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 forevaluating the relative potency of antimalarial drugs,particularly in resource-limited settings where pharmacokineticstudies are challenging. Establishing parallelism between dose-Department of Pharmaceutics and Pharmaceutical Technology,University of Port Harcourt, Port Harcourt 500004, Nigeria.response curves of test and standard preparations is afundamental prerequisite for valid potency estimation inindirect bioassays.Objective: This study assessed the potency of four genericantimalarial brands (Drugs A, B, C, D) relative to a standardformulation using clinical recovery time in 80 malaria patients.Methods: An indirect assay design was employed, measuringtime (hours) to recovery after complete dosage. Parallelism wastested using three established methods: F-test, χ²-test, andequivalence testing via JMP software version 17. A 4-parameter logistic (4PL) model characterized dose-response curves. One-way ANOVAassessed variation among formulations, with bioequivalence declared when 90% confidenceintervals fell within predefined limits.Results: The 4PL model demonstrated excellent fit (R² = 93.3%, AIC = 465.53). ANOVAconfirmed significant variation among antimalarial drugs (p < 0.0001). However, parallelismtesting 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.