Effect of magnesium oxide on the activity of standard anti-epileptic drugs against experimental seizures in rats

OBJECTIVES: To study the effect of oral magnesium oxide supplementation alone and on the activity of standard anti-epileptic drugs in the animal models of maximal electroshock seizures (MES) and chemically (pentylenetetrazole [PTZ])-induced seizures. METHODS: Healthy male albino rats were given magnesium oxide (MgO) supplementation orally in various doses (500, 750 and 1000 mg/kg /day) for 4 weeks (day 1 to day 28). On day 0 and day 29, response to MES (180 mA for 0.2 s) was tested 1 h after pre-administration of phenytoin or carbamazepine orally. Similarly, in the other groups, the response to PTZ 40 mg/kg i.p. was tested 1 h after pre-administration of oral sodium valproate. RESULTS: Oral administration of MgO in a low dose (500 mg/kg) for 4 weeks in healthy rats appears to exert protective effect against MES. High oral doses of MgO (750 and 1000 mg/kg) appear to enhance the activity of phenytoin and carbamazepine in the MES model. MgO supplementation was seen to decrease the latency of PTZ-induced seizures. CONCLUSION: The dose of oral MgO appears to have an inverse relation with the protective effect in MES-induced seizure model. High doses of MgO supplementation given orally appear to enhance the activity of standard anti-epileptic drugs in the MES-induced seizure model.