Genotype-driven pharmacokinetic simulations of warfarin levels in Puerto Ricans.

Objectives The inter-individual variability of warfarin dosing has been linked to genetic polymorphisms. This study was aimed at performing genotype-driven pharmacokinetic (PK) simulations to predict warfarin levels in Puerto Ricans. Methods Analysis of each individual dataset was performed by one-compartmental modeling using WinNonlin®v6.4. The k e of warfarin given a cytochrome P450 2C9 (CYP2C9) genotype ranged from 0.0189 to 0.0075 h-1. K a and V d parameters were taken from literature. Data from 128 subjects were divided into two groups (i.e., wild-types and carriers) and statistical analyses of PK parameters were performed by unpaired t-tests. Results In the carrier group (n=64), 53 subjects were single-carriers and 11 double-carriers (i.e., *2/*2, *2/*3, *2/*5, *3/*5, and *3/*8). The mean peak concentration (Cmax) was higher for wild-type (0.36±0.12 vs. 0.32±0.14 mg/L). Likewise, the average clearance (CL) parameter was faster among non-carriers (0.22±0.03 vs. 0.17±0.05 L/h; p=0.0001), with also lower area under the curve (AUC) when compared to carriers (20.43±6.97 vs. 24.78±11.26 h mg/L; p=0.025). Statistical analysis revealed a significant difference between groups with regard to AUC and CL, but not for Cmax. This can be explained by the variation of k e across different genotypes. Conclusions The results provided useful information for warfarin dosing predictions that take into consideration important individual PK and genotyping data.

Genotype-driven pharmacokinetic simulations of warfarin levels in Puerto Ricans.

OBJECTIVES: The inter-individual variability of warfarin dosing has been linked to genetic polymorphisms. This study was aimed at performing genotype-driven pharmacokinetic (PK) simulations to predict warfarin levels in Puerto Ricans. METHODS: Analysis of each individual dataset was performed by one-compartmental modeling using WinNonlin®v6.4. The ke of warfarin given a cytochrome P450 2C9 (CYP2C9) genotype ranged from 0.0189 to 0.0075 h-1. Ka and Vd parameters were taken from literature. Data from 128 subjects were divided into two groups (i.e., wild-types and carriers) and statistical analyses of PK parameters were performed by unpaired t-tests. RESULTS: In the carrier group (n=64), 53 subjects were single-carriers and 11 double-carriers (i.e., *2/*2, *2/*3, *2/*5, *3/*5, and *3/*8). The mean peak concentration (Cmax) was higher for wild-type (0.36±0.12 vs. 0.32±0.14 mg/L). Likewise, the average clearance (CL) parameter was faster among non-carriers (0.22±0.03 vs. 0.17±0.05 L/h; p=0.0001), with also lower area under the curve (AUC) when compared to carriers (20.43±6.97 vs. 24.78±11.26 h mg/L; p=0.025). Statistical analysis revealed a significant difference between groups with regard to AUC and CL, but not for Cmax. This can be explained by the variation of ke across different genotypes. CONCLUSIONS: The results provided useful information for warfarin dosing predictions that take into consideration important individual PK and genotyping data.

A comparative pharmacokinetic and pharmacodynamic study of two novel Cuban PEGylated rHuEPO versus MIRCERA® and ior®EPOCIM.

CONTEXT: The recombinant human erythropoietin (rHuEPO) stimulates the erythropoiesis process. Because this glycoprotein has a short half-life, it needs to be administrated two to three times a week. One of the technics to solve this issue is the PEGgilation. AIMS: To evaluate the pharmacokinetics (PK) and pharmacodynamics of two new branched PEGylated erythropoietins (i.e., an asymmetric 32 kDa-PEG2-rHuEPO and a symmetric 40 kDa-PEG2-rHuEPO molecule) compared to non-PEGylated ior®EPOCIM and MIRCERA®. METHODS: Serum concentrations of both PEGylated and non-PEGylated erythropoietins were measured at various time points in order to determine PK parameters using non-compartmental analysis approach. The reticulocyte (%), erythrocyte count and hemoglobin levels were ascertained in order to compare the effect of these molecules after administrating a single intravenous dose (10 µg/kg) of each product in male New Zealand rabbits. RESULTS: Both branched PEGylated erythropoietin forms exhibited half-lives that were significantly longer than ior®EPOCIM (p<0.05), but not statistically different to MIRCERA®. The mean elimination half-life increased from 4 h (ior®EPOCIM) to 131 h for the 32 kDa-PEG2-rHuEPO and 119 h for the 40 kDa-PEG2-rHuEPO. Conversely, MIRCERA® exhibits a half-life of 64 h. Both PEGylated erythropoietin products significantly enhanced the stimulating effect on reticulocytes and erythrocytes formation, as well as on hemoglobin levels, when compared to ior®EPOCIM treatment up to 42 days post-dose. CONCLUSIONS: The PEGylation strategy employed in this study is an effective method to modify the pharmacokinetics and pharmacodynamics of rHuEPO molecule achieving higher half-lives and, therefore, longer in vivo bioactivity. Both of the branched PEGylated-EPO forms tested are promising candidates for human testing.

CONTEXTO: La eritropoyetina humana recombinante (rHuEPO) estimula la formación de eritrocitos en la medula ósea. Esta glicoproteína terapéutica presenta rápida eliminación en el organismo. Una de las estrategias tecnológicas para resolver esta problemática es la PEGgilación. OBJETIVOS: Evaluar la farmacocinética y la farmacodinámica de dos nuevas eritropoyetinas PEGiladas ramificadas (una asimétrica de 32 kDa-PEG2-rHuEPO y otra simétrica de 40 kDa-PEG2-rHuEPO) en comparación con ior®EPOCIM y el producto de referencia MIRCERA®. MÉTODOS: Se midieron las concentraciones séricas de eritropoyetina PEGilada y no PEGilada, a diferentes tiempos, para determinar los parámetros farmacocinéticos usando el método de análisis no compartimental. Se determinaron los % de reticulocitos, los niveles de eritrocitos y hemoglobina para comparar el efecto de estas moléculas después de administrar a dosis única 10 µg/kg por vía intravenosa en conejos Nueva Zelanda machos. RESULTADOS: Las eritropoyetinas PEGiladas ramificadas presentaron semividas significativamente superiores a ior®EPOCIM (p<0.05), pero no fueron estadísticamente diferentes a MIRCERA®. El t1/2 aumentó de 4 h (ior®EPOCIM) a 131 h para la 32 kDa-PEG2-rHuEPO y 119 h para la 40 kDa-PEG2-rHuEPO, respectivamente. Ambas eritropoyetinas PEGiladas mejoraron significativamente el efecto estimulante sobre la formación de reticulocitos y eritrocitos, así como los niveles de hemoglobina, en comparación con ior®EPOCIM hasta 42 días después de la dosis. CONCLUSIONES: La estrategia de PEGilación, empleada en este estudio, es un método efectivo para modificar la farmacocinética y farmacodinamia de moléculas de eritropoyetinas. Esta tecnología permitió aumentar la semivida de estas moléculas, así como prolongar su bioactividad in vivo. Ambas formas ramificadas de rHuEPO PEGiladas son candidatos prometedores para su uso clínico.