Evaluation of antimalarial prescription pattern and susceptibility of <i>Plasmodium falciparum</i> isolates in Kaduna, Nigeria

Nigeria carries the highest burden of malaria in terms of morbidity and mortality. This is compounded by continuous resistance of Plasmodium falciparum to antimalarial drugs. This study was designed to evaluate the profile of malaria patients’ antimalarial drug prescription and in vitro susceptibility of P. falciparum isolates to commonly prescribed antimalarial drugs in Kaduna, Nigeria. Three years’ records of patients antimalarial drug prescriptions were collated (2013 to 2015) and the in vitro antimalarial agent susceptibility was determined for 28 clinical isolates using WHO Mark III microtest. Artemisinin-based combination therapy (ACT) was the most prescribed antimalarial for the period under review (92.3-93.7%). Among the ACTs, Artemether-lumefantrine was most prescribed. Of the 28 P. falciparum isolates evaluated, 3 (10.71%) were resistant to chloroquine with a median IC50 of 4.82μM (4.60-8.14μM), while five (17.86%) were resistant to mefloquine with a median IC50 of 25μM (10.3-41μM), 7(25.00%) to artemether with a median IC50 of 2.69μM (2.09-8.77μM), 9 (32.14%) to artesunate-mefloquine combination with a median IC50 of 9.0μM (7.98-35μM) and to artesunate, 11(39.29%) were resistant with a median IC50 of 2.4μM (1.56-5.65μM). This result shows a decline in resistance of P. falciparum to chloroquine compared to period prior to artemisinin-combination therapy as well as reduced susceptibility to artesunate and artemether. Further in vitro and in vivo monitoring will be required to inform antimalarial drug policy change.Keywords: Antimalarial, Artemisinin-combination therapy, resistance, susceptibility, microtest.