Effect of Garcinia kola Heckel seeds on bioavailability of two commonly used drugs in nigeria (sulphamethazine and paracetamol)

Garcinia kola Heckel (Guttiferae), is a large forest tree found throughout Western and Central Africa. Widely known in commerce as 'bitter kola', the seeds are used extensively in African traditional medicine as a social masticatory agent and for the treatment of various diseases, especially cough, mouth and respiratory tract infections, and are also claimed to reduce the effectiveness of drugs and toxic substances in general. They are thus used locally as antidote to poisons and in cases of drug overdose. The effects of concurrent administration of G. kola whole seed suspension were investigated on the bioavailability of two commonly used drugs in Nigeria, namely, sulphamethazine, a sulphonamide antibiotic, and paracetamol, an analgesic and antipyretic, in albino rabbits. Two groups of rabbits (n=4 each) were treated by gavage with a concentration of 0.5g/kg body weight of seed suspension given concurrently with 150mg/kg body weight of sulphamethazine and paracetamol respectively. Control groups were given equivalent doses of either drug alone. Blood was withdrawn from the left ear at one hour intervals for five hours. Results showed that G. kola seeds decreased significantly (p<0.05) the bioavailability of the two drugs. Relative bioavailability was calculated to be 77.56% for sulphamethazine and 75.39% for paracetamol. The time of peak and peak concentrations were also reduced, while the concentration at one hour was only significantly different for paracetamol at p<0.05. These results suggest that G. kola seeds may reduce bioavailability by interfering with drug absorption across the gastrointestinal mucosa.

Acknowledgement: The Management and Staff of Emmanuel Research Laboratory, Enugu Nigeria for allowing the use of their facilities

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