ralitoline and Seizures

The developmental toxicity of the anticonvulsant compound, ralitoline, was investigated in Sprague-Dawley rats administered oral doses of 0, 15, 60, 120, 180, or 240 mg/kg on days 6 through 15 of gestation. An untreated control group and a vehicle control group pair-fed to the high dose group were included. Maternal and fetal parameters were evaluated on day 21 of gestation. Fetuses were examined for external, visceral, and skeletal malformations and variations. Maternal death occurred at 180 and 240 mg/kg. Dose-dependent decreases in body weight, food consumption, and water consumption were observed at 60 mg/kg and above. Body weight gain during treatment was similar in the pair-fed and 240 mg/kg groups. Dose-related CNS signs (hypoactivity, ataxia, prostration, and/or convulsions) were observed at 60 mg/kg and above. Decreased numbers of live fetuses and increased postimplantation loss were observed in a dose-related manner at 120, 180, and 240 mg/kg while no changes occurred in pair-fed controls. Fetal body weights and placental weights were decreased in pair-fed controls and in the 120, 180, and 240 mg/kg groups. The percent fetuses per litter, and the percent litters with external/visceral malformations, were significantly increased at 120, 180, and 240 mg/kg compared with vehicle and pair-fed controls. Dose-related increases in cardiovascular malformations, specifically of the aortic arch (interrupted, stenotic, extra vessel), were apparent at 120 mg/kg and above. The incidence of skeletal variations was increased at 120 mg/kg and above.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Abnormalities, Drug-Induced; Animals; Anorexia; Anticonvulsants; Aorta, Thoracic; Ataxia; Bone and Bones; Dose-Response Relationship, Drug; Female; Fetal Growth Retardation; Fetal Resorption; Lethal Dose 50; Pregnancy; Pregnancy Complications; Rats; Rats, Sprague-Dawley; Seizures; Thiazoles; Weight Gain

Ralitoline, a thiazolidinone derivative chemically distinct from known antiepileptic drugs, possesses remarkable anticonvulsant properties as demonstrated in various animal models of epilepsy. The efficacy of this compound seems to be comparable or even better than that of conventional antiepileptics. In the present study, the activity of ralitoline was investigated in four seizure models in rodents in order to characterize the anticonvulsant profile of action further. In the maximal electroshock seizure test (mice), this compound showed marked anticonvulsant effects (ED50 2.8 mg/kg i.p.). The efficacy of clinically established anti-epileptics was significantly increased when ralitoline was given as co-medication. In the strychnine seizure test (mice), ralitoline (5 and 10 mg/kg) prolonged the latency of tonic seizures as well as the survival time. On the other hand, in the subcutaneous pentylenetetrazol seizure threshold test (mice), this drug revealed limited protective actions at higher doses and increased the effectiveness of ethosuximide. In unrestrained rats with chronically implanted electrodes, ralitoline (5 mg/kg) significantly reduced the duration of electrically-evoked hippocampal discharges and raised the focal stimulation threshold (10 mg/kg). In the rotorod ataxia test (mice), a TD50 value of 14.5 mg/kg i.p. was determined for ralitoline (protective index TD50/MES-ED50 5.2). With regard to the possible mode of action, whole-cell voltage-clamp experiments on cultured neonatal rat cardiomyocytes showed that ralitoline may act specifically on voltage-sensitive sodium channels. The compound inhibited the fast sodium inward current in a frequency- and voltage-dependent manner. In conclusion, the findings confirm the potent anticonvulsant effects of ralitoline, especially against generalized tonic-clonic and complex partial seizures. Moreover, in combination with antiepileptics, an additive synergism can be found at lower concentrations. Regarding the mode of action, this drug was capable of depressing the fast sodium inward current in cultured heart ventricular cells, suggesting that the local anesthetic properties may be important for the anticonvulsant activity of ralitoline.

Topics: Animals; Anticonvulsants; Brain; Cells, Cultured; Electric Stimulation; Male; Mice; Models, Biological; Motor Activity; Pentylenetetrazole; Phenobarbital; Rats; Rats, Wistar; Seizures; Sodium Channels; Strychnine; Thiazoles