Abstract

STATISTICAL ANALYSIS OF THE POTENCY OF ANTIMALARIAL DRUGS ON MALARIA PATIENTS USING BIOASSAY METHOD

Ucheokoro Adaeze S.*, Ogoke Uchenna P.

ABSTRACT

Background: Bioassay remains a critical method for evaluating the relative potency of antimalarial drugs, particularly in resource-limited settings where pharmacokinetic studies are challenging. Establishing parallelism between dose-response curves of test and standard preparations is a fundamental prerequisite for valid potency estimation in indirect bioassays. Objective: This study assessed the potency of four generic antimalarial brands (Drugs A, B, C, D) relative to a standard formulation using clinical recovery time in 80 malaria patients. Methods: An indirect assay design was employed, measuring time (hours) to recovery after complete dosage. Parallelism was tested using three established methods: F-test, χ²-test, and equivalence testing via JMP software version 17. A 4-parameter logistic (4PL) model characterized dose-response curves. One-way ANOVA assessed variation among formulations, with bioequivalence declared when 90% confidence intervals fell within predefined limits. Results: The 4PL model demonstrated excellent fit (R² = 93.3%, AIC = 465.53). ANOVA confirmed significant variation among antimalarial drugs (p < 0.0001). However, parallelism testing failed across all methods: F-test (p = 0.0094) and χ²-test (p = 0.0001), both < 0.05. Graphical analysis revealed non-parallel dose-response curves, with inconsistent logarithmic spacing and horizontal shifts. Consequently, relative potency calculations were invalid due to violation of the parallelism assumption. Conclusion: The failure of parallelism testing prevented potency estimation, suggesting potential degradation of the reference standard or formulation inconsistencies. This underscores the critical importance of parallelism validation in bioassays and highlights the need for quality assurance of reference standards. The study recommends reviewing standard preparation protocols and conducting replicate assays with fresh reference materials to ensure reliable comparative potency assessments for antimalarial drugs.

Keywords: Bioassay, Parallelism testing, Relative potency, Antimalarial drugs, 4-Parameter logistic model, Dose-response curves.