PRAVASTATIN SODIUM (Page 5 of 7)

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

In a 2-year study in rats fed pravastatin at doses of 10, 30, or 100 mg/kg body weight, there was an increased incidence of hepatocellular carcinomas in males at the highest dose (p<0.01). These effects in rats were observed at approximately 12 times the human dose (HD) of 80 mg based on body surface area (mg/m2) and at approximately 4 times the HD, based on AUC.

In a 2-year study in mice fed pravastatin at doses of 250 and 500 mg/kg/day, there was an increased incidence of hepatocellular carcinomas in males and females at both 250 and 500 mg/kg/day (p<0.0001). At these doses, lung adenomas in females were increased (p=0.013). These effects in mice were observed at approximately 15 times (250 mg/kg/day) and 23 times (500 mg/kg/day) the HD of 80 mg, based on AUC. In another 2-year study in mice with doses up to 100 mg/kg/day (producing drug exposures approximately 2 times the HD of 80 mg, based on AUC), there were no drug-induced tumors.

No evidence of mutagenicity was observed in vitro, with or without rat-liver metabolic activation, in the following studies: microbial mutagen tests, using mutant strains of Salmonella typhimurium or Escherichia coli; a forward mutation assay in L5178Y TK +/− mouse lymphoma cells; a chromosomal aberration test in hamster cells; and a gene conversion assay using Saccharomyces cerevisiae. In addition, there was no evidence of mutagenicity in either a dominant lethal test in mice or a micronucleus test in mice.

In a fertility study in adult rats with daily doses up to 500 mg/kg, pravastatin did not produce any adverse effects on fertility or general reproductive performance.

13.2 Animal Toxicology and/or Pharmacology

CNS Toxicity

CNS vascular lesions, characterized by perivascular hemorrhage and edema and mononuclear cell infiltration of perivascular spaces, were seen in dogs treated with pravastatin at a dose of 25 mg/kg/day. These effects in dogs were observed at approximately 59 times the HD of 80 mg/day, based on AUC. Similar CNS vascular lesions have been observed with several other drugs in this class.

A chemically similar drug in this class produced optic nerve degeneration (Wallerian degeneration of retinogeniculate fibers) in clinically normal dogs in a dose-dependent fashion starting at 60 mg/kg/day, a dose that produced mean plasma drug levels about 30 times higher than the mean drug level in humans taking the highest recommended dose (as measured by total enzyme inhibitory activity). This same drug also produced vestibulocochlear Wallerian-like degeneration and retinal ganglion cell chromatolysis in dogs treated for 14 weeks at 180 mg/kg/day, a dose which resulted in a mean plasma drug level similar to that seen with the 60 mg/kg/day dose.

When administered to juvenile rats (postnatal days [PND] 4 through 80 at 5-45 mg/kg/day), no drug related changes were observed at 5 mg/kg/day. At 15 and 45 mg/kg/day, altered body- weight gain was observed during the dosing and 52-day recovery periods as well as slight thinning of the corpus callosum at the end of the recovery period. This finding was not evident in rats examined at the completion of the dosing period and was not associated with any inflammatory or degenerative changes in the brain. The biological relevance of the corpus callosum finding is uncertain due to the absence of any other microscopic changes in the brain or peripheral nervous tissue and because it occurred at the end of the recovery period.

Neurobehavioral changes (enhanced acoustic startle responses and increased errors in water- maze learning) combined with evidence of generalized toxicity were noted at 45 mg/kg/day during the later part of the recovery period. Serum pravastatin levels at 15 mg/kg/day are approximately 1 times (AUC) the maximum pediatric dose of 40 mg. No thinning of the corpus callosum was observed in rats dosed with pravastatin (250 mg/kg/day) beginning PND 35 for 3 months suggesting increased sensitivity in younger rats. PND 35 in a rat is approximately equivalent to an 8- to 12-year-old human child. Juvenile male rats given 90 times (AUC) the 40 mg dose had decreased fertility (20%) with sperm abnormalities compared to controls.

14 CLINICAL STUDIES

14.1 Prevention of Coronary Heart Disease

In the Pravastatin Primary Prevention Study (WOS),3 the effect of Pravastatin Sodium on fatal and nonfatal CHD was assessed in 6595 men 45 to 64 years of age, without a previous MI, and with LDL-C levels between 156 to 254 mg/dL (4-6.7 mmol/L). In this randomized, double-blind, placebo-controlled study, patients were treated with standard care, including dietary advice, and either Pravastatin Sodium 40 mg daily (N=3302) or placebo (N=3293) and followed for a median duration of 4.8 years. Median (25th , 75th percentile) percent changes from baseline after 6 months of pravastatin treatment in Total-C, LDL-C, TG, and HDL-C were −20.3 (−26.9, −11.7), −27.7 (−36.0, −16.9), −9.1 (−27.6, 12.5), and 6.7 (−2.1, 15.6), respectively.

Pravastatin Sodium significantly reduced the rate of first coronary events (either CHD death or nonfatal MI) by 31% (248 events in the placebo group [CHD death=44, nonfatal MI=204] versus 174 events in the Pravastatin Sodium group [CHD death=31, nonfatal MI=143], p=0.0001 [see figure below]). The risk reduction with Pravastatin Sodium was similar and significant throughout the entire range of baseline LDL cholesterol levels. This reduction was also similar and significant across the age range studied with a 40% risk reduction for patients younger than 55 years and a 27% risk reduction for patients 55 years and older. The Pravastatin Primary Prevention Study included only men, and therefore it is not clear to what extent these data can be extrapolated to a similar population of female patients.

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Pravastatin Sodium also significantly decreased the risk for undergoing myocardial revascularization procedures (coronary artery bypass graft [CABG] surgery or percutaneous transluminal coronary angioplasty [PTCA]) by 37% (80 vs 51 patients, p=0.009) and coronary angiography by 31% (128 vs 90, p=0.007). Cardiovascular deaths were decreased by 32% (73 vs 50, p=0.03) and there was no increase in death from non-cardiovascular causes.

14.2 Secondary Prevention of Cardiovascular Events

In the LIPID4 study, the effect of Pravastatin Sodium, 40 mg daily, was assessed in 9014 patients (7498 men; 1516 women; 3514 elderly patients [age ≥65 years]; 782 diabetic patients) who had experienced either an MI (5754 patients) or had been hospitalized for unstable angina pectoris (3260 patients) in the preceding 3 to 36 months. Patients in this multicenter, double-blind, placebo-controlled study participated for an average of 5.6 years (median of 5.9 years) and at randomization had Total-C between 114 and 563 mg/dL (mean 219 mg/dL), LDL-C between 46 and 274 mg/dL (mean 150 mg/dL), TG between 35 and 2710 mg/dL (mean 160 mg/dL), and HDL-C between 1 and 103 mg/dL (mean 37 mg/dL). At baseline, 82% of patients were receiving aspirin and 76% were receiving antihypertensive medication. Treatment with Pravastatin Sodium significantly reduced the risk for total mortality by reducing coronary death (see Table 5). The risk reduction due to treatment with Pravastatin Sodium on CHD mortality was consistent regardless of age. Pravastatin Sodium significantly reduced the risk for total mortality (by reducing CHD death) and CHD events (CHD mortality or nonfatal MI) in patients who qualified with a history of either MI or hospitalization for unstable angina pectoris.

Table 5: LIPID — Primary and Secondary Endpoints
Number (%) of Subjects
Event Pravastatin 40 mg (N=4512) Placebo (N=4502) Risk Reduction p -value
Primary Endpoint
CHD mortality 287 (6.4) 373 (8.3) 24% 0.0004
Secondary Endpoints
Total mortality 498 (11.0) 633 (14.1) 23% <0.0001
CHD mortality or nonfatal MI 557 (12.3) 715 (15.9) 24% <0.0001
Myocardial revascularization procedures (CABG or PTCA) 584 (12.9) 706 (15.7) 20% <0.0001
Stroke
All-cause 169 (3.7) 204 (4.5) 19% 0.0477
Non-hemorrhagic 154 (3.4) 196 (4.4) 23% 0.0154
Cardiovascular mortality 331 (7.3) 433 (9.6) 25% <0.0001

In the CARE5 study, the effect of Pravastatin Sodium, 40 mg daily, on CHD death and nonfatal MI was assessed in 4159 patients (3583 men and 576 women) who had experienced a MI in the preceding 3 to 20 months and who had normal (below the 75th percentile of the general population) plasma total cholesterol levels. Patients in this double-blind, placebo-controlled study participated for an average of 4.9 years and had a mean baseline Total-C of 209 mg/dL. LDL-C levels in this patient population ranged from 101 to 180 mg/dL (mean 139 mg/dL). At baseline, 84% of patients were receiving aspirin and 82% were taking antihypertensive medications. Median (25th , 75th percentile) percent changes from baseline after 6 months of pravastatin treatment in Total-C, LDL-C, TG, and HDL-C were −22.0 (−28.4, −14.9), −32.4 (−39.9, −23.7), −11.0 (−26.5, 8.6), and 5.1 (−2.9, 12.7), respectively. Treatment with Pravastatin Sodium significantly reduced the rate of first recurrent coronary events (either CHD death or nonfatal MI), the risk of undergoing revascularization procedures (PTCA, CABG), and the risk for stroke or TIA (see Table 6).

Table 6: CARE — Primary and Secondary Endpoints
*
The risk reduction due to treatment with Pravastatin Sodium was consistent in both sexes.
Number (%) of Subjects
Event Pravastatin 40 mg (N=2081) Placebo (N=2078) Risk Reduction p -value
Primary Endpoint
CHD mortality or nonfatal MI * 212 (10.2) 274 (13.2) 24% 0.003
Secondary Endpoints
Myocardial revascularization procedures (CABG or PTCA) 294 (14.1) 391 (18.8) 27% <0.001
Stroke or TIA 93 (4.5) 124 (6.0) 26% 0.029

In the PLAC I6 study, the effect of pravastatin therapy on coronary atherosclerosis was assessed by coronary angiography in patients with coronary disease and moderate hypercholesterolemia (baseline LDL-C range: 130-190 mg/dL). In this double-blind, multicenter, controlled clinical trial, angiograms were evaluated at baseline and at 3 years in 264 patients. Although the difference between pravastatin and placebo for the primary endpoint (per-patient change in mean coronary artery diameter) and 1 of 2 secondary endpoints (change in percent lumen diameter stenosis) did not reach statistical significance, for the secondary endpoint of change in minimum lumen diameter, statistically significant slowing of disease was seen in the pravastatin treatment group (p=0.02).

In the REGRESS7 study, the effect of pravastatin on coronary atherosclerosis was assessed by coronary angiography in 885 patients with angina pectoris, angiographically documented coronary artery disease, and hypercholesterolemia (baseline total cholesterol range: 160-310 mg/dL). In this double-blind, multicenter, controlled clinical trial, angiograms were evaluated at baseline and at 2 years in 653 patients (323 treated with pravastatin). Progression of coronary atherosclerosis was significantly slowed in the pravastatin group as assessed by changes in mean segment diameter (p=0.037) and minimum obstruction diameter (p=0.001).

Analysis of pooled events from PLAC I, PLAC II,8 REGRESS, and KAPS9 studies (combined N=1891) showed that treatment with pravastatin was associated with a statistically significant reduction in the composite event rate of fatal and nonfatal MI (46 events or 6.4% for placebo versus 21 events or 2.4% for pravastatin, p=0.001). The predominant effect of pravastatin was to reduce the rate of nonfatal MI.

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