Topical delivery of meropenem via spanlastic carbopol gel: in-vitro studies and in-vivo application in pressure ulcers

The optimized formulation (Batch F5), composed of Span 60 and Brij 35 in a 1:4 M ratio, exhibited a particle size of 462 nm, spherical morphology, 69.5% drug encapsulation efficiency, and 20% drug release within 6 h. The gel form of the same batch showed a comparable release profile. Antibacterial testing revealed that MRP-SP reduced the minimum inhibitory concentration by 2.4-fold against Pseudomonas aeruginosa compared to free MRP. Additionally, MRP-SP significantly downregulated the expression of mexA, a key resistance gene. <i>In vivo</i>, the topical application of MRP-SP demonstrated superior therapeutic activity in treating ulcerative skin lesions in non-diabetic mice, as evidenced by wound closure percent (89% at 10 days), wound area (49% at 10 days), and histopathological improvements. Overall, the meropenem-loaded spanlastic formulation shows strong potential as an effective topical therapy for bacterial skin infections.