Development, physicochemical characterization, and larvicidal efficacy of a novel Plectranthus barbatus Andrews solid formulation against Aedes aegypti L

The increasing burden of Aedes aegypti -transmitted arboviruses highlights the need for innovative vector control strategies capable of overcoming the stability and dissolution limitations of botanical biolarvicides. However, the development and ecotoxicological evaluation of tablet-based formulations designed to improve the practical characteristics of botanical larvicides remain poorly explored. This study reports the development and ecotoxicological evaluation of a patented tablet formulation incorporating Plectranthus barbatus leaf extract. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) demonstrated delayed thermal decomposition of the botanical matrix. Compatibility assessments by DSC and Fourier-transform infrared (FTIR) spectroscopy confirmed the absence of incompatibilities between the extract and selected excipients. The tablets exhibited rapid disintegration, with complete breakdown within 3 min 3 s under dynamic and 8.00 min under static conditions. In larvicidal bioassays against third-instar Ae. aegypti larvae, a single-dose tablet containing 0.48% (w/v) extract caused 40.0% mortality at 24 h and 66.2% at 48 h. Concentration–response modeling yielded an LC 50 of 0.309% (w/v), lower than that of the crude extract (LC 50 = 0.48%), with a diagnostic concentration of 0.34% (w/v). Ecotoxicological assays revealed acute sensitivity in Artemia salina (LC 50 = 0.31% w/v at 24 h) and Tisbe biminiensis (LC 50 = 0.65% w/v at 72 h). Additionally, 0.30% significantly delayed T. biminiensis development. Overall, the formulation retained larvicidal activity of P. barbatus and exhibited favorable thermal and disintegration characteristics under laboratory conditions. Further studies on storage stability, ecotoxicological effects, and semi-field or field performance are required before practical application.