The <i>in vitro</i> Assessment of Drug Resistant Malaria In Makurdi, North Central Nigeria
Multi-drug resistant malaria parasite strains have spread to new areas that were once free of such strains. This study evaluated the specific in vitro sensitivities of some standard antimalarial drugs, against Plasmodium falciparum isolates in Makurdi, North Central Nigeria. The standard schizonts growth inhibition assays was used to study the in vitro activities of quinine, artesunate, and amodiaquine against 146 isolates in children aged 2-14 years. 100 % of isolates were in vitro sensitive to quinine, geometric mean effective concentration (EC)50 = 241.55 nM, EC90 = 676.08 nM, and EC99 = 993.12 nM; and artesunate, EC50 = 1.05 nM, EC90 = 2.42 nM, and EC99 = 3.16 nM. 1.37 % of isolates were resistant to amodiaquine, EC50 = 22.08 nM, EC90 = 66.22 nM and EC99 = 100.23 nM. Significant in vitro cross resistance was found at EC50 values of quinine-amodiaquine drug pair (r = + 0.342, P < 0.05), but not quinine – artesunate (r = + 0.057, P > 0.05) or artesunate-amodiaquine (r = + 0.088, P > 0.05). These results call for constant surveillance, to curb the spread of P. falciparum resistance to amodiaquine in Nigeria.