Studies on reproduction in rats with pirmenol, an antiarrhythmic agent

Teratological assessment of stobadine after single and repeated administration in mice

Teratological studies were performed with stobadine, a compound with antiarrhythmic and antihypoxic activity. Single i.v. injections of stobadine in the form of dihydrochloride (DH 1011) to ICR mice on days 3, 6, 9 or 12 of gestation at doses of 1 and 3 mg kg-1 had no teratogenic effect. Slight fetal toxicity was manifested by decreased fetal weight after treatment on days 3 and 6, increased incidence of rudimentary ribs after treatment on days 9 and 12 of gestation and non-significantly increased postimplantation loss after injection on day 6 of gestation. The effect of repeated oral administration in the form of dipalmitate salt (DP 1031) was studied in doses of 12.2, 61.0 and 122.0 mg kg-1 on days 4-16 of gestation. Oral exposure to 61.0 mg kg-1 DP 1031 resulted in significant reduction of implantations, live fetuses and litter weight, and after 122.0 mg kg-1 DP 1031 the fetal weight was significantly decreased. External and skeletal examinations of the fetuses revealed no evidence of teratogenesis. The relevance of the two routes of stobadine administration for risk involvement is discussed.

Teratological study of stobadin after single and repeated administration in rats

The toxic developmental potential of the anti-arrhythmic drug stobadin was assessed after single intravenous or repeated oral doses to pregnant rats. Stobadin was studied in the form of dihydrochloride (DH 1011) at doses of 2 and 6 mg/kg, given in single intravenous injections on days 3, 6, 9, or 12 of gestation. Immediately after injection of the 6-mg/kg dose of DH 1011 to pregnant rats, saccade abdominal respiration, tremor of hindlimbs, and sedative behaviour were observed on each day of medication. No deaths of females occurred in either the control or experimental groups. Slight foetal toxicity was manifested by significantly decreased foetal weight only after treatment on day 3 of gestation at 6 mg/kg and by significantly increased incidence of delayed ossification of the parietal and supraoccipital bone also at 6 mg/kg DH 1011 given on day 12 of gestation. The effect of repeated oral treatment in the form of dipalmitate salt (DP 1031) was studied in doses of 5, 15, and 45 mg/kg from days 2-15 of gestation. Oral exposure to 45 mg/kg DP 1031 resulted in significant reduction of maternal body weight gain and in embryofoetal toxicity, namely, increased preimplantation foetal loss, anomalies of sternebrae, and, after 15 and 45 mg/kg DP 1031, significantly decreased foetal weight and smaller litter size. The relevance of the two routes of stobadin administration for risk extrapolation is discussed.

Preclinical toxicology of pirmenol hydrochloride

Pirmenol hydrochloride, a novel pyridinemethanol derivative, is a long-acting class Ia antiarrhythmic agent. Preclinical toxicology data were obtained in rat, mouse, dog and rabbit. In acute toxicity studies by oral and intravenous routes, no pathologic changes were observed in surviving mice, rats and dogs. In repeated dose toxicity studies, no drug-related pathologic changes were evident; dryness of the oral mucosa in dogs and body weight gain reductions in rodents were the only significant clinical signs. In a chronic (52 week) toxicity study in rats, pirmenol given in the diet was tolerated clinically at doses up to 100 mg/kg/day. No drug-related aberrations in clinical laboratory parameters or ophthalmic or pathologic findings were evident. In a similar study in beagle dogs, pirmenol was tolerated clinically at a dosage up to 30 mg/kg/day. No significant changes in biochemical, hematologic, urinary or bone marrow determinations were found in either species. In reproductive toxicology studies in rats, pirmenol had no significant effect on litter size or embryonic viability. In rabbits pirmenol had no effect on average litter size, embryonic viability or fetal wastage. Given to male rats, pirmenol had no overt effects on fertility. Pirmenol failed to elicit deoxyribonucleic acid damage or induce cytogenetic alterations. Pirmenol appears to be without significant limiting toxicologic properties.