Formulation, characterization, and toxicological evaluation of quinestrol-loaded nanoparticles for extended oral contraceptive efficacy in rodent pest management

Fertility control of rodents offers a promising alternative strategy, providing a long-term solution by gradually reducing the rodent population through controlled reproduction. Quinestrol, a synthetic estrogen, can potentially mitigate rodent fertility, but its lower bioavailability in the body limits its effectiveness. In this study, we prepared polymeric nanoparticles using standard polymer-based encapsulation techniques. This study aims to formulate, characterize, and evaluate quinestrol-based poly (lactic-co-glycolic acid) (PLGA) nanoparticles to enhance the bioavailability and contraceptive efficacy of quinestrol in rodents over extended periods. Blank PLGA nanoparticles (PNP) and those loaded with quinestrol (QNP) were successfully formulated using the emulsion-evaporation method and characterized for size, zeta potential, release kinetics and stability. The study further evaluated the toxicological impact of these nanoparticles on reproductive hormones in female rats (<i>Bandicota bengalensis</i>), measured using ELISA, and administered orally through cereal-based ready-to-use baits containing bulk quinestrol (QB-B) and QNP (QNP-B). Successful encapsulation yielded QNP (337.93 ± 6.51 nm), smaller than PNP (354.33 ± 3.87 nm), with a 13.42% drug loading. Low PDI (<0.3) confirmed uniform size. Drug release involved an initial burst followed by slow release up to 96 h. Quinestrol in both QNP-B (10 ppm) and QB-B (100 ppm) increased estradiol (11.59 to 32.38-41.13 pg/mL) and progesterone (4.70 to 14.42-18.25 ng/mL), while reducing FSH (0.94 to 0.42-0.45 mIU/mL) and LH (28.15 to 17.60-18.69 mIU/mL) after 15 days. QNP-B effects lasted 75 days, compared to 45 days for QB-B, demonstrating the prolonged efficacy of QNP and supporting PLGA-based delivery as a promising approach for sustained rodent fertility control.