Pharmacogenomics & Health impact of antimalarial medications in Cameroon and study the efficacy and safety of Sulfadoxine Pyrimethamine and Amodiaquine in the Northern Regions of Cameroon

Abstract

Malaria remains a real public health problem in the world despite all the efforts and the means implemented to overcome it. The poor quality and fake antimalarials, constitute an important health and economic problem.The present study aims to analyze the situation of the irrational use of antimalarials in Cameroon after a systematic review of published studies; the physico chemical analysis of Artesunate and Amodiaquine done in combination with pharmaco-technical tests, as well as the study of the effectiveness of sulfadoxine-pyrimethamine-amodiaquine (SP+AQ), versus artésunate+amodiaquine (AS+AQ), in a 2-arm, randomized, controlled study; it was also about to determine the pharmacogenomic profile (using the polymorphisms of the Cytochrome P2C8 (CYP2C8) and N-Acetyl Transferase 2 (NAT2) genes) in children aged 6 months to 10 years, with acute uncomplicated P. falciparum malaria, from the North and Far North regions of Cameroon. The DNA of Plasmodium falciparum was extracted by the Chelex method. The merozoite surface protein 2 (msp2) gene was amplified in the confirmed treatment failure cases, in order to differentiate between recrudescence and re-infection. Molecular markers for Sulfadoxine+Pyrimethamine drug resistance used, were genetic polymorphisms in the dihydrofolate réductase (dhfr) gene. Genotyping was done by polymerase chain reaction – restriction fragment length polymorphism (PCR-RFLP); the portions containing the C59R and S108N polymorphisms of the dhfr gene, the CYP2C8 gene, and the NAT2 gene were amplified by PCR, followed by enzymatic digestion with specific enzymes (XmnI+BsrI); BclI and (BamH1+Kpn1+Taq1) respectively. Finally, software STRING and MEGA were used to determine protein-protein interactions from the N Acetyl transferase 2 (NAT2) protein and the others. All the 15 batches of (AS+AQ) screened were under-dosed, non-compliant, largely imported from India and found mainly in hospitals and health centers. A total of 235 children, treated for the trial with (AS+AQ)) and (SP+AQ) were followed up for 28 days to assess the response to treatment. Early treatment failure (ETF) cases recorded were 24 (20.5%) in the AS+AQ group and 21(17.8%) in the SP+AQ group. Adequate clinical and parasitological response (ACPR) cases observed on day 14 were 99 (84.6%) in the AS+AQ group and 91 (77.1%) in the SP+AQ group. ACPR cases observed on day 28 were 61 (71.8%) in the AS+AQ group and 59 (7 3.75%) in the SP+AQ group. The cure rates were respectively at 91.8% and 91.4% in the AS+AQ and in SP+AQ. However, recrudescence was observed in 7 cases, with respectively 3 and 4cases in the AS+AQ and in the SP+AQ group. After digestion of the dhfr gene in recrudescence cases, the C59R mutation was observed in all, while the S108N mutation was observed in 5 ones. The pharmagenomy profile allowed to identify, two alleles: CYP2C8*1 (76%) and CYP2C8*2; we found 70% fast metabolizers phenotypes for the CYP2C8 gene. The NAT2*6 allele was higher (39%) than the NAT2*5/6 genotype (28.12%). After treatment, 63.5% presented an adequate clinical and parasitological response (ACPR) and 24% an early treatment failure (ETF). In the regions of North Cameroon, the wild CYP2C8 allele and the associated rapid metabolizers, as well as the NAT2*5/6 genotype were more present; the fast phenotype was much more susceptible to experience early treatment failures and much more vulnerable to experience late parasitological failures.