Pharmacological Interaction of Centella asiatica and Bacopa monnieri with Anti-epileptic Drugs - an Experimental Study in Rats

Objective: The main objective of this study was to determine experimentally the pharmacological interaction of C.asiatica (CA) and B.monnieri (BM) with standard antiepileptic drugs (AEDs) such as Phenytoin (PHT), Phenobarbitone (PB) and Carbamazepine (CBZ) in rats. Methods: Adult, male Wistar rats were given either CA or BM (500 mg/kg) alone or in combination with one of the antiepileptic drugs (AEDs) at the ED₅₀ doses. The anticonvulsant activity was assessed by the classical Maximal Electro Shock (MES) test at 1, 3, 6 and 24 h after drug administration. Results: PHT and PB showed significant protection at 3 h (p < 0.05), whereas CBZ showed significant protection at 1, 3 and 6 h (p < 0.05). CA alone, showed protection from 1 - 24 h, with significant protection at 3 h (p < 0.05). When CA was combined with PHT, though seizure protection was seen, this effect was not statistically significant. When CA was combined with PB, the protective activity of PB declined from 50% to 0 % (p < 0.05) at 3 h. When CA was combined with CBZ, significant seizure protection was seen only at 1 and 3 h (p < 0.05). Similar to CA, the seizure protection of BM was significant only at 3h (p <0.05). In combination with AEDs significant seizure protection (p < 0.05) was observed - with PHT at 6 h, with PB at 3 h, and with CBZ, at 1, 3 and 6 h. Conclusion: This study demonstrated that herbal plant products such as CA and BM interact pharmacologically with standard AEDs and hence caution should be exercised to avoid any possible adverse interactions.