Original Development of a Controlled Release Drug Delivery System for Malaria Chemoprophylaxis Using Biodegradable Nigerian Biopolymers

Current malaria chemoprophylaxis regimens require frequent oral dosing that limits adherence, and the development of controlled release drug delivery systems that sustain therapeutic drug concentrations over extended periods would substantially improve chemoprophylaxis effectiveness for high-risk populations in Nigeria. This study developed an original controlled release drug delivery system for malaria chemoprophylaxis using biodegradable biopolymers derived from Nigerian natural sources. A formulation sciences research programme was conducted combining biopolymer extraction and characterisation, drug-polymer compatibility assessment, microsphere and implant formulation development, and in vitro-in vivo evaluation. Biopolymers characterised included chitosan extracted from Nigerian shrimp shells, poly-hydroxyl-butyrate produced by local bacterial fermentation, and Irvingia gabonensis kernel oil as a lipid matrix component. Mefloquine and proguanil were selected as model drugs due to their chemoprophylactic application. Microencapsulation by double emulsion solvent evaporation produced chitosan-mefloquine microspheres achieving 67.3 percent encapsulation efficiency and biphasic release profiles extending over 28 days in biorelevant media. Subcutaneous implant prototypes demonstrated 42-day sustained mefloquine release in Wistar rats, maintaining plasma concentrations above prophylactic threshold for the full period. Biodegradation was confirmed at 90 days with no systemic polymer toxicity signals. Comparative in vivo malaria challenge studies in P. berghei-infected mice showed 91.4 percent protection over 42 days for the implant group versus 62.1 percent for standard oral dosing. This constitutes an original contribution to controlled release drug delivery for infectious disease in Nigeria.

Keywords: controlled release, malaria chemoprophylaxis, biodegradable polymers, drug delivery system, Nigerian biopolymers