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Background and Objective: MAMAdecoction (MD) is an antimalarial product prepared from the leaves of Mangifera indicaL. (Anacardiaceae), Alstonia booneiDe Wild (Apocynaceae), Morinda lucidaBenth (Rubiaceae) and Azadirachta indicaA. Juss (Meliaceae). A previous report showed that MD enhanced the efficacy of amodiaquine (AQ) in malaria-infected mice, thus suggesting a herb–drug interaction. The present study hence evaluated the effect of MD on the disposition of AQ in mice with a view to investigating a possible pharmacokinetic interaction. Methods: In a 3-period study design, three groups of mice (n= 72) were administered oral doses of AQ (10 mg/kg/day) alone, concurrently with MD (120 mg/kg/day), and in the 3rd period, mice were given AQ after a 3-day pre-treatment with MD. Blood samples were collected between 0 and 96 h for quantification of AQ and its major metabolite, desethylamodiaquine, by a validated high-performance liquid chromatography method. Results: Maximum concentrations of AQ increased by 12% with the concurrent dosing of MD and by 85% in the group of mice pre-treated with MD. The exposure and half-life of desethylamodiaquine increased by approximately 11% and 21%, respectively, with concurrent administration. Corresponding increases of approximately 20% and 33% of desethylamodiaquine were also observed in mice pre-treated with MD. Conclusion: MD influenced the pharmacokinetics of AQ and desethylamodiaquine, its major metabolite. The increase in the half-life and systemic exposure of AQ following its co-administration with MD may provide a basis for the enhanced pharmacological effect of the combination in an earlier study in Plasmodium-infected mice.

The Nigerian population exhibits huge ethnic and genetic diversity, typical of African populations, which can be harnessed for improved drug-response and disease management. Existing data on genes relevant to drug response, so far generated for the population, indeed confirm the prevalence of some clinically significant pharmacogenes. These reports detail prevailing genetic alleles and metabolic phenotypes of vital drug metabolizing monooxygenases, transferases and drug transporters. While the utilization of existing pharmacogenomic data for healthcare delivery remains unpopular, several past and on-going studies suggest that a future shift toward genotype-stratified dosing of drugs and disease management in the population is imminent. This review discusses the present state of pharmacogenomics in Nigeria and the potential benefits of sustained research in this field for the population.

Thiopurine S-methyltransferase (TPMT) methylates clinically relevant thiopurine drugs most of which are noted for adverse reactions in certain users, largely due to polymorphisms in the TPMTgene.