Pravastatin sodium, a competitive inhibitor of HMG-CoA reductase, is a new orally effective hypocholesterolaemic agent. In a two-way crossover study, eight healthy male subjects each received an intravenous and an oral dose of [14C]-pravastatin sodium. The oral absorption of [14C] activity from pravastatin sodium was about 34% and the oral bioavailability was about 18%, suggesting first-pass metabolism of pravastatin. After the intravenous dose, the recovery of radioactivity averaged 60% and 34% in urine and faeces, respectively. Corresponding values were 20% (urine) and 71% (faeces) for the oral dose. The estimated average plasma elimination half-life of pravastatin was 0.8 and 1.8 h for the intravenous and oral routes, respectively. The average values for total and renal clearances were 13.5 and 6.3 ml min-' kg-', respectively, and the steady-state volume of distribution averaged 0.51 kg-1. These results suggest that both kidney and liver are important sites of elimination for pravastatin.
NBI-3001 appears to have an acceptable safety and toxicity profile when administered intratumorally in patients with recurrent malignant glioma.
The oral bioavailability of two HMG-CoA reductase inhibitors, pravastatin and lovastatin, was investigated in this randomized, two-way crossover study. Twenty healthy men were randomly assigned to treatment with a 40-mg dose of pravastatin or lovastatin once daily for 1 week; steady state kinetics were assessed after the last dose. After 1 week of washout, each subject received the alternate treatment. Serum specimens were assayed by gas chromatography/mass spectrometry (GC/MS) for intact pravastatin or lovastatin acid and by bioassay for active inhibitor concentration and, after hydrolysis of lactones, for total inhibitor concentration. The systemic bioavailabilities of total (active plus potentially active) inhibitors for the two drugs were different, with the mean AUC value for lovastatin being 50% higher than that of pravastatin (mean +/- SEM AUC0-24 values of 285 +/- 25 and 189 +/- 13 ng-equiv x hr/mL, respectively, P less than .0001). Pravastatin, which is administered as the monosodium salt, is present in the systemic circulation as the open acid; lovastatin, which is administered as the lactone, is present as both open-acid active metabolites (62%) and closed-ring lactone metabolites (38%), which are potentially active. Based on mean AUC values, pravastatin accounted for 75% of the active inhibitors from a pravastatin dose. Lovastatin acid accounted for just 25% of the active inhibitors from a lovastatin dose, with the remainder due to other active metabolites. Significant decreases from baseline in total and low-density lipoprotein (LDL) cholesterol were observed during the first treatment leg for both pravastatin and lovastatin.(ABSTRACT TRUNCATED AT 250 WORDS)
NBI-3001 is a novel immunotoxin of attenuated Pseudomonas exotoxin fused to circularly permutated IL-4, which has shown some antitumor effects in glioblastoma multiforme with intratumoral administration. The authors evaluated the safety and tolerability of NBI-3001 administered intravenously in a dose-escalation design to patients with renal cell and non-small cell lung carcinoma whose tumors showed at least 10% IL-4 receptor expression. Cohorts of three to six patients were treated at dose levels of 0.008, 0.016, and 0.027 mg/m2 daily x 5 days every 28 days. Neutralizing antibody (NAB) titers, plasma levels of NBI-3001, and patient tolerability were monitored sequentially. 14 patients received a total of 36 cycles of NBI-3001 (range 1-6). No dose-limiting toxicities were noted at dose levels 0.008 and 0.016 mg/m2. At 0.027 mg/m2, two patients developed self-limiting, grade 3 or 4 transaminase elevation during cycle 1. NAB titers of more than 1:100 were detected in five of the seven patients treated with at least two cycles; the median titer after cycle 1 and the median maximum titer in subsequent cycles were 1:50 and approximately 1:1,710, respectively. No objective tumor responses were noted. Eight of 12 evaluable patients with renal cell carcinoma had stable disease; four patients had disease progression. High NAB titers resulted in four patients being withdrawn from the study. The dose-limiting toxicity for intravenous NBI-3001 was transaminase elevation at 0.027 mg/m2. NBI-3001 at 0.016 mg/m2 was well tolerated. Low circulating levels of NBI-3001, coupled with rising NAB titers, may have contributed to the lack of response in tumors that express IL-4R.
The pharmacokinetics, pharmacodynamics, and safety of pravastatin, a new selective 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, were evaluated during monotherapy and with subsequent concomitant cholestyramine therapy in 33 patients with primary hypercholesterolemia in this randomized study. After 4 weeks, pravastatin monotherapy (5 mg, 10 mg, and 20 mg twice daily) significantly decreased total cholesterol by 17% to 24% (p less than 0.001 versus baseline) and low-density lipoprotein cholesterol by 23% to 35% (p less than 0.001). High-density lipoprotein cholesterol increased by 8% to 9%, and triglycerides decreased by 6% to 9%. The area under the serum concentration-time curve and maximum serum concentration of pravastatin showed dose-proportionality; time to maximum serum concentration and serum elimination half-life were independent of dose. When added to pravastatin therapy, cholestyramine enhanced the lipid-lowering effects of pravastatin. After 4 weeks of combination therapy, total cholesterol was reduced by 32% to 38% (p less than 0.001 versus baseline), and low-density lipoprotein cholesterol was reduced by 47% to 56% (p less than 0.001). High-density lipoprotein cholesterol increased by 11% to 18% (p less than 0.05). Pravastatin was well tolerated; no clinical adverse events directly attributable to the drug were reported.
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