Plasma Concentrations Of Pravastatin Research Articles

Pharmacokinetic and Pharmacodynamic Interactions Between Concomitantly used Gliclazide with Pravastatin

Diabetic hyperlipidemia is associated with increased lipoproteins in the blood hence, the introduction of a lipid lowering drugs aids in controlling the same. This comedication may lead to drug–drug interactions between anti-diabetic and anti-hyperlipidemic drugs. The current research is aimed at evaluating the pharmacodynamic and pharmacokinetic interactions of gliclazide (anti-diabetic) therapy by pravastatin (anti-hyperlipidemic) when administrated in combination. The studies conducted on rats dosed with gliclazide, pravastatin individually and in combination. Statistical comparisons of plasma concentration – response study in groups with gliclazide alone, pravastatin alone and in combination was carried out. The response study among concentrations and time were calculated employing student’s paired T-Test. The results indicate that gliclazide is completely absorbed with peak plasma concentration of 6.82±0.12 ng/ml and 7.82±0.12 ng/ml when administrated alone and 7.22±0.12 ng/ml and 7.22±0.12 ng/ml when administrated in combination in diabetic rats on first day (day 1) and eighth day (day8) respectively. Similarly peak plasma concentration of pravastatin are 3.92±0.03 ng/ml and 4.80±0.04 ng/ml when administrated alone and 3.683±0.02 ng/ml and 4.657±0.04 ng/ml when administrated in combination in diabetic rats on first day (day 1) and eighth day (day 8) respectively.There was no statistically noteworthy variation observed in peak plasma concentration (P>0.05). Similarly no variations observed in values of tmax, AUC and T1/2. The fasting serum glucose concentrations in normal and STZ-induced diabetic group on first day (day 1) and eighth day (day 8) were analyzed. The reduction of blood glucose levels at different time intervals on administration of gliclazide and pravastatin alone and in combination analyzed and results indicate no significant change in pharmacodynamic parameters.
 Hence the results conclude that combinational therapy of gliclazide and pravastatin were found safe and highly potential in treating hyperlipidemia patients.

Characterization of Long-Lasting Oatp Inhibition by Typical Inhibitor Cyclosporine A and In Vitro–In Vivo Discrepancy in Its Drug Interaction Potential in Rats

Quantitative assessment of potential drug-drug interactions (DDIs) is one of the major focuses in drug development. The aim of the present study was to quantitatively evaluate in vitro–in vivo discrepancy of DDI potential for prototypical organic anion transporting polypeptide (Oatp) inhibitor cyclosporine A (CsA) using rats. Plasma concentration of pravastatin, prototypical Oatp substrate, after oral administration was increased by CsA intravenously administered at 1 d before the pravastatin administration. The ratio of the area under the curve of pravastatin to the control was much higher than the R-values calculated using the plasma unbound concentrations of CsA and the inhibition constant (Ki) assessed in isolated hepatocytes, indicating in vitro–in vivo discrepancy. This interaction with pravastatin persisted for 3 d after CsA administration, demonstrating long-lasting inhibition in vivo. The Ki value for unbound CsA in the presence of serum was comparable with that in its absence. M1, the major metabolite of CsA inhibited pravastatin uptake at much higher concentration compared with its plasma unbound concentration. Thus, the DDI potential of CsA-mediated hepatic Oatp inhibition cannot be extrapolated from in vitro data, and this could be due to the long-lasting Oatp inhibition by CsA, but not the effect of plasma protein or metabolites.

Safety and pharmacokinetics of pravastatin used for the prevention of preeclampsia in high-risk pregnant women: a pilot randomized controlled trial

Preeclampsia complicates approximately 3-5% of pregnancies and remains a major cause of maternal and neonatal morbidity and mortality. It shares pathogenic similarities with adult cardiovascular disease as well as many risk factors. Pravastatin, a hydrophilic, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitor, has been shown in preclinical studies to reverse various pathophysiological pathways associated with preeclampsia, providing biological plausibility for its use for preeclampsia prevention. However, human trials are lacking. As an initial step in evaluating the utility of pravastatin in preventing preeclampsia and after consultation with the US Food and Drug Administration, we undertook a pilot randomized controlled trial with the objective to determine pravastatin safety and pharmacokinetic parameters when used in pregnant women at high risk of preeclampsia. We conducted a pilot, multicenter, double-blind, placebo-controlled, randomized trial of women with singleton, nonanomalous pregnancies at high risk for preeclampsia. Women between 12(0/7) and 16(6/7) weeks' gestation were assigned to daily pravastatin 10 mg or placebo orally until delivery. Primary outcomes were maternal-fetal safety and pharmacokinetic parameters of pravastatin during pregnancy. Secondary outcomes included rates of preeclampsia and preterm delivery, gestational age at delivery, birthweight, and maternal and cord blood lipid profile (clinicaltrials.gov identifier NCT01717586). Ten women assigned to pravastatin and 10 to placebo completed the trial. There were no differences between the 2 groups in rates of study drug side effects, congenital anomalies, or other adverse or serious adverse events. There was no maternal, fetal, or neonatal death. Pravastatin renal clearance was significantly higher in pregnancy compared with postpartum. Four subjects in the placebo group developed preeclampsia compared with none in the pravastatin group. Although pravastatin reduced maternal cholesterol concentrations, umbilical cord cholesterol concentrations and infant birthweight were not different between the groups. The majority of umbilical cord and maternal pravastatin plasma concentrations at the time of delivery were below the lower limit of quantification of the assay. Pravastatin use was associated with a more favorable pregnancy angiogenic profile. This study provides preliminary safety and pharmacokinetic data regarding the use of pravastatin for preventing preeclampsia in high-risk pregnant women. Although the data are preliminary, no identifiable safety risks were associated with pravastatin use in this cohort. This favorable risk-benefit analysis justifies using pravastatin in a larger clinical trial with dose escalation.

Synergistic interaction between genetics and disease on pravastatin disposition

A genome wide association study and multiple pharmacogenetic studies have implicated the hepatic uptake transporter organic anion transporting polypeptide-1B1 (OATP1B1) in the pharmacokinetics and musculoskeletal toxicity of statin drugs. Other OATP uptake transporters can participate in the transport of pravastatin, partially compensating for the loss of OATP1B1 in patients carrying the polymorphism. Non-alcoholic steatohepatitis (NASH) in humans and in a diet-induced rodent model alter the expression of multiple OATP transporters. To determine how genetic alteration in one Oatp transporter can interact with NASH-associated changes in Oatp expression we measured the disposition of intravenously administered pravastatin in Slco1b2 knockout (Slco1b2(-/-)) and wild-type (WT) mice fed either a control or a methionine and choline deficient (MCD) diet to induce NASH. Genetic loss of Oatp1b2, the rodent ortholog of human OATP1B transporters, caused a modest increase in pravastatin plasma concentrations in mice with healthy livers. Although a diet-induced model of NASH decreased the expression of multiple hepatic Oatp transporters, it did not alter the disposition of pravastatin compared to WT control mice. In contrast, the combination of NASH-associated decrease in compensatory Oatp transporters and Oatp1b2 genetic loss caused a synergistic increase in plasma area under the curve (AUC) and tissue concentrations in kidney and muscle. Our data show that NASH alters the expression of multiple hepatic uptake transporters which, due to overlapping substrate specificity among the OATP transporters, may combine with the pharmacogenetic loss of OATP1B1 to increase the risk of statin-induced adverse drug reactions.

Effect of oxidative stress on expression and function of human and rat organic anion transporting polypeptides in the liver

Reactive oxygen species (ROS) have physiological function and involve alteration of physical state. However, it is not clear effect of oxidative stress on pharmacokinetics. Organic anion transporting polypeptides (human: OATPs, rodent: Oatps) are important for uptake of endogenous and exogenous compounds into hepatocytes. Thus, alteration of OATPs/Oatps expression level may affect pharmacokinetics of various drugs. In this study, we investigated the alteration of OATPs/Oatps expression levels and function by oxidative stress, and the effect of alteration of those on pharmacokinetics of a typical OATPs/Oatps substrate pravastatin. OATPs/Oatps expression levels and function were altered by H2O2-induced oxidative stress in in vitro experiments. The alteration of Oatps expression by oxidative stress also occurred in in vivo experiments. Oatp1a1, Oatp1a4 and Oatp1b2 expression in the liver were decreased in rats fed powdery diet containing 2% inosine, which induces oxidative stress through activation of xanthine oxidase, for 1 day. The decrease in Oatps expression levels by oxidative stress caused the suppression of pravastatin uptake to the liver, and resulted in high plasma concentration of pravastatin and low biliary excretion. In conclusion, oxidative stress induces alteration of OATPs/Oatps expression and function in hepatocytes, resulting in alteration of pharmacokinetics of their substrates.

Differential Effect of Grapefruit Juice on Intestinal Absorption of Statins Due to Inhibition of Organic Anion Transporting Polypeptide and/or P-glycoprotein

The purpose of this study is to examine the contributions of organic anion transporting polypeptide (Oatp) and/or P-glycoprotein (P-gp) to grapefruit juice (GFJ) interaction with two statins, pravastatin and pitavastatin, which undergo negligible metabolism in rats. The two statins were found to be substrates of both Oatp1a5 and Oatp2b1, whereas pitavastatin, but not pravastatin, was a substrate of P-gp. The plasma concentration of pravastatin after oral administration was significantly decreased by GFJ and naringin, whereas that of pitavastatin was significantly increased. Naringin inhibited Oatp1a5- and Oatp2b1-mediated uptake of pravastatin and Oatp1a5-mediated, but not Oatp2b1-mediated, uptake of pitavastatin. Naringin also inhibited P-gp-mediated transport of pitavastatin. These results suggested that the decrease of pravastatin absorption in the presence of GFJ is due to the inhibitory effect of naringin on Oatp, whereas the increase of pitavastatin is due to the inhibition of P-gp. These observations are consistent with the results of in situ absorption studies. In conclusion, Oatp and/or P-gp contribute to the intestinal absorption of statins, and the differential effect of GFJ on pravastatin and pitavastatin absorption is at least partly accounted for by the different inhibitory effects of naringin on these transporters. © 2011 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:3843–3853, 2011

Application of physiologically based pharmacokinetic modeling and clearance concept to drugs showing transporter-mediated distribution and clearance in humans

This review illustrates the concept of a rate-determining process in the overall hepatic elimination of anionic drugs that involves transporters in the uptake process. A kinetic study in rats has demonstrated that uptake is the rate-determining process for most anionic drugs, and this is likely to hold true for the hepatic elimination of statins in humans. To simulate the effects of variations in the transporter activities on systemic and liver exposure, a physiologically based pharmacokinetic model was constructed for pravastatin, the overall elimination of which involves OATP1B1 and MRP2 in the hepatic uptake and canalicular efflux, respectively. The plasma concentrations of pravastatin in humans were successfully reproduced using the kinetic parameters extrapolated from in vitro data obtained using human hepatocytes and canalicular membrane vesicles and the scaling factors determined in rats. Sensitivity analyses showed that a variation in hepatic uptake altered the plasma concentration of pravastatin markedly, but had a small effect on the liver concentration, and vice versa for the canalicular efflux. Therefore, variation in the OATP1B1 activities will have small and large impacts on the therapeutic efficacy and adverse effect (myopathy) of pravastatin, respectively, whereas that affecting the MRP2 activities may have an opposite effect (i.e., large and small impacts on the therapeutic efficacy and side effect). This pharmacokinetic characteristics likely hold true for other anionic statins, i.e., variation of OATP1B1 is associated with the risk of adverse reactions, whereas that of sequestration mechanisms causes the variation of their pharmacological effect.

Effects of a concomitant single oral dose of rifampicin on the pharmacokinetics of pravastatin in a two-phase, randomized, single-blind, placebo-controlled, crossover study in healthy Chinese male subjects

Background: Pravastatin is a potent cholesterol-lowering agent; ~34% of an oral dose of pravastatin is eliminated unchanged through biliary and urinary excretion. Rifampicin is an inducer of drug metabolism enzymes, and it affects the activities of transporters involved in pravastatin disposition. Drug-drug interaction between rifampicin and pravastatin is possible because of the effects of rifampicin on the activities of drug transporters. Objective: This study was designed to investigate the effects of a single oral dose of rifampicin on the pharmacokinetics of pravastatin. Methods: Healthy Chinese male volunteers were recruited for this 2-phase, single-blind, placebo-controlled, crossover study. The subjects were randomly divided into 2 groups to receive either rifam-picin or placebo concomitantly with pravastatin. All subjects received a 20-mg oral dose of pravastatin on days 1 and 9, separated by an 8-day washout period. Subjects in the rifampicin group received a single 600-mg oral dose of rifampicin on day 1 and placebo on day 9; those in the placebo group received placebo on day 1 and a single 600-mg oral dose of rifampicin on day 9. High-performance liquid chromatography-tandem mass spectrometry was used to determine plasma concentrations of pravastatin for up to 12 hours after administration. Results: Twelve volunteers participated in the study (6 per group). The mean (SD) age of the subjects was 20 (2) years (range, 18–25 years). The mean height of the subjects was 174 (4) cm (range, 168–180 cm), and the mean weight was 69.2 (3.7) kg (range, 65–77 kg). The mean pharmacokinetic parameters for pravastatin that changed significantly were as follows (rifampicin and placebo groups, respectively): C max (315.7 [227.2] and 115.8 [77.5] ng · mL −1 [ P = 0.009]); AUC 0–12 (604.8 [73.3] and 259.0 [133.4] ng · h · mL −1 [ P < 0.001]); AUC 0–∞) (623.3 [248.8] and 275.1 [58.5] ng · h · mL −1 [ P < 0.001]); and apparent oral clearance (CL/F) (0.52 [0.18] and 1.30 [0.58] L · h −1 · kg −1 [ P < 0.001]). No significant changes in the T max or t ½ of pravastatin were observed. All subjects tolerated pravastatin well during both phases of the study, with or without coadministration of rifampicin. None of the subjects withdrew from the study. Conclusion: Coadministration of a single oral dose of rifampicin significantly increased the plasma concentration of pravastatin in this group of healthy Chinese male subjects.

Effect of the Brand and Generic Medicine of Pravastatin on Dyslipidemia in Rabbits Fed a High Cholesterol Diet

Mevalotin containing pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, is the brand medicine and well known to be effective for patients with dyslipidemia. Now, more than 20 generic pravastatins are available for clinical therapy. We compared pharmaceutical property of Mevan,a generic pravastatin, with that of Mevalotin.According to the definition of the Japanese Pharmacopoeia, Mevalotin 10 mg tablets were uniform in pravastatin content, whereas 5 mg tablets were rather variable. Variation in pravastatin content of Mevan 5 mg tablets was the same as Mevalotin 5 mg, whereas that of 10 mg tablets was very variable. The plasma concentration of pravastatin in the normal rabbits continuously increased until 180 min after oral administration of 30 mg Mevan, whereas it increased in a biphasic pattern after 30 mg Mevalotin.All rabbits were fed 0.2% cholesterol diet throughout the experiment. After 8 weeks, oral administration of either Mevalotin or Mevan was started at the dose of 30 mg pravastatin/day for 16 weeks. After a transient increase for a few weeks, the plasma levels of total- and LDL-cholesterol gradually decreased in Mevalotingroup, whereas these levels did not significantly changed in Mevan group within 16 weeks. The level of HDL-cholesterol in Mevan group tended to increase but not in Mevalotin group. The triglyceride level in Mevan group changed as well as that in Mevalotin group until 10 weeks after administration, and then gradually increased. The present results suggest that pharmaceutical properties of Mevan are not always identical with those of Mevalotin.

Physiologically Based Pharmacokinetic Modeling to Predict Transporter-Mediated Clearance and Distribution of Pravastatin in Humans

Hepatobiliary excretion mediated by transporters, organic anion-transporting polypeptide (OATP) 1B1 and multidrug resistance-associated protein (MRP) 2, is the major elimination pathway of an HMG-CoA reductase inhibitor, pravastatin. The present study examined the effects of changes in the transporter activities on the systemic and liver exposure of pravastatin using a physiologically based pharmacokinetic model. Scaling factors, determined by comparing in vivo and in vitro parameters of pravastatin in rats for the hepatic uptake and canalicular efflux, were obtained. The simulated plasma and liver concentrations and biliary excretion profiles were very close to the observed data in rats under linear and nonlinear conditions. In vitro parameters, determined in human cryopreserved hepatocytes and canalicular membrane vesicles, were extrapolated to in vivo parameters using the scaling factors obtained in rats. The simulated plasma concentrations of pravastatin were close to the reported values in humans. Sensitivity analyses showed that changes in the hepatic uptake ability altered the plasma concentration of pravastatin markedly but had a minimal effect on the liver concentration, whereas changes in the ability of canalicular efflux altered the liver concentration of pravastatin markedly but had a small effect on the plasma concentration. In conclusion, the model allows the prediction of the disposition of pravastatin in humans. The present study suggests that changes in the OATP1B1 activities may have a small and a large impact on the therapeutic efficacy and side effect (myopathy) of pravastatin, respectively, whereas those in the MRP2 activities may have opposite impacts (i.e., large and small impacts on the therapeutic efficacy and side effect).

Pharmacokinetic Comparison of the Potential Over-the-Counter Statins Simvastatin, Lovastatin, Fluvastatin and Pravastatin

HMG-CoA reductase inhibitors (statins) dose-dependently lower both the level of low-density lipoprotein cholesterol and risk of cardiovascular disease. In 2004, the UK approved a low-dose over-the-counter (OTC) simvastatin, but the US has rejected applications for non-prescription preparations of statins. The pharmacokinetics and interaction potentials of the possible OTC candidate statins simvastatin, lovastatin, fluvastatin and pravastatin are clearly different. Simvastatin and lovastatin are mainly metabolized by cytochrome P450 (CYP) 3A, fluvastatin is metabolized by CYP2C9, and pravastatin is excreted largely unchanged. Several cell membrane transporters can influence the disposition of statins, e.g. the organic anion transporting polypeptide (OATP) 1B1 enhances their hepatic uptake. The c.521T>C (p.Val174Ala) genetic polymorphism of SLCO1B1 (encoding OATP1B1) considerably increases the plasma concentrations of simvastatin acid and moderately increases those of pravastatin but seems to have no significant effect on fluvastatin. Strong inhibitors of CYP3A (itraconazole, ritonavir) greatly (up to 20-fold) increase plasma concentrations of simvastatin, lovastatin and their active acid forms, thus enhancing the risk of myotoxicity. Weak or moderately potent CYP3A inhibitors such as verapamil, diltiazem and grapefruit juice can be used cautiously with low doses of simvastatin or lovastatin, but their concomitant use needs medical supervision. Potent inducers of CYP3A can greatly decrease plasma concentrations of simvastatin and simvastatin acid, and probably those of lovastatin and lovastatin acid. Although fluvastatin is metabolized by CYP2C9, its concentrations are changed less than 2-fold by inhibitors or inducers of CYP2C9. Pravastatin plasma concentrations are not significantly affected by any CYP inhibition and only slightly affected by inducers. Ciclosporin inhibits CYP3A, P-glycoprotein and OATP1B1. Gemfibrozil and its glucuronide inhibit CYP2C8 and OATP1B1. Ciclosporin and gemfibrozil increase plasma concentrations of statins and the risk of their myotoxicity, but fluvastatin seems to carry a smaller risk than other statins. Inhibitors of OATP1B1 may decrease the benefit-risk ratio of simvastatin, lovastatin and pravastatin by interfering with their (active acid forms) entry into hepatocytes. Understanding the differences in the pharmacokinetics and interaction potential of various statins helps in their selection for possible non-prescription status. On the pharmacokinetic basis, fluvastatin and pravastatin can be better choices than simvastatin or lovastatin for an OTC statin.

Gemfibrozil and its glucuronide inhibit the hepatic uptake of pravastatin mediated by OATP1B1

When pravastatin (40 mg/day) was co-administered with gemfibrozil (600 mg, b.i.d., 3 days) to man, the AUC of pravastatin increased approximately 2-fold. We have clarified that OATP1B1 is a key determinant of the hepatic uptake of pravastatin in humans. Thus, we hypothesized that gemfibrozil and the main plasma metabolites, a glucuronide (gem-glu) and a carboxylic acid metabolite (gem-M3), might inhibit the hepatic uptake of pravastatin and lead to the elevation of the plasma concentration of pravastatin. Gemfibrozil and gem-glu inhibited the uptake of 14C-pravastatin by human hepatocytes with Ki values of 31.7 µM and 15.7 µM, respectively and also inhibited pravastatin uptake by OATP1B1-expressing Xenopus laevis oocytes with Ki values of 15.1 µM and 7.6 µM. Additionally, we examined the biliary transport of pravastatin and demonstrated that pravastatin was transported by MRP2 using both human canalicular membrane vesicles (hCMVs) and human MRP2-expressing vesicles. However, gemfibrozil, gem-glu and gem-M3 did not affect the biliary transport of pravastatin by MRP2. Considering the plasma concentrations of gemfibrozil and gem-glu in humans, the inhibition of OATP1B1-mediated hepatic uptake of pravastatin by gem-glu would contribute, at least in part, to the elevation of plasma concentration of pravastatin by the concomitant use of gemfibrozil.

Influence of Drug Transporter Polymorphisms on Pravastatin Pharmacokinetics in Humans

The role of drug transporters in pravastatin disposition is underlined by the fact that pravastatin does not undergo significant cytochrome P-450 (CYP)-mediated biotransformation. The organic anion transporting polypeptide 1B1 (OATP1B1), encoded by SLCO1B1, and multidrug resistance-associated protein 2 [MRP2 (ABCC2)], are thought to be the major transporters involved in the pharmacokinetics of pravastatin in humans. Other transporters that may play a role include OATP2B1, organic anion transporter 3 (OAT3), bile salt export pump (BSEP), and the breast cancer resistance protein (BCRP). OATP1B1 and MRP2 mediate the hepatic uptake and biliary excretion of pravastatin, respectively. The SLCO1B1 and ABCC2 polymorphisms probably contribute to the high interindividual variability in pravastatin disposition. Recent small studies have characterized the impact of the SLCO1B1 polymorphism on pravastatin in humans, and especially the c.521T>C single-nucleotide polymorphism (SNP) seems to be an important determinant of pravastatin pharmacokinetics. Pravastatin plasma concentrations may be up to 100% higher in subjects carrying the c.521C variant, as found in the *5, *15, *16, and *17 haplotypes, reflecting diminished OATP1B1-mediated uptake into the major site of pravastatin elimination, the liver. The SLCO1B1 polymorphism seems to have a similar impact on the pharmacokinetics of single- and multiple-dose pravastatin. Overall, 2-5% of individuals in various populations may be expected to show markedly elevated plasma pravastatin concentrations due to the SLCO1B1 polymorphism. Of note, the impact of the SLCO1B1 polymorphism on statins may be dependent on ethnicity. Although individuals with a diminished hepatic uptake of pravastatin might be expected to show reduced cholesterol-lowering efficacy due to lower intracellular pravastatin concentrations, there is preliminary evidence to suggest that the SLCO1B1 polymorphism is not a major determinant of non-response to pravastatin. The possible consequences of drug transporter polymorphisms, especially the SLCO1B1 and ABCC2 polymorphisms, for the lipid-lowering efficacy and tolerability of pravastatin in various ethnic groups warrant further study.

Pharmacokinetics and response to pravastatin in paediatric patients with familial hypercholesterolaemia and in paediatric cardiac transplant recipients in relation to polymorphisms of the SLCO1B1 and ABCB1 genes

Our aim was to investigate associations between the single nucleotide polymorphisms (SNPs) in the SLCO1B1 (encoding OATP1B1) and ABCB1 (encoding P-glycoprotein) genes with the pharmacokinetics and efficacy of pravastatin in children with heterozygous familial hypercholesterolaemia (HeFH) and in paediatric cardiac transplant recipients. Twenty children with HeFH (aged 4.9-15.6 years) and 12 cardiac transplant recipients (aged 4.4-18.7 years and receiving triple immunosuppressive medication) who had participated in previous pharmacokinetic and pharmacodynamic studies with pravastatin were genotyped for the -11187G > A and 521T > C SNPs in the SLCO1B1 gene and for the 2677G > T/A and 3435C > T SNPs in the ABCB1 gene. Two HeFH patients with the -11187GA genotype had a 81% lower peak plasma pravastatin concentration (Cmax) (difference in means -13.9 ng ml(-1), 95% CI -21.1, -6.7; P < 0.001) and a 74% smaller area under the plasma concentration-time curve (AUC0, infinity) (-25.3 ng ml(-1) h, 95% CI -35.6, -15.0; P < 0.0001) and significantly greater increase in high density lipoprotein (HDL) cholesterol after 2 months treatment with pravastatin than patients with the reference genotype. No significant differences were seen in the pharmacokinetics or effects of pravastatin between HeFH patients with the SLCO1B1 521TC and 521TT genotypes. The cardiac transplant recipients with the SLCO1B1 521TC genotype (n = 3) had a 46% lower Cmax (-67.7 ng ml(-1), 95% CI -135.7, 0.3; P = 0.055) and 62% lower AUC(0,24 h) (-228.5 ng ml(-1) h, 95% CI -402.7, -54.3; P = 0.016) and a shorter half-life (t1/2) (0.9 +/- 0.1 vs. 1.3 +/- 0.4 h, P = 0.015) of pravastatin than those with the reference genotype. Decreases in total and low-density lipoprotein cholesterol by pravastatin were significantly smaller, and the increase in HDL-cholesterol was greater in the transplant recipients with the 521TC genotype compared with patients with the 521TT reference genotype. In children with HeFH and in paediatric cardiac transplant recipients receiving immunosuppressive medication, the -11187G > A and SLCO1B1 521T > C SNPs were associated with decreased plasma concentrations of pravastatin. These differences are opposite to those seen previously in healthy adults. The mechanisms underlying these phenomena are unclear and warrant further study.

Pharmacokinetic interaction between nelfinavir and pravastatin in HIV-seronegative volunteers: ACTG Study A5108

Nelfinavir, an HIV protease inhibitor with numerous drug-drug interactions, is associated with dyslipidemia. Pravastatin is the preferred statin prescribed for HIV-associated dyslipidemia. To examine the effect of nelfinavir on pravastatin pharmacokinetics. Open-label study in healthy HIV-seronegative adults conducted at the AIDS Clinical Trials Group sites in the United States. Subjects received pravastatin 40 mg daily and underwent intensive sampling for pharmacokinetics on day 3. Subjects took only nelfinavir 1250 mg twice daily on days 4-12. On days 13-15, subjects continued nelfinavir and reinitiated pravastatin. Plasma samples were collected over 24 h for the calculation of pravastatin area under the concentration-time curve for 0-24 h on days 3 and 16. Data from 14 subjects with complete pharmacokinetic samples were available for analysis. The median within-subject percentage change in pravastatin AUC was a decrease of 46.5%. Pravastatin maximum plasma concentrations were also lower when pravastatin was administered with nelfinavir. Median values for the maximum plasma concentrations were 27.9 and 12.4 ng/ml for days 3 and 16, respectively, and the median within-subject decrease was 40.1%. Coadministration of pravastatin and nelfinavir led to a substantial reduction in pravastatin plasma concentrations. Higher doses of pravastatin may need to be prescribed in order to achieve optimal lipid-lowering activity.

The Effects of Multiple Doses of Fenofibrate on the Pharmacokinetics of Pravastatin and Its 3α‐Hydroxy Isomeric Metabolite

Published data indicate that coadministration of multiple doses of the fibrate drug, gemfibrozil, led to a 202% increase in pravastatin systemic exposure (area under the plasma concentration-time curve, AUC). To evaluate the effects of another fibrate drug, fenofibrate, on the pharmacokinetics of pravastatin, 24 healthy subjects took pravastatin (40 mg once daily) on study days 1 to 15 and fenofibrate (160 mg once daily) on study days 6 to 15. Blood samples were collected for 24 hours after dosing on days 5, 6, and 15. Plasma concentrations of pravastatin and its active metabolite, 3alpha-hydroxy-iso-pravastatin, were measured, and pharmacokinetics was assessed. Safety assessments were based on adverse events, physical examinations, electrocardiogram results, vital signs, and clinical laboratory testing. Safety results were unremarkable. Coadministration of fenofibrate had modest effects on pravastatin and 3alpha-hydroxy-iso-pravastatin systemic exposures (AUC). Increases in pravastatin systemic exposures (19%-28%, on average) and 3alpha-hydroxy-iso-pravastatin systemic exposures (24%-39%, on average) were observed upon coadministration, but individual changes were variable. Pravastatin and 3alpha-hydroxy-iso-pravastatin systemic exposures were not statistically significantly different following the 1st and 10th doses of fenofibrate.

Pharmacokinetics and pharmacodynamics of pravastatin in pediatric and adolescent cardiac transplant recipients on a regimen of triple immunosuppression.

In adults, pravastatin reduces the development and progression of transplant vasculopathy, the main long-term risk after cardiac transplantation. The pharmacokinetics of pravastatin is not known in children taking calcineurin inhibitors. Our aim was to determine the single-dose pharmacokinetics and short-term safety of pravastatin in children undergoing regular triple-drug immunosuppressive therapy after cardiac transplantation. Nineteen pediatric cardiac transplant recipients (aged 4.4 to 18.9 years) receiving triple immunosuppression therapy consisting of methylprednisolone (19 patients), cyclosporine (INN, cyclosporin) (17 patients) or tacrolimus (2 patients), and azathioprine (18 patients) or mycophenolate mofetil (1 patient) ingested a single 10-mg dose of pravastatin, and plasma pravastatin concentrations were measured up to 24 hours. Subsequently, the patients took 10 mg pravastatin orally once daily for 8 weeks. The lipid-lowering effect and the safety of pravastatin therapy were studied. The mean peak plasma concentration (C(max)) of pravastatin was 122.2 +/- 88.2 ng/mL (range, 11.4-305.0 ng/mL), and the area under the plasma concentration-time curve of pravastatin from 0 to 10 hours [AUC(0-10)] was 264.1 +/- 192.4 ng.h/mL (range, 30.8-701.6 ng.h/mL). These C(max) and AUC(0-10) values are nearly 10-fold higher than the corresponding values reported in hypercholesterolemic children in the absence of immunosuppressive therapy. The time of peak concentration (t(max)) of pravastatin was 1.1 +/- 0.4 hours (range, 0.5-2 hours), and the mean elimination half-life (t(1/2)) was 1.2 +/- 0.3 hours (range, 0.7-2.2 hours); these parameters were similar to those in the hypercholesterolemic children. By 8 weeks of treatment, the concentration of serum total cholesterol decreased by 13% (P =.005), low-density lipoprotein cholesterol by 27% (P <.0001), and triglycerides by 6% (not significant, P =.28); the concentration of high-density lipoprotein cholesterol increased by 7% (not significant, P =.30). No clinically significant increases in serum ALT, creatine kinase, or creatinine levels were observed. The plasma concentrations of pravastatin in pediatric cardiac recipients receiving triple immunosuppressive medication are nearly 10-fold higher than in hypercholesterolemic children after the same pravastatin dose. However, the short-term therapy of pravastatin was well tolerated and effective in lowering serum cholesterol levels in cardiac recipients.

Determination of pravastatin by high performance liquid chromatography.

Pravastatin is a hydrophilic liver-specific inhibitor of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase. It effectively lowers plasma cholesterol and low-density lipoprotein concentrations in humans. Pharmacokinetic studies of pravastatin have been mostly performed by means of radioactively labelled drug or by measuring plasma concentrations with gas chromatography and mass spectrometry. Aim of our study was to develop a simple, but reliable method which allows the determination of pravastatin plasma concentrations under clinical routine conditions. Samples were prepared by solid-phase extraction on cyclohexyl bond elut cartridges. Chromatography was carried out on an octyl matrix. Triamcinolone acetonide was used as internal standard. The method was linear within the range of 5 to 200 microg/l pravastatin. The coefficient of variation depended on the pravastatin concentration, but was less than 10% throughout. The pharmacokinetics of pravastatin were determined in healthy individuals. Five healthy subjects received single oral doses of pravastatin (60 mg) and one of these subjects additionally received a dose of 80 mg at three different study days. In all subjects blood was sampled 0, 30, 60, 90, 120, 150, 180, 240 and 300 min after drug intake. Peak plasma concentrations of pravastatin were found between 60 min and 120 min after oral administration of 60 mg and reached values between 37 microg/l and 126 microg/l. The calculated AUCs were between 52 ng/ml x h and 311 ng/ml x h and the corresponding plasma elimination half-life times were between 95 min and 165 min. In all subjects plasma concentrations of pravastatin 5 hours after oral drug administration were near the detection limit of the method (5 microg/l). Intraindividually, there was only little variation in the kinetics of pravastatin. However, marked differences were encountered between the subjects studied. The data suggest that the determination of pravastatin plasma concentrations by means of a HPLC system can be used for routine analysis of pravastatin plasma concentrations. The obtained pharmacokinetic data in healthy individuals stand in ample agreement with the results of prior studies in which the concentrations of pravastatin were determined by other more sophisticated methods.

Clinical pharmacology of pravastatin, a selective inhibitor of HMG-CoA reductase

Pravastatin, lovastatin and simvastatin are HMG-CoA reductase inhibitors with very similar structures. However, minor substitutions in the decalin ring have resulted in major differences in physiocochemical, pharmacological, and pharmacokinetic properties. Both in vitro and in vivo studies have demonstrated that lovastatin and simvastatin are non-selective lipophilic inhibitors, while pravastatin is a selective hydrophilic inhibitor. An extensive clinical pharmacology program has been conducted for pravastatin. Radiolabelled studies demonstrated oral absorption and bioavailability values of 34% and 17%, respectively. The parent drug is cleared equally by renal and non-renal routes. Peak blood level after oral administration is reached at approximately 1 h and the mean plasma elimination half-life is 1.8 h. Binding of total radioactivity to plasma proteins averages 45%. Non-radiolabelled studies showed that mean areas under the plasma concentration-time curves (AUC) and maximum plasma concentrations (Cmax) are proportional to the doses administered, whereas times to reach Cmax (Tmax) and plasma elimination half-life values are independent of dose. Measurement of trough plasma concentrations of pravastatin at steady state showed no evidence of drug accumulation. Pharmacodynamic studies demonstrated an average LDL-C decrease of 30-35% at a daily dose of 40 mg. HDL-C increases are between 10% and 25% and triglyceride decreases, between 10% and 25%. These results indicate that pravastatin is very effective in lowering LDL-C. With its consistent decrease in triglycerides and increase in HDL-C, pravastatin offers a well-balanced lipid-modulating response.