Qualitative and quantitative evaluation of prostatic histomorphology in rats following chronic treatment with finasteride, a 5-alpha reductase inhibitor.

Objective: To determine any potential direct and/or indirect effects of elevated intraprostatic T levels on the prostates of rats chronically (1-2 years) exposed to high doses (160 mg/kg/day) of finasteride, a selective inhibitor of 5-alpha reductase.

Methods: Sprague-Dawley male rats were administered daily finasteride by oral gavage. Prostates from all rats were weighed, fixed in 10% neutral buffered formalin, and processed for light microscopic examination.

The toxicity of a fluorinated-biphenyl HMG-CoA reductase inhibitor in beagle dogs.

L-645, 164, a potent inhibitor of hydroxymethylglutarylcoenzyme A (HMG-CoA) reductase, is a structurally unique, synthetic monofluorinated-biphenyl that was administered to beagle dogs at dosages of 2, 10, or 50 mg/kg/day for 14 weeks to evaluate its toxic potential. Previously tested HMG-CoA reductase inhibitors from this laboratory have either been semisynthetic or fermentation-derived products containing a hexahydronaphthalene ring structure (i.e.

Maternotoxicity and fetotoxicity of an angiotensin-converting enzyme inhibitor, enalapril, in rabbits.

When enalapril, an angiotensin-converting enzyme (ACE) inhibitor, was orally administered to inseminated rabbits at dosages of 0.1 to 30 mg/kg/day for 13 days in a range-finding study, nephrotoxicity, as measured by elevated serum urea nitrogen concentrations, occurred at 1 mg/kg/day and higher dosages and significant (p less than or equal to 0.05) increases in fetal wastage were observed at dosages as low as 3 mg/kg/day.

On the etiology of subcapsular lenticular opacities produced in dogs receiving HMG-CoA reductase inhibitors.

The administration of high dosages of various hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitors has resulted in the development of subcapsular lenticular opacities in dogs. While dogs receiving cataractogenic doses of HMG-CoA reductase inhibitors experienced profound decreases in circulating serum cholesterol concentrations (40-60% reductions in total serum cholesterol), a causal relationship between serum cholesterol lowering and cataractogenesis was not established. A strong relationship was demonstrated, however, between the systemic exposure to inhibitor (plasma drug levels) and the cataractogenic potential of the various compounds studied.

Animal safety and toxicology of simvastatin and related hydroxy-methylglutaryl-coenzyme A reductase inhibitors.

Simvastatin, a hydroxy-methylglutaryl-coenzyme A reductase inhibitor intended for use as a hypocholesterolemic agent, has undergone a thorough preclinical toxicology evaluation. This review describes preclinical toxicology findings associated with simvastatin administration in animals and provides the rationale for our conclusion that these changes are not indicative of potential human toxicity. Although it was not surprising to find that a potent inhibitor of this key biochemical pathway produces toxicity at high dosages in animals, none of the observed changes poses a significant risk to humans at clinical dosages.

Preclinical evaluation of lovastatin.

Administration of lovastatin to animals at high dosage levels produces a broad spectrum of toxicity. This toxicity is expected based on the critical nature of the target enzyme (HMG CoA reductase) and the magnitude of the dosage levels used. The information reviewed in this paper demonstrates that these adverse findings in animals do not predict significant risk in humans.

Association between adverse maternal and embryo-fetal effects in norfloxacin-treated and food-deprived rabbits.

Norfloxacin is a new antibiotic which caused embryo-fetal toxicity in association with maternotoxicity when given orally to rabbits at 100 mg/kg/day. The intestinal flora of rabbits is unusually sensitive to many antibiotics and it was suspected that the maternotoxicity and embryo-fetal toxicity caused by oral norfloxacin were secondary to an effect on the intestinal flora. To test this idea, a teratologic study was conducted in which rabbits were dosed on Days 6 to 18 of gestation with norfloxacin given orally at 100 mg/kg/day or subcutaneously at 20 mg/kg/day.

Famotidine: summary of preclinical safety assessment.

Extensive preclinical safety studies with famotidine were performed or sponsored by Yamanouchi Phamaceutical Co, Ltd, Tokyo, Japan, and Merck, Sharp & Dohme Research Laboratories, West Point, Pennsylvania, USA. These studies were performed in dogs, rats, mice and rabbits, receiving oral and intravenous administration of the compound. Minimal toxicologic effects (after acute, subacute, or chronic administration) have been observed even at extremely high dosage levels (4,000 mg/kg/day) and for extended periods of administration (2,000 mg/kg/day for 105 weeks).

Diflunisal-induced maternal anemia as a cause of teratogenicity in rabbits.

Diflunisal [5-(2,4-difluorophenyl)-salicylic acid] is a new analgesic antiinflammatory drug that, when administered orally to rabbits at 40 and 60 mg/kg/day, caused terata, most commonly axial skeletal defects. These same dosage levels also caused a severe maternal hemolytic anemia following a dramatic decrease in erythrocyte ATP levels. The teratogenicity, anemia, and depletion of ATP were unique to the rabbit among species examined.

Two inhibitors of angiotensin-converting enzyme, enalapril and captopril, increase salt appetite of rats.

Male rats were orally administered an inhibitor of angiotensin-converting enzyme (ACE), N-[(S)-1-(ethoxycarbonyl)-3-phenylpropyl]-1-ala-1-pro maleate (enalapril, MK-0421) at dosage levels of 10, 30, and 90 mg/kg X d. After 2-6 wk of dosing, the rats receiving 30 and 90 mg/kg X d produced large numbers of seminal plugs and had lacerated penises due to licking in an attempt to recover urine. Providing 0.

Mevalonate supplementation in pregnant rats suppresses the teratogenicity of mevinolinic acid, an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme a reductase.

Mevinolin is a fungal metabolite, and in the hydroxyacid form, mevinolinic acid, it is an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-Co A) reductase, an enzyme essential in cholesterol biosynthesis. Oral administration of 800 mg/kg/day of mevinolin to rats from days 6 through 17 of gestation produced fetal malformations of the vertebrae and ribs in 29% of the litters, and there was a treatment-related increase in the incidence of gastroschisis. Mevinolinic acid at 60 and 90 mg/kg/day also produced fetal malformations of the vertebrae and ribs, and these teratogenic manifestations were markedly suppressed by coadministration of the product of HMG-Co A reductase, mevalonic acid, at a dosage level of 500 mg/kg b.

Spontaneous tumors in control F344 and charles river-CD rats and Charles River CD-1 and B6C3HF1 mice.

The incidence of spontaneous neoplasms in outbred, inbred and F1 hybrid strains was compared using the Charles River-CD rat and mouse, the F344 rat, and B6C3HF1 mouse. These strains are commonly used in carcinogenic studies. Each strain has a consistent pattern of tumor occurrence; testicular, pituitary and lymphoreticular neoplasms are common in F344 rats, mammary and pituitary neoplasms are common in Charles River-CD rats, liver neoplasms are uncommon in CD-1 mice, while hepatic tumors are frequent in male B6C3HF1 mice.

Exposure of rats to lead nitrate in utero or postpartum; effects on morphology and behavior.

Female rats were administered lead (Pb), as the nitrate salt, on day 17 of pregnancy (5 or 25 mg/kg i.v.) or throughout lactation (5 or 25 mg/kg/day p.

Aspirin: teratogenic evaluation in the dog.

Beagle bitches were administered aspirin at either 100 or 400 mg/kg/day between Days 15 and 22 or Days 23 and 30 postmating, and corresponding control groups were dosed with vehicle during one of these same time periods. Maternotoxicity was evident in all dogs dosed with 400 mg/kg/day of aspirin, but no signs of toxicity were observed when 400 mg/kg/day of aspirin was administered from Days 15 to 22 postmating. Teratogenicity, as evidenced by 50% malformation rate, was seen in fetuses from dams treated with 400 mg/kg/day on Days 23 to30 postmating.

Morphologic abnormalities in potassium-deficient dogs.

Potassium deficiency was produced in 16 dogs by means of a diet containing less than 0.03% potassium. Decreases in serum potassium were first observed after 3 weeks.

Pharmacology and toxicology of diflunisal.

Diflunisal, a new salicylate, possesses anti-inflammatory, analgesic and antipyretic activity. It was found to be about 7.5-13 times more active than aspirin as an analgesic (Randall-Selitto assay in rats) and as an anti-inflammatory agent (carrageenin foot oedema and adjuvant arthritis in rats).