Formulation and Evaluation of Democlocycline Hydrochloride-Loaded Liposomal Transdermal Patch: A Factorial Design Optimization Approach

Repeated oral dosing of tetracycline antibiotics such as demeclocycline hydrochloride is associated with fluctuating plasma concentrations, gastrointestinal disturbance, and reduced patient adherence, all of which weaken the practical value of the conventional tablet form. Delivering the same drug through the skin sidesteps first-pass metabolism and dosing frequency, provided the molecule can be pushed across the stratum corneum in sufficient quantity, which is where a carrier-assisted approach becomes useful. In the present investigation, demeclocycline HCl was entrapped within phosphatidylcholine–cholesterol vesicles produced by thin-film hydration, and the resulting liposomal dispersion was cast into an HPMC K100/PVA polymer matrix to yield a transdermal patch. A 3² full factorial design (nine runs, F1–F9) was applied to examine how phosphatidylcholine (X1), cholesterol (X2) and HPMC K100 (X3) jointly govern entrapment efficiency, cumulative in-vitro release and folding endurance. Preliminary characterisation — physical description, melting-point analysis, UV scanning and solubility testing — verified the identity and pharmacopoeial-grade purity of the drug sample prior to formulation. Spectral (FTIR) and thermal (DSC) data pointed to the absence of any appreciable drug–excipient incompatibility, while SEM imaging was used to inspect surface texture. Among the nine trial batches, F7 (250 mg phosphatidylcholine : 30 mg cholesterol : 1200 mg HPMC K100) returned the most favourable combination of responses — 87.2 ± 0.4% entrapment, 91.3 ± 0.5% drug release and a folding endurance of 272 ± 3 — and was therefore taken forward for ex-vivo and microbiological testing. Permeation across excised goat skin mounted on a Franz diffusion cell produced a gradual, near-linear release curve that reached roughly 96% cumulative permeation by the tenth hour, without an early burst. Agar-well diffusion assays further confirmed that the drug retained concentration-dependent antibacterial action against E. coli and two S. aureus biotypes, while the solvent-only control produced no zone of inhibition. Collectively, the data indicate that combining liposomal entrapment with a polymeric patch matrix is a practicable route to sustained, skin-mediated delivery of demeclocycline HCl, and that the formulation is a reasonable candidate for subsequent in-vivo evaluation.