Population Pharmacokinetics of Phosphocreatine and Its Metabolite Creatine in Children With Myocarditis

Creatine homeostasis and the kidney: comparison between kidney transplant recipients and healthy controls

Creatine is a natural nitrogenous organic acid that is integral to energy metabolism and crucial for proper cell functioning. The kidneys are involved in the first step of creatine production. With kidney transplantation being the gold-standard treatment for end-stage kidney disease, kidney transplant recipients (KTR) may be at risk of impaired creatine synthesis. We aimed to compare creatine homeostasis between KTR and controls. Plasma and urine concentrations of arginine, glycine, guanidinoacetate, creatine and creatinine were measured in 553 KTR and 168 healthy controls. Creatine intake was assessed using food frequency questionnaires. Iothalamate-measured GFR data were available in subsets of 157 KTR and 167 controls. KTR and controls had comparable body weight, height and creatine intake (all P > 0.05). However, the total creatine pool was 14% lower in KTR as compared to controls (651 ± 178 vs. 753 ± 239 mmol, P < 0.001). The endogenous creatine synthesis rate was 22% lower in KTR as compared to controls (7.8 ± 3.0 vs. 10.0 ± 4.1 mmol per day, P < 0.001). Despite lower GFR, the plasma guanidinoacetate and creatine concentrations were 21% and 41% lower in KTR as compared to controls (both P < 0.001). Urinary excretion of guanidinoacetate and creatine were 66% and 59% lower in KTR as compared to controls (both P < 0.001). In KTR, but not in controls, a higher measured GFR was associated with a higher endogenous creatine synthesis rate (std. beta: 0.21, 95% CI: 0.08; 0.33; P = 0.002), as well as a higher total creatine pool (std. beta: 0.22, 95% CI: 0.11; 0.33; P < 0.001). These associations were fully mediated (93% and 95%; P < 0.001) by urinary guanidinoacetate excretion which is consistent with production of the creatine precursor guanidinoacetate as rate-limiting factor. Our findings highlight that KTR have a disturbed creatine homeostasis as compared to controls. Given the direct relationship of measured GFR with endogenous creatine synthesis rate and the total creatine pool, creatine supplementation might be beneficial in KTR with low kidney function.Trial registration ID: NCT02811835.Trial registration URL: https://clinicaltrials.gov/ct2/show/NCT02811835 .

Clinical Effect Analysis of Different Doses of Creatine Phosphate Sodium Combined with Immunoglobulin in the Treatment of Pediatric Viral Myocarditis

The purpose of this paper was to unravel the clinical effect analysis of different doses of creatine phosphate sodium (CPS) combined with immunoglobulin in the treatment of pediatric viral myocarditis (VMC). One hundred and twenty children with VMC were recruited and randomized into three groups (40 patients each). Group I received 1.0 g of CPS dissolved in 100 mL of 5% glucose injection intravenously 1 time/day; group II received 1.25 g of CPS dissolved in 125 mL of 5% glucose injection intravenously 1 time/day; group III received 1.5 g of CPS dissolved in 150 mL of 5% glucose injection intravenously 1 time/day; then all three groups were treated with combined use of immunoglobulin (300-400 mg/day) intravenously once a day; and all three groups were treated for 14 days. The clinical efficacy, cardiac function, serum inflammatory factor levels, immune function, and the occurrence of drug toxicity and adverse effects of the children in the three groups were compared after 14 days of treatment. All three groups achieved better therapeutic effects after treatment, in which the effective rate of the Group II and Group III was notably higher versus the Group I. Lower levels of cTnI, CK-MB, LDH, AST, IL-18, IL-6, IFN-γ, and LVEDD and higher CD3+, CD4+, and CD4+/CD8+, FS, and LVEF values were noted in the Group II and Group III versus the Group I, and the results were more pronounced in the high-dose group. The liver and kidney functions of the children in the three groups before and after treatment did not show any significant changes and the incidence of adverse reactions during the treatment period was low in all three groups. Children with VMC can be treated with high-dose CPS in combination with immunoglobulin, which can improve their cardiac function and immune function and reduce the inflammatory response with good overall therapeutic efficacy and fewer adverse effects.

Therapeutic effect of captopril combined with phosphocreatine sodium on viral myocarditis

OBJECTIVE

To analyze the therapeutic effect of captopril combined with phosphocreatine sodium in patients with viral myocarditis.

METHODS

A total of 140 patients with infectious myocarditis who received treatment in Hanzhong City People's Hospital from December 2019 to January 2022 were retrospectively enrolled as study subjects. 61 of them were treated with captopril and constituted the control group (CG), and the remaining 79 who received phosphocreatine sodium in addition to captopril were the research group (RG). Variables were observed and compared between the two groups, including clinical efficacy, adverse reactions during treatment, and changes in myocardial enzymes, cardiac function, troponin, and inflammatory factors. According to therapeutic effect, those patients with marked results were categorized as the significant improvement group, and those whose results were just effective or ineffective were the insignificant improvement group. The risk factors affecting the efficacy of the patients were analyzed by logistic regression.

RESULTS

Compared to the CG, the RG had greater decreases in aspartate aminotransferase (AST), creatine kinase isoenzyme (CK-MB), creatine kinase (CK), and lactate dehydrogenase (LDH) (all P < 0.05). The left ventricular ejection fraction (LVEF), left ventricular fractional shortening (FS), and left ventricular stroke volume (SV) in the RG increased significantly more after treatment (P < 0.05), while the levels of high-sensitivity troponin I (cTnI) and cardiac troponin T (cTnT) decreased more significantly (P < 0.05) compared to the CG. The levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the RG were more down-regulated (P < 0.05), and they had a higher overall response rate after treatment (P < 0.05). However, there was no significant difference in the incidence of adverse reactions between these two groups (P > 0.05). Multivariate logistic regression analysis showed that CK-MB, LVEF, cTnI, and cTnT were independent factors affecting the efficacy.

CONCLUSION

Captopril combined with phosphocreatine sodium can reduce the inflammatory response in patients with infectious myocarditis, improve cardiac function, and improve the therapeutic efficacy.

Population Pharmacokinetics of Phosphocreatine and Its Metabolite Creatine in Children With Myocarditis

Objective: This study aimed to develop a parent-metabolite joint population pharmacokinetic model to characterize the pharmacokinetic (PK) profile for phosphocreatine (PCr) and its metabolite creatine (Cr) in children with myocarditis and to use this model to study the PK profile of different dosing schemes. Methods: One hundred pediatric patients with myocarditis were enrolled. Blood samples were collected at baseline and approximately 30, 40 or 50, 75, and 180 min after a single dose of phosphocreatine sodium. Plasma PCr and Cr concentrations were determined using an HPLC-MS/MS method. A nonlinear mixed effect model approach was used to build the population pharmacokinetic model. After validation, the model was used for simulations to evaluate the PK profile of different dosing schemes. Results: A total of 997 plasma concentrations (498 for PCr and 499 for Cr) were included in the analysis. A four-compartment chain model (central and peripheral compartments for both PCr and Cr) with the first-order elimination adequately characterized the in vivo process of PCr and Cr. Allometric scaling based on bodyweight was applied to the PK parameters. The covariate analysis identified that the glomerular filtration rate (GFR) was strongly associated with Cr clearance. Bootstrapping and visual predictive checks suggested that a robust and reliable pharmacokinetic model was developed. The simulation results showed that PCr had no accumulation in vivo. With the infusion of PCr, the concentration of Cr increased rapidly. Conclusion: A joint population pharmacokinetic model for PCr and Cr in pediatric patients with myocarditis was successfully developed for the first time.