DEVELOPMENT AND VALIDATION OF UV SPECTROPHOTOMETRIC METHOD AND FORMULATION & EVALUATION OF QUININE SULPHATE NANOEMULGEL

Background and Objectives: Quinine sulphate is a classical cinchona alkaloid with potent antimalarial and skeletal muscle-relaxant activity. Its clinical utility is constrained by poor aqueous solubility, a short biological half-life (8–14 h), and significant gastrointestinal side effects. The present study aimed to: (i) develop and validate a simple UV spectrophotometric analytical method for quinine sulphate in 0.1 N HCl following ICH Q2(R1) guidelines and (ii) prepare and comprehensively evaluate a topical nanoemulgel formulation using oleic acid, Tween 80, propylene glycol and Carbopol 934. Methods: A UV spectrophotometric method was developed at λmax 347 nm in 0.1 N HCl and validated for linearity, precision, accuracy, LOD, LOQ, specificity and robustness. Pseudo-ternary phase diagrams guided the selection of Smix ratios. Three nanoemulgel formulations (F1: Smix 1:1; F2: Smix 2:1; F3: Smix 3:1) were prepared by spontaneous emulsification followed by ultrasonication, and incorporated into a 0.5% Carbopol 934 gel base. Formulations were evaluated for globule size, PDI, zeta potential, pH, viscosity, spreadability, drug content and in vitro drug release via Franz diffusion cell. Results: The UV method showed excellent linearity (r² = 0.9998, range 2–14 µg/mL), intraday and interday %RSD <2%, and accuracy (99.63–100.31%). LOD and LOQ were 0.48 and 1.45 µg/mL respectively. Formulation F2 demonstrated optimal parameters: globule size 98.7 ± 2.8 nm, PDI 0.186 ± 0.008, zeta potential –26.2 ± 1.1 mV, drug content 99.18 ± 0.45%, and highest cumulative drug release of 93.7% over 12 h following Higuchi diffusion kinetics. Conclusion: The validated UV spectrophotometric method is suitable for routine quality control. Formulation F2 emerged as the optimized batch, confirming that quinine sulphate nanoemulgel is a promising alternative delivery platform offering improved solubility, controlled release and enhanced patient compliance.