Dapsone

Dapsone is a synthetic sulfone with antimicrobial and anti-inflammatory activity, but conventional topical formulations may provide limited skin penetration and short local retention. This study aimed to develop, optimize, and characterize a dapsone-loaded solid lipid nanoparticle (DDP-SLN) polymeric hydrogel for controlled dermal delivery. DDP-SLNs were prepared by hot homogenization followed by probe ultrasonication using glyceryl monostearate (GMS), soya lecithin, and Tween 80. A three-factor, three-level Box–Behnken design using Design-Expert® Version 13 was employed to optimize the formulation based on particle size, entrapment efficiency, and 12-h cumulative drug release. The optimized DDP-SLN dispersion was incorporated into Carbopol 934 hydrogel and evaluated for physicochemical, rheological, drug-release, and stability characteristics. The optimized DDP-SLN showed a particle size of 140.38 nm, PDI of 0.287, zeta potential of −35.0 mV, and entrapment efficiency of 87.93%. The hydrogel exhibited homogeneous texture, pH of 6.23 ± 0.08, viscosity of 8486.67 ± 70.95 cP, and spreadability of 18.42 g·cm/s. Cumulative drug release reached 87.90% over 12 h and followed the Higuchi model (R² = 0.9910), while the Korsmeyer–Peppas exponent (n = 0.612) indicated anomalous transport. The formulation remained stable under the evaluated storage conditions, demonstrating its potential as a topical delivery system for dapsone. The system was designed to enhance drug localization while providing sustained release and hydrogel performance. These findings demonstrate the suitability of combining SLN technology with a hydrogel to improve topical dapsone delivery and maintain formulation quality.

A simple, specific, accurate and precise reverse phase high performance liquid chromatographic method is developed and validated for the estimation of Dapsone in tablet dosage form. The expected separation and peak shapes were obtained on Luna C18, 15 cm x 4.6 mm (5 μm)  column. To have an ideal separation of the drug under isocratic conditions, mixtures of solvents like methanol and water with or without different buffers indifferent combinations were tested as mobile phases on a Luna C18, 15 cm x 4.6 mm (5 μm) column. A mixture of Methanol:Water in the ratio of 40:60 v/v was proved to be the most suitable of all the combinations since the chromatographic peak obtained was better defined and resolved and almost free from tailing.  The flow rate was 1.0ml/min and effluents were monitored at 260 nm. The retention time for Dapsone was ± 2.4 min. The method was validated for accurate, precise, simple, sensitive and rapid and can be applied successfully for the estimation of Dapsone in bulk and in pharmaceutical formulations without interference and with good sensitivity. And recovery of Dapsone from tablet formulation was found to be 93%. The proposed method was successfully applied for the quantitative determination of Dapsone in tablet formulation.