
      • Cossolini M.
      • Sonzogni V.
      • Di Dedda G.
      • Fruga F.
      • Pansera C.
      • Pirola C.
      • et al.
      Paediatric cold heart surgery: experience with creatine phosphate added to cardioplegic solution.
      ,
      • Zhidkov I.L.
      • Ivanov V.A.
      • Kozhevnikov V.A.
      • Charnaia M.A.
      • Mukhamedzianova A.R.
      • Trekova N.A.
      Intraoperative myocardial protection with extracellular cardioplegic solutions in patients with cardiac valve diseases.
      ,
      • Tao W.
      • Shouxian L.
      Study of the myocardial effect of creatine phosphate cardioplegia.
      ,
      • Guo-Han C.
      • Jian-Hua G.
      • Xuan H.
      • Jinyi W.
      • Rong L.
      • Zhong-Min L.
      Role of creatine phosphate as a myoprotective agent during coronary artery bypass graft in elderly patients.
      ,
      • Cisowski M.
      • Bochenek A.
      • Kucewicz E.
      • Wnuk-Wojnar A.M.
      • Morawski W.
      • Skalski J.
      • et al.
      The use of exogenous creatine phosphate for myocardial protection in patients undergoing coronary artery bypass surgery.
      ,
      • Donegani E.
      • Villani M.
      • Ottino G.
      Protezione miocardica in cardiochirurgia con creatina fosfato nel periodo perioperatorio.
      ,
      • Pagani L.
      • Musiani A.
      The use of systemic phosphocreatine in heart surgery.
      ,
      • Hapy H.
      • Filippovskaya J.
      • Hapy I.
      • Lopatin A.
      Evaluating the effectiveness of Neoton in the postoperative period.
      ,
      • Barayev O.V.
      • Zotov A.S.
      • Ilyin M.V.
      • Smirnova V.P.
      • Tsybin N.V.
      Results of exogenous phosphocreatine use in coronary artery bypass surgery using extracorporeal circulation system in patients with reduced myocardial flow reserves.
      Valve replacement (VR); coronary artery bypass grafting (CABG); repair of congenital heart defects (CHD), creatine phosphokinase (CPK), creatine phosphokinase-MB (CPK-MB).

      CrP Administration in Cardioplegia

      The first human trial, conducted by Semenovsky et al. (1987), showed that adding CrP to cardioplegic solution resulted in a more efficient restoration of sinus rhythm and less need for defibrillation [
      • Semenovsky M.L.
      • Shumakov V.I.
      • Sharov V.G.
      • Mogilevsky G.M.
      • Asmolovsky A.V.
      • Makhotina L.A.
      • et al.
      Protection of ischemic myocardium by exogenous phosphocreatine. II. Clinical, ultrastructural, and biochemical evaluations.
      ]. Moreover, the concentration of high-energy compounds in CrP-treated patients remained at preoperative levels. Similar results were obtained by D’Alessandro et al. (1987), who also reported significant reductions in inotropic drug support and frequency of postoperative electrocardiographic abnormalities in the CrP-treated group [
      • D’alessandro L.C.
      • Cini R.
      • Pucci A.
      • Stazi G.
      Protezione miocardica: uso del creatin fosfato addizionato alla soluzione cardioplegica. Heart Surg 1987.
      ].
      Chambers et al. (1991) studied myocardial protection with exogenous CrP by measuring birefringence changes in response to ATP and calcium using polarised microscopy [
      • Chambers D.J.
      • Braimbridge M.V.
      • Kosker S.
      • Yamada M.
      • Jupp R.A.
      • Crowther A.
      Creatine phosphate (Neoton) as an additive to St. Thomas’ Hospital cardioplegic solution (Plegisol). Results of a clinical study.
      ]. Intraoperative biopsies were taken from both ventricles of (mainly) coronary artery bypass patients for the birefringence assessment of myocardial contractility preservation. Patients who received 10 mmol/L of CrP in their cardioplegic solution showed significantly higher post-ischaemic contractility in the endocardium and right ventricle than controls.
      Cossolini et al. (1993) carried out a study in neonates and children (9 days to 13 years) undergoing open-heart surgery for congenital heart disease [
      • Cossolini M.
      • Sonzogni V.
      • Di Dedda G.
      • Fruga F.
      • Pansera C.
      • Pirola C.
      • et al.
      Paediatric cold heart surgery: experience with creatine phosphate added to cardioplegic solution.
      ]. After reperfusion, the CrP-treated group showed a significantly higher spontaneous recovery of sinus rhythm, fewer DC-shocks to convert to sinus rhythm, and less A-V blocks than controls. Ventricular fibrillation and other postoperative arrhythmias were significantly less frequent. The CrP-treated group also required significantly lower doses of inotropic drugs.
      Zhidkov et al. (2007) assessed the intraoperative myocardial protection of different cardioplegic solutions in heart valve patients [
      • Zhidkov I.L.
      • Ivanov V.A.
      • Kozhevnikov V.A.
      • Charnaia M.A.
      • Mukhamedzianova A.R.
      • Trekova N.A.
      Intraoperative myocardial protection with extracellular cardioplegic solutions in patients with cardiac valve diseases.
      ]. The study reported that the administration of Consol cardioplegic solution with CrP and insulin added (Consol MF) showed a more effective cardioprotective activity than St. Thomas’ cardioplegic solution. Moreover, Consol MF solution was more effective than Consol cardioplegic solution alone in reducing cardiac arrests due to fibrillation and the inotropic support need, decreasing arrhythmias, and increasing the spontaneous recovery of cardiac activity.
      Tao and Shoxian (2001) showed that the serum levels of enzymes (CK, CK-MB, LDH, HBDH and AST) rose less postoperatively in patients who received cardioplegic solution with CrP added during open-heart surgery. They decreased faster than in controls suggesting lighter myocardial damage and a faster recovery of myocardial injury in CrP-treated patients [
      • Tao W.
      • Shouxian L.
      Study of the myocardial effect of creatine phosphate cardioplegia.
      ].
      These clinical results have recently been confirmed by Guo-han et al. (20013), who evaluated the myocardial protective effect of exogenous CrP added to cardioplegic solution in elderly patients undergoing CABG by measuring cardiac injury markers before and after aortic clamping [
      • Guo-Han C.
      • Jian-Hua G.
      • Xuan H.
      • Jinyi W.
      • Rong L.
      • Zhong-Min L.
      Role of creatine phosphate as a myoprotective agent during coronary artery bypass graft in elderly patients.
      ]. There was a lower serum release of CK, CK-MB, lactate dehydrogenase (LDH), cardiac troponin T and malonyldehyde (MDA) in CrP-treated patients (Figure 1). On the other hand, higher serum levels of superoxide dismutase (SOD) were preserved in the CrP-treated group (Figure 2). Moreover, studying myocardium ultrastructure under an electron microscope has shown that the mitochondria matrix is only preserved in CrP-treated patients (Figure 3).
      Figure 1
      Figure 1Differences in MDA between CrP-treated patients and controls patients undergoing CABG.
      Reproduced with permission from Guo-Han C, Jian-Hua G, Xuan H, Jinyi W, Rong L, Zhong-Min L. Role of creatine phosphate as a myoprotective agent during coronary artery bypass graft in elderly patients. Coron Artery Dis. 2013;24(1):48–53
      Figure 2
      Figure 2Difference in SOD between CrP-treated patients and controls patients undergoing CABG.
      Reproduced with permission from Guo-Han C, Jian-Hua G, Xuan H, Jinyi W, Rong L, Zhong-Min L. Role of creatine phosphate as a myoprotective agent during coronary artery bypass graft in elderly patients. Coron Artery Dis. 2013;24(1):48–53
      Figure 3
      Figure 3Myocardial ultrastructure (mitochondria) before aortic declamping in control group (left) and in CrP-treated group (right) in patients undergoing CABG.
      Reproduced with permission from Guo-Han C, Jian-Hua G, Xuan H, Jinyi W, Rong L, Zhong-Min L. Role of creatine phosphate as a myoprotective agent during coronary artery bypass graft in elderly patients. Coron Artery Dis. 2013;24(1):48–53

      Perioperative Administration of CrP in Coronary Artery Bypass Grafting

      The cardioprotective effects of perioperative CrP administration have been studied in CABG patients.
      In a study by Cisowski et al. (1996), patients received CrP-enriched or simple St Thomas’ cardioplegic solution during surgery [
      • Cisowski M.
      • Bochenek A.
      • Kucewicz E.
      • Wnuk-Wojnar A.M.
      • Morawski W.
      • Skalski J.
      • et al.
      The use of exogenous creatine phosphate for myocardial protection in patients undergoing coronary artery bypass surgery.
      ]. The CrP-treated group also received a daily dose of 6 g of CrP by intravenous infusions during the three days before surgery and 4 g of CrP a day during the two days after. The CrP-treated patients required fewer and lower energy DC-shocks to restore cardiac function after CABG, had fewer ventricular arrhythmias in the early postoperative period, required less inotropic support and revealed a lower degree of sarcolemma damage in myocardial biopsies.
      In a study by Donegani et al. (1989), patients received 2 g of CrP by intravenous infusion before starting the surgical procedures, in the period immediately after aorta declamping and for two days following the operation (4 g/day) [
      • Donegani E.
      • Villani M.
      • Ottino G.
      Protezione miocardica in cardiochirurgia con creatina fosfato nel periodo perioperatorio.
      ]. The CrP-treated group showed a significantly better recovery of spontaneous sinus rhythm, and A-V blocks were only observed in controls. During the postoperative period, the observed trend in ECG ischaemic score and the need for inotropic support was also better in the CrP-treated group.
      Similar results were obtained in a study by Pagani and Musiani (1992) where CrP was infused intravenously before and after cardiac arrest [
      • Pagani L.
      • Musiani A.
      The use of systemic phosphocreatine in heart surgery.
      ]. The CrP-treated group showed easier recovery of sinus rhythm, a lower incidence of arrhythmias, and a significantly lower release of cardiac enzymes (CPK-MB; CPK).
      Hapy et al. (2011) investigated the administration of 4 g of CrP daily during a two-day postoperative period after heart surgery [
      • Hapy H.
      • Filippovskaya J.
      • Hapy I.
      • Lopatin A.
      Evaluating the effectiveness of Neoton in the postoperative period.
      ]. Echocardiographic assessment during the early postoperative period (one day after surgery) in coronary artery disease patients revealed better myocardial contractility normalisation and a lower incidence of arrhythmias in the CrP-treated group than in controls (two-fold less). Lastly, a larger number of CrP-treated patients were extubated and discharged from the intensive care unit in the first 12 hours after surgery than controls.
      More recently, Barayev et al. (2012) investigated the use of exogenous CrP to reduce the frequency and severity of perioperative ischaemia and prevent arrhythmias in the perioperative period in three different groups of patients undergoing CABG [
      • Barayev O.V.
      • Zotov A.S.
      • Ilyin M.V.
      • Smirnova V.P.
      • Tsybin N.V.
      Results of exogenous phosphocreatine use in coronary artery bypass surgery using extracorporeal circulation system in patients with reduced myocardial flow reserves.
      ]. One group of patients received 2.5 g of CrP/L in their cardioplegic solution, followed by i.v. injection of 4 g a day during the one to three-day post-surgery period, depending on the severity of myocardial injury. A second group received 4 g of CrP immediately before extracorporeal circulation, followed by i.v. injection of 4sg a day during the one to three-day post-surgery period. A control group did not receive CrP. The frequency of perioperative myocardial ischaemia (confirmed by ECG, echo and biochemical parameters) and inotropic support during the postoperative period were reported to be significantly lower than in controls in both CrP-treated groups. Moreover, ST segment normalisation and the frequency of spontaneous sinus rhythm recovery in the operating room were significantly higher in both CrP-treated groups.
      Since all doses of CrP administered before and after the operation (2–4 g per day for up to three days) were effective and well tolerated, with a favourable treatment risk-benefit ratio, it is advisable to use the full dose during the two to three days before and after surgery.

      CrP Administration in Acute Myocardial Infarction

      The positive effects of CrP in animal models of acute ischaemia are also observed in clinical situations. These effects are summarised in Table 2.
      Table 2Clinical effects of CrP in medical cardiology.
      CrP UseClinical OutcomeReferences
      Acute Myocardial Infarction
      • Improvement in heart muscle contraction
      • Improvement in ejection fraction, shortening fraction and haemodynamic status
      • Improvement in quality of life and functional status according to the NYHA classification
      • Improvement in ECG myocardial ischaemia scores
      • Improvement in physical performance
      • Ruda M.
      • Samarenko M.B.
      • Afonskaya N.I.
      • Saks V.
      Reduction of ventricular arrhythmias by phosphocreatine (Neoton) in patients with acute myocardial infarction.
      ,
      • Stejfa M.
      • Zeman K.
      • Groch L.
      • Marek J.
      • Komárek J.
      • Janota T.
      • et al.
      The effect of creatine phosphate (Neoton) in acute myocardial infarct (a prospective multicenter pilot study).
      ,
      • Reimers B.
      • Maddalena F.
      La fosfocreatina nell’infarto miocardico acuto: studio randomizzato multicentrico.
      ,
      • Coraggio F.
      • Spina M.
      • Scarpato P.
      • Angiulli B.
      • Catalano A.
      • Costa M.R.
      • et al.
      Analysis of phosphocreatine on the evolution of ischaemic lesions in acute myocardial infarction.
      ,
      • Cini R.
      • Stazi G.
      • Giacopino F.
      Creatinfosfato nella fase acuta dell’infarto miocardico. Risultati preliminari di uno studio clinico.
      ,
      • Raisaro A.
      • Bargiggia C.
      • Bertucci C.
      Clinical evaluation of phosphocreatine effect during acute myocardial infarction: A multicenter study.
      ,
      • Camilova U.
      • Katsenovich R.
      • Kostco S.
      Combined use of creatine phosphate and nifedipine for treatment of patients with acute myocardial infarction.
      ,
      • Perepech N.B.
      • Nedoshivin A.O.
      • Kutuzova A.E.
      Exogenous phosphocreatine in the prevention and treatment of cardiac insufficiency in patients with myocardial infarction.
      ,
      • Perepech N.B.
      • Nedoshivin A.O.
      • Nesterova I.V.
      Neoton and thrombolytic therapy of myocardial infarction.
      Chronic and Acute Heart Failure
      • Reduction in incidence of arrhythmias
      • Reduction in left-ventricular dilatation
      • Reduction in incidence of cardiac ruptures
      • Reduction in consumption of nitroglycerin
      • Reduction in myocardial enzyme release (CPK, MB-CPK, LDH)
      • Reduction in dyspnoea, pulmonary stasis, stable angina
      • Reduction in peripheral oedemas
      • Grazioli I.
      • Strumia E.
      Terapia con creatina fosfato nel paziente con insufficienza cardiaca in fase di scompenso.
      ,
      • Andreev N.
      • Andreva T.
      • Bichkov I.
      Effect of phosphocreatine in congestive heart failure.
      ,
      • Wang F.R.
      • Zheng X.
      Effects of phosphocreatine on plasma brain natriuretic peptide level and left ventricular function in patients with heart failure.
      ,
      • Ying W.
      • Chen Y.
      Efficiency of Creatine Phosphate Sodium and Hyzaar in hypertensive patients with diastolic dysfunction.
      ,
      Editorial: Skeletal muscle in heart failure.
      Creatine phosphokinase (CPK), Creatine phosphokinase-MB (CPK-MB), lactate dehydrogenase (LDH).
      In a clinical trial in patients with acute myocardial infarction (AMI), Ruda et al. (1988) described the antiarrhythmic action of CrP when intravenously administered within six hours of symptom onset (2 g i.v. bolus followed by a two-hour infusion at 4 g/h) [
      • Ruda M.
      • Samarenko M.B.
      • Afonskaya N.I.
      • Saks V.
      Reduction of ventricular arrhythmias by phosphocreatine (Neoton) in patients with acute myocardial infarction.
      ]. Twenty-four hour Holter monitoring showed a significantly lower frequency of ventricular premature beats and number of ventricular tachycardia paroxysms in the CrP-treated group than in controls.
      Similar results were observed by Stejfa et al. (1993) [
      • Stejfa M.
      • Zeman K.
      • Groch L.
      • Marek J.
      • Komárek J.
      • Janota T.
      • et al.
      The effect of creatine phosphate (Neoton) in acute myocardial infarct (a prospective multicenter pilot study).
      ]. These investigators reported a smaller number of severe forms of heart attack, as assessed by ECG monitoring, in CrP-treated patients with AMI. Holter monitoring again showed a 30–40% lower incidence of ventricular arrhythmias during the first 24 hours than in controls.
      Reimers et al. (1994) also observed markedly lower CK and MB-CK release with a more prolonged period of CrP daily infusion (4 g bolus on admission, 6 g during the following two hours and 6 g/24 h continuously infused for five days) [
      • Reimers B.
      • Maddalena F.
      La fosfocreatina nell’infarto miocardico acuto: studio randomizzato multicentrico.
      ].
      Lower enzyme release and/or a reduction in arrhythmias was also observed in CrP-treated patients in other trials. In a study by Coraggio et al. (1987), lower myocyte damage marker peaks (CK and MB-CK) were measured in patients receiving CrP [
      • Coraggio F.
      • Spina M.
      • Scarpato P.
      • Angiulli B.
      • Catalano A.
      • Costa M.R.
      • et al.
      Analysis of phosphocreatine on the evolution of ischaemic lesions in acute myocardial infarction.
      ]. Cini et al. (1987) observed a more rapid improvement in ST changes and less ventricular arrhythmias with CrP than in controls [
      • Cini R.
      • Stazi G.
      • Giacopino F.
      Creatinfosfato nella fase acuta dell’infarto miocardico. Risultati preliminari di uno studio clinico.
      ]. Raisaro et al. (1989) reported that CrP-treated patients had lower electrocardiographic and echocardiographic indices of myocardial damage than controls [
      • Raisaro A.
      • Bargiggia C.
      • Bertucci C.
      Clinical evaluation of phosphocreatine effect during acute myocardial infarction: A multicenter study.
      ]. The use of CrP during acute myocardial infarction therapy has never been associated with any significant side effects in any trial, as was also shown in a study by Camilova et al. (1991) [
      • Camilova U.
      • Katsenovich R.
      • Kostco S.
      Combined use of creatine phosphate and nifedipine for treatment of patients with acute myocardial infarction.
      ].
      Perepech et al. (1993) assessed haemodynamics and myocardial contractility in patients with macro focal myocardial infarction who received a total dose of 30 g of CrP during the six days following the disease onset, in addition to conventional therapy [
      • Perepech N.B.
      • Nedoshivin A.O.
      • Kutuzova A.E.
      Exogenous phosphocreatine in the prevention and treatment of cardiac insufficiency in patients with myocardial infarction.
      ]. Creatine phosphate was found to prevent left-ventricular dilatation and the development of congestive heart failure by decreasing pre-load, and to maintain myocardial contractility without relevant changes in haemodynamic parameters.
      In a second study, Perepech et al. (2001) confirmed the therapeutic effects of CrP administration on left ventricle systolic function in patients with AMI receiving thrombolytic therapy [
      • Perepech N.B.
      • Nedoshivin A.O.
      • Nesterova I.V.
      Neoton and thrombolytic therapy of myocardial infarction.
      ]. Thrombolytic therapy with a streptokinase preparation alone failed to arrest the progression of left ventricular dilation during the first months after AMI onset. Patients who received CrP in addition during the acute period of myocardial infarction showed no increase in the final left ventricular systolic and diastolic volumes.

      CrP Administration in Acute and Chronic Heart Failure

      The effects of CrP in patients with acute and chronic heart failure are summarised in Table 2.
      In the largest study with CrP in patients with heart failure, Grazioli et al. (1989) observed the effects of adding CrP (2 g/daily i.v. for three weeks) to conventional therapy (digitalis, diuretics, nitrates) [
      • Grazioli I.
      • Strumia E.
      Terapia con creatina fosfato nel paziente con insufficienza cardiaca in fase di scompenso.
      ]. A total of 1174 heart failure patients were randomly assigned CrP-treatment (739) or no CrP-treatment (435). This study showed that the main symptoms and signs of ischaemia (angina pectoris, need for sublingual nitroglycerin and T-wave inversion on ECG) and the incidence of ventricular premature beats improved significantly in CrP-treated patients.
      Andreev et al. (1992) examined the effects of CrP and digoxin in elderly patients with NYHA class II–III chronic heart failure with ischaemic aetiology [
      • Andreev N.
      • Andreva T.
      • Bichkov I.
      Effect of phosphocreatine in congestive heart failure.
      ]. Combined treatment resulted in an increase in the left ventricular ejection fraction, a decrease in systemic vascular resistance, and a reduction in the frequency of ventricular extra systoles and paroxysmal ventricular tachycardia. Improvements in the patients’ clinical status with a decrease in the severity of dyspnoea and frequency of angina attacks, and reduction in the need for nitroglycerin were also obtained.
      More recently, Wang et al. (2008) evaluated the effects of CrP on left ventricular function and plasma-brain natriuretic peptide release in patients with heart failure [
      • Wang F.R.
      • Zheng X.
      Effects of phosphocreatine on plasma brain natriuretic peptide level and left ventricular function in patients with heart failure.
      ]. Patients receiving 2 g of CrP once a day for 14 days showed significant improvements in their left ventricular ejection fraction, stroke volume and cardiac output compared to controls with a significant lowering in B-type natriuretic peptide levels.
      Lastly, Ying et al. (2013) compared the clinical efficacy of adding CrP (2 g/day for 14 days) to an anti-hypertensive drug, containing losartan potassium (50 mg) and hydrochlorothiazide (12.5 mg), to using the anti-hypertensive drug alone in patients with hypertensive cardiac diastolic dysfunction [
      • Ying W.
      • Chen Y.
      Efficiency of Creatine Phosphate Sodium and Hyzaar in hypertensive patients with diastolic dysfunction.
      ]. A significant reduction in blood pressure was observed in both groups after treatment. However, the combined treatment group reported better improvement in diastolic dysfunction compared to the mono-drug group.

      The Use of Exogenous CrP in Reduced Skeletal Muscle Performance

      Patients with congestive heart failure show a decrease in skeletal muscle functional capacity [
      Editorial: Skeletal muscle in heart failure.
      ,
      • Drexler H.
      • Münzel T.
      • Riede U.
      • Just H.
      Adaptive changes in the periphery and their therapeutic consequences.
      ,
      • Drexler H.
      Skeletal muscle failure in heart failure.
      ,
      • Drexler H.
      • Coats A.J.
      Explaining fatigue in congestive heart failure.
      ]. Increasing workloads in patients with mild-to-moderate congestive heart failure results in CrP depletion and a lower pH in the flexor digitorum superficialis [
      • Massie B.M.
      • Conway M.
      • Rajagopalan B.
      • Yonge R.
      • Frostick S.
      • Ledingham J.
      • et al.
      Skeletal muscle metabolism during exercise under ischemic conditions in congestive heart failure. Evidence for abnormalities unrelated to blood flow.
      ]. Lunde et al. (2001) confirmed that CrP breaks down more rapidly and intramuscular pH is lower during exercise in patients with heart failure than in healthy subjects [
      • Lunde P.K.
      • Sjaastad I.
      • Schiøtz Thorud H.M.
      • Sejersted O.M.
      Skeletal muscle disorders in heart failure.
      ].
      Several trials have evaluated the possible effects of CrP administration on skeletal muscle performance in patients with muscle hypotonotrophy following surgery and cast immobilisation.
      Both Satolli and Marchesi (1989) [
      • Satolli F.
      • Marchesi G.
      Creatine phosphate in the rehabilitation of patients with muscle hypotonotrophy of the lower extremity.
      ] and Agnese et al. (1992) [
      • Agnese L.
      • Tarello M.
      • Grazioli I.
      Efficacia della creatina fosfato nel trattamento della ipotonotrofia da non uso della muscolatura scheletrica.
      ] showed that patients treated with CrP during physiokinesitherapy for muscle hypotonotrophy recovered muscle strength and power faster and to a greater degree than controls who received physiokinesitherapy alone.
      Lastly, Pirola et al. (1991) reported that CrP administration improves muscle mass recovery even in elderly patients with leg hypotrophy due to femur fracture [
      • Pirola V.
      • Pisani L.
      • Teruzzi P.
      Valutazione del recupero del trofismo muscolare in pazienti anziani con frattura di femore trattati con creatina fosfato e fisiokinesiterapia.
      ]. After the physiokinesitherapy treatment period, patients who received CrP in addition showed a greater net muscle mass recovery (measured by echotomography) than patients who received physiokinesitherapy alone.

      Prospective New Clinical Uses for CrP

      Many articles have been published in recent years on prospective new therapeutic applications of CrP and related compounds in animals and humans.
      Table 3 summarises the emerging CrP clinical applications.
      Table 3Prospective new clinical uses for CrP.
      Clinical uses of CrP with favourable therapeutic effectsReferences
      Kidney hypoxia and renal damage in Henoch-Schonlein purpura
      • Zhang J.
      • Zeng H.
      • Wang N.
      • Tian X.
      • Dou W.
      • Shi P.
      Beneficial effects of creatine phosphate sodium for the treatment of Henoch-Schonlein purpura in patients with early renal damage detected using urinary kidney injury molecule-1 levels.
      Viral myocarditis
      • Yang W.
      • Tang L.
      Clinical Analysis on the Treatment of Pediatric Myocarditis by Neoton.
      ,
      • Niu L.
      • An X.J.
      • Tian J.
      • Wang Y.
      124 cases of clinical analysis of children with viral myocarditis.
      Myocardial injury after neonatal asphyxia
      • Miao P.
      • Sun B.
      • Feng X.
      Treatment of myocardial damage with creatine phosphate following neonatal asphyxia: a meta-analysis.
      Post PCI myocardial injury
      • Ke-Wu D.
      • Xu-Bo S.
      • Ying-Xin Z.
      • Shi-Wei Y.
      • Yu-Jie Z.
      • Dong-Mei S.
      • et al.
      The effect of exogenous creatine phosphate on myocardial injury after percutaneous coronary intervention.
      Cardiocerebral syndrome in acute myocardial infarction
      • Weber P.
      • Vlašicová Y.
      • Lábrová R.
      • Semrád B.
      Asset of creatine phosphate for cardiocerebral syndrome treatment in acute myocardial infarction in old age.
      Acute ischaemic stroke
      • Skrivanek O.
      • Kalvach P.
      • Benetin J.
      • Brzak M.
      • Kukumberg I.
      • Strnad P.
      • et al.
      Creatine phosphate in the treatment of acute ischemic stroke.
      ,
      • Bakala J.
      • Kalita Z.
      SPECT findings in patients with acute stroke treated with NEOTON.
      Moderate to severe hypoxic ischaemic encephalopathy
      • Zhang G.
      • Luo W.
      • Zheng J.
      H. W. Clinical Observation and Blood Gas Changes after the Treatment of Neoton in Neonates with Moderate or Severe Hypoxic Ischaemic Encephalopathy.
      A recent paper demonstrated that CrP administration in patients with Henoch-Schonlein purpura and early renal disease reduces urinary KIM-1 levels (Kidney Injury Molecule 1) and thus corrects kidney hypoxia. Moreover, CrP preconditioning may be able to prevent early renal damage in Henoch-Schonlein purpura nephritis (HSPN) patients [
      • Zhang J.
      • Zeng H.
      • Wang N.
      • Tian X.
      • Dou W.
      • Shi P.
      Beneficial effects of creatine phosphate sodium for the treatment of Henoch-Schonlein purpura in patients with early renal damage detected using urinary kidney injury molecule-1 levels.
      ].
      There are results from studies of CrP therapy in paediatric myocardial damage too [
      • Yang W.
      • Tang L.
      Clinical Analysis on the Treatment of Pediatric Myocarditis by Neoton.
      ]. Niu et al. (2015) observed children with viral myocarditis (VMC) and concluded that “the myocardial protection of creatine phosphate sodium has a definite therapeutic effect on VMC”, with a greater success rate than conventional therapy [
      • Niu L.
      • An X.J.
      • Tian J.
      • Wang Y.
      124 cases of clinical analysis of children with viral myocarditis.
      ].
      Interesting results have been obtained with CrP therapy in the treatment of myocardial injury after neonatal asphyxia. In a meta-analysis involving 400 neonates, Miao et al. (2012) demonstrated that seven days of CrP administration after an asphyxia episode decreased serum CK, CK-MB, LDH, HBDH and cTnI levels [
      • Miao P.
      • Sun B.
      • Feng X.
      Treatment of myocardial damage with creatine phosphate following neonatal asphyxia: a meta-analysis.
      ]. Moreover, CrP therapy shortened the time the infants were hospitalised.
      Creatine phosphate has recently been administered to percutaneous coronary intervention (PCI) patients. By adopting surrogate endpoints, such as creatine kinase MB (CK-MB) and troponin I (TnI) levels, Ke-Wu et al. revealed a marked reduction in the number of patients with post PCI myocardial injury in a CrP-treated group [
      • Ke-Wu D.
      • Xu-Bo S.
      • Ying-Xin Z.
      • Shi-Wei Y.
      • Yu-Jie Z.
      • Dong-Mei S.
      • et al.
      The effect of exogenous creatine phosphate on myocardial injury after percutaneous coronary intervention.
      ].
      Adenosine triphosphate decrease after cerebral anoxia or ischaemia has been shown to be a first step towards cerebral injuries (death or various degrees of disability), and the Cr/CrP system can compensate to some extent for the injuries caused by anoxia or ischaemia. A pioneer study by Weber et al. (1992) analysed the effects of CrP in the treatment of cardiocerebral syndrome (a set of general neuropsychic symptoms) during the first three days of acute myocardial infarction in the elderly [
      • Weber P.
      • Vlašicová Y.
      • Lábrová R.
      • Semrád B.
      Asset of creatine phosphate for cardiocerebral syndrome treatment in acute myocardial infarction in old age.
      ]. Fifty myocardial infarction patients were randomly assigned to CrP treatment (total dose of 18 g by i.v. during three days) or no CrP treatment. Their mental deterioration, measured using the Mini-Mental State Examination, revealed a positive effect of CrP on mental function. The CrP-treated group also showed lower incidences of angina, ventricular arrhythmias and cardiac failure although these differences were not statistically significant.
      Creatine phosphate may also play a role in the treatment of acute ischaemic stroke. Skrivanek et al. (1995) [
      • Skrivanek O.
      • Kalvach P.
      • Benetin J.
      • Brzak M.
      • Kukumberg I.
      • Strnad P.
      • et al.
      Creatine phosphate in the treatment of acute ischemic stroke.
      ], Bakala and Kalita (1995) [
      • Bakala J.
      • Kalita Z.
      SPECT findings in patients with acute stroke treated with NEOTON.
      ] and Zhang et al. (2004) [
      • Zhang G.
      • Luo W.
      • Zheng J.
      H. W. Clinical Observation and Blood Gas Changes after the Treatment of Neoton in Neonates with Moderate or Severe Hypoxic Ischaemic Encephalopathy.
      ] have published clinical experiences with CrP in acute cerebral ischaemia.
      Skrivanek et al. (1995) treated 119 patients with cerebral ischaemia within eight hours of symptom onset; 64 received CrP in addition to standard cerebrovascular medication (total dose of 34 g by i.v. during three days) [
      • Skrivanek O.
      • Kalvach P.
      • Benetin J.
      • Brzak M.
      • Kukumberg I.
      • Strnad P.
      • et al.
      Creatine phosphate in the treatment of acute ischemic stroke.
      ]. Death occurred in 4/64 CrP-treated patients and 9/55 controls. Comparison of clinical improvement using the Stroke Assessment System (SAS) and the Toronto Stroke Scale (TSS) revealed a better score trend in the CrP group, in particular in the patients for whom treatment started within three hours.
      The possibility that CrP may improve ischaemic stroke treatment was also suggested in an open study by Bakala and Kalita (1995). Using the single-photon-emission computed tomography method (technetium-99m), these investigators observed improvement in cerebral blood flow and a better clinical evolution in patients treated with CrP (32 g in five days) [
      • Bakala J.
      • Kalita Z.
      SPECT findings in patients with acute stroke treated with NEOTON.
      ].
      Lastly, Zhang et al. (2004) observed the effects of adding CrP to conventional therapy in 60 neonates with moderate to severe hypoxic ischaemic encephalopathy at birth (1 g daily for 5–7 days) [
      • Zhang G.
      • Luo W.
      • Zheng J.
      H. W. Clinical Observation and Blood Gas Changes after the Treatment of Neoton in Neonates with Moderate or Severe Hypoxic Ischaemic Encephalopathy.
      ]. Compared to the conventional treatment aimed at maintaining good ventilation, blood flow to organs, blood glucose at the upper limit of the norm, control of convulsion, depressurisation of intracranial pressure, etc., the 30 neonates who also received CrP, showed a significant improvement in all the efficacy indices considered, including the evaluation of various times, such as the time of convulsion disappearance, consciousness recovery, primitive reflex recovery and brain stem disorder disappearance.

      Conclusion

      Energy distribution in the intracellular environment pivots on CrP. Clinical and preclinical studies have demonstrated that a CrP decrease in cardiac and skeletal muscle cells determines a fall in ATP and consequent cell energy impairment.
      Strumia et al. (2012) stated that the “physiological role of CrP in the regulation of heart functions has been recently re-evaluated and revised.” [
      • Strumia E.
      • Pelliccia F.
      • D’Ambrosio G.
      Creatine phosphate: pharmacological and clinical perspectives.
      ] Very recently, Landoni et al. (2016) conducted a meta-analysis of 22 randomised trials (3400 patients) comparing CrP administration with placebo or standard treatment in patients with coronary artery disease, chronic heart failure or undergoing heart surgery [
      • Landoni G.
      • Zangrillo A.
      • Lomivorotov V.V.
      • Likhvantsev V.
      • Ma J.
      • De Simone F.
      • et al.
      Cardiac protection with phosphocreatine: a meta-analysis.
      ]. According to their analysis, CrP administration reduced all-cause short-term mortality in this population of patients. Patients receiving CrP had lower all-cause mortality when compared with controls [61/1731 (3.5%) vs. 177/1667 (10.6%); p = 0.04]. Moreover, CrP administration was associated with an improvement in cardiac results, including inotrope use, ejection fraction, CK-MB release and the incidence of major arrhythmias. It also improved spontaneous recovery of heart performance in the subgroup of cardiopulmonary bypass patients.
      New CrP uses have been investigated for adults, children and the elderly. Promising results have been obtained in the neurological field, for example in cerebral ischaemia and hypoxic ischaemic encephalopathy. Moreover, CrP has been shown to protect against myocardium damage in viral myocarditis in children, and to prevent myocardial damage after percutaneous coronary intervention.
      The prevention and treatment of myocardial damage are currently CrP administration objectives in medical cardiology and heart surgery. The positive effects of adding CrP to standard treatments for acute myocardial infarction, heart failure, dilated cardiomyopathy and other medical conditions include a decrease in heart enzyme leakage (CPK, MB-CPK, LDH), an improvement in ECG signs of ischaemia-necrosis and haemodynamic conditions (e.g. ejection fractions, stroke volume, cardiac output), and a decrease in arrhythmic complications and left-ventricular dilation.
      Creatine phosphate use is also well established in heart surgery: the intraoperative and perioperative administration of CrP improves the spontaneous recovery of sinus rhythm after declamping, reduces direct-current shocks and total pulses for defibrillation, decreases the use and doses of inotropic drugs, and reduces arrhythmic complications, the incidence of A-V blocks and the appearance and leakage of cardiac injury enzymatic markers (CPK, MB-CPK and troponins).
      New randomised controlled trials are always welcome, especially for potential new therapeutic uses of CrP. Considering that research on the energetic metabolism in humans is rapidly growing, and increasingly involves new mixed techniques of lab plus molecular imaging [
      • Weiduschat N.
      • Mao N.X.
      • Beal M.F.
      • Nirenberg M.J.
      • Shungu D.C.
      • Henchcliffe C.
      Usefulness of proton and phosphorus MR spectroscopic imaging for early diagnosis of Parkinson’s disease.
      ,
      • Wang J.M.
      • Chu Y.
      • Li W.
      • Wang X.Y.
      • Guo J.H.
      • Yan L.L.
      • et al.
      Simultaneous determination of creatine phosphate, creatine and 12 nucleotides in rat heart by LC-MS/MS.
      ,
      • Sengupta A.
      • Grover M.
      • Chakraborty A.
      • Saxena S.
      HEPNet: A Knowledge Base Model of Human Energy Pool Network for Predicting the Energy Availability Status of an Individual.
      ], the results likely to arise from future trials could define the therapeutic role of CrP even better.

      Conflicts of Interest Disclosures

      Gaddi Antonio V. reports being an external consultant of Alfa Wassermann.
      Galuppo Paolo reports being an officer and employee of Alfa Wassermann.
      Yang Jiefu declares that he has no conflict of interest which may arise from being named as author on this manuscript.

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