Influence of caffeine on the protective activity of gabapentin and topiramate in a mouse model of generalized tonic-clonic seizures.

BACKGROUND

Caffeine may interact with classical antiepileptic drugs (AEDs), reducing their anticonvulsant effects in basic seizure models. The aim of the present study was to ascertain whether intraperitoneal caffeine (acute or chronic for 15 days) could attenuate the anticonvulsant effect of some newer AEDs: gabapentin (GBP) and topiramate (TPM) against electroconvulsions in mice.

METHODS

Maximal electroshock (MES)-induced mouse seizure model was used for the estimation of the anticonvulsant activity of TPM whilst the protective activity of GBP was evaluated in the threshold test for maximal (tonic) convulsions. Adverse effects were evaluated by measurement of long-term memory (the step-through passive avoidance task) and motor coordination (chimney test). Plasma AED concentrations were also measured to determinate any pharmacokinetic contribution to the observed effects.

RESULTS

Caffeine (both acute and chronic at 23.1 and 46.2mg/kg) significantly reduced the protective effects of TPM against MES. As regards GBP, caffeine (acutely at 46.2mg/kg and chronically at 23.1 or 46.2mg/kg) significantly diminished the GBP-induced increases in the electroconvulsive threshold. In addition, caffeine did not affect the free plasma concentrations of TPM or GBP. Acute and chronic caffeine (23.1 and 46.2mg/kg) enhanced the impairment of motor coordination in mice pretreated with GBP whilst an opposite effect was observed in TPM injected mice and pretreated with chronic caffeine at 46.2mg/kg.

CONCLUSION

The results indicate that newer AEDs, GBP or TPM behave in the exactly same way as classical antiepileptics in mice challenged with caffeine. This hazardous effect of caffeine is not subject to tolerance.