Teratological study of stobadin after single and repeated administration in rats

Effect of Rythmol (propafenone HCl) administration during pregnancy in Wistar rats

Propafenone is a well-known Class 1C antiarrhythmic agent that has sodium channel blocking properties as well as the ability to block 13 other channels and a modest calcium antagonistic effect. Propafenone has a profound electrophysiologic effect on auxiliary atrioventricular circuits and in patients with atrioventricular nodal reentry tachycardia can obstruct conduction in the fast conducting pathway. Furthermore, propafenone is less likely than other Class 1C drugs to cause proarrhythmia. However, although this medicine can pass through the placenta, the effects during pregnancy remain unknown. Here, we investigated the potential teratogenic and genotoxic effects of Rythmol during rat development. Pregnant Wistar rats received 46.25 mg/kg body weight of propafenone daily by gavage from Gestation Day (GD) 5 to GD 19. At GD 20, the dams were dissected, and their fetuses were assessed via morphologic, skeletal, and histologic investigation. In addition, a comet assay was used to measure DNA impairment of fetal skull osteocytes and hepatic cells. The study showed that propafenone treatment of pregnant rats led to a marked decrease in gravid uterine weight, number of implants/litter, number of viable fetuses, and bodyweight of fetuses but a clear increase in placental weight and placental index in the treated group. Frequent morphologic abnormalities and severe ossification deficiency in the cranium bones were observed in the treatment group. Various histopathological changes were observed in the liver, kidney, and brain tissues of maternally treated fetuses. Similarly, propafenone induced DNA damage to examined samples. Thus, our study indicates that propafenone may be embryotoxic in humans.

Safety assessment of the pyridoindole derivative SMe1EC2: developmental neurotoxicity study in rats

The present study deals with effect of prenatal and neonatal administration of the synthetic pyridoindole derivative SMe1EC2 (2-ethoxycarbonyl-8-methoxy-2,3,4,4a,5,9b-hexahydro-1H-pyrido-[4,3b] indolinium chloride) on postnatal and neurobehavioral development of the rat offspring. The substance tested was administered to pregnant rats orally in the doses 5, 50 and 250 mg/kg from day 15 of gestation to day 10 post partum (PP). From the day 4 PP, the postnatal development and neurobehavioral characteritics of offspring were evaluated. The following variables were observed: body weight, pinna detachment, incisor eruption, ear opening, eye opening, testes descent and vaginal opening, righting reflex, negative geotaxia, startle reflex, dynamic air righting and exploratory behavior in a new environment. No maternal death, abortion or dead fetuses occurred either in the control or SMe1EC2 groups. Dynamic righting reflex was delayed one day in the groups of animals treated via their mothers with 5 and 50 mg/kg SMe1EC2. The delay in the development of this reflex was only transient. On day 20 PP, all pups tested had a positive score of the reflex. Administration of SMe1EC2 did not reveal any significant changes in other variables of somatic growth and maturation, reflex and neuromotor development and exploratory behavior, either of young or adult animals of both genders, assessed by analysis of variance.

Evaluation of long-term administration of the antioxidant stobadine on exploratory behaviour in rats of both genders

Stobadine (STO) is a prospective neuro- and cardioprotective drug with high antioxidative properties. The aim of this study was to ascertain the effect of long-term administration of STO on exploratory behaviour and habituation processes in adult virgin female and male rats. Stobadine was administered by oral gavage in a single dose of 50 mg kg(-1) day(-1) for a total of 56 days. The animals were tested for exploratory behaviour-intensity of motor and vertical activity in an open field test in three blocks of measurements (initial screening; after 56 days of STO administration; and 28 days after the last treatment). The rate of decline of motor activity was evaluated during four consecutive days of testing (interrupted habituation). Administration of STO resulted in transient inhibition of exploratory behaviour in female rats without overtly detectable toxicity. Exploratory behaviour of males was not affected by STO treatment.

Antioxidant and pharmacodynamic effects of pyridoindole stobadine

1. The review summarizes the most important data known so far on chemistry, pharmacodynamics, toxicology and clinics of the investigational agent, pyridoindole stobadine. 2. Stobadine was shown to be able to scavenge hydroxyl, peroxyl and alkoxyl radicals, to quench singlet oxygen, to repair oxidized amino acids and to preserve oxidation of SH groups by one-electron donation. These effects originated from its ability to form a stable nitrogen-centered radical on indole nitrogen. Consequently, it was able to diminish lipid peroxidation and protein impairment under oxidative stress. 3. In various in vitro and in vivo animal models, stobadine was shown to diminish the impairment of the myocardium induced by mechanisms involving reactive oxygen species (e.g., myocardial infarction, hypoxia/ reoxygenation, catecholamine overexposure). 4. The neuroprotective effect of stobadine was demonstrated in a series of in vivo and in vitro models (brain in situ, brain slices, spinal cord, autonomic ganglia, etc.) during ischemia/reperfusion and hypoxia/ reoxygenation or in the presence of chemical systems generating free oxygen radicals, and so forth. Stobadine improved animal survival rate and synaptic transmission recovery, maintained SH tissue level and diminished lipid peroxidation as well as impairment of Ca-sequestering intracellular systems. 5. Oxidation of low-density lipoproteins (LDLs), which plays a major role in the development of atherosclerosis, was decreased by stobadine in vitro. Both lipid and protein (apo B) components of LDL were protected against Cu(2+)-induced oxidation by this agent. 6. Stobadine proved to be an effective protectant in models of free radical pathology in vivo, such as cyclophosphamide-, MNNG- or 60Co-induced mutagenesis and alloxan-induced hyperglycemia. 7. Besides other remarkable pharmacodynamic effects, stobadine exerts antidysrhythmic, local anesthetic, alpha-adrenolytic, antihistaminic, myorelaxant and antiulcerogenic actions. 8. Pharmacokinetic analyses demonstrated that stobadine was readily absorbed from the gastrointestinal tract. Thanks to its balanced lipo-hydrophilic properties, it was distributed over both water and lipid phases in biological tissues. It was shown to easily penetrate the blood-brain barrier. 9. Acute, subchronic and chronic toxicity studies in several animal species, as well as numerous analyses of embryotoxicity, teratogenicity, mutagenicity and genotoxicity, revealed only a negligible toxic potential of this agent. 10. Phase-one clinical study demonstrated safety of the compound. Only slight side effects--namely, a slight hypotension and a slight sedative effect--were observed subsequent to the highest dose used. In phase-two clinical study, the patients with angina pectoris treated for 4 weeks with stobadine showed a significant decrease in the frequency of anginal attacks, in the number of self-administrations of sublingual nitroglycerine and in plasma lipoprotein, cholesterol and triglyceride levels. A slight decrease in systolic and diastolic blood pressure also was observed. 11. It is suggested that stobadine may be considered a contribution to the search for new effective cardio- and neuroprotectants based on antioxidant or free radical scavenging mechanisms of action.

Inhibition of alloxan-induced hyperglycaemia in mice by the pyridoindole stobadine

Alloxan-induced hyperglycaemia was used as a model of free radical pathology to test the antioxidant activity of the pyridoindole drug, stobadine, in the intact mouse. Stobadine was injected intraperitoneally in a dose range 7.5-60 mg/kg prior to intravenous injection of alloxan (50 mg/kg), and blood glucose concentration 72 hr after alloxan administration was used as an index of alloxan toxicity. Stobadine efficiently suppressed the alloxan-induced hyperglycaemia in a dose-dependent manner. This protection against the diabetogenic effect of alloxan is consistent with the high efficacy of stobadine to scavenge hydroxyl radicals.

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.