Enhancement of In Vitro Skin Transport and In Vivo Hypoglycemic Efficacy of Glimepiride Transdermal Patches

Purpose: To utilize hydroxybutyl-β-cyclodextrin (HB-β-CD) and polyvinyl pyrrolidone (PVP) for the enhancement of the transdermal delivery of glimepiride (GMD).
Methods: Matrix-type transdermal patches containing GMD, drug coprecipitate or its inclusion complex were prepared using different gelling agents, viz, hydroxypropyl methylcellulose (HPMC), hydroxypropyl cellulose (HPC), carbopol and chitosan. In vitro skin permeation evaluation of the formulations was conducted using automated diffusion system. Selected patch formulations were assessed for hypoglycemic activity as well as for GMD plasma concentration in rats.
Results: GMD- hydroxybutyl-β-cyclodextrin (HB-β-CD) binary systems (1:2 molar ratio) enhanced GMD aqueous solubility by > 10-fold. Diffusion test showed improved release of GMD-HB-β-CD inclusion complex compared with GMD alone. Maximum cumulative amounts of GMD- HB-β-CD that permeated through rat skin was 26.97 and 14.28 μg/cm² for patches prepared with fchitosan and HPMC, respectively. Thus, GMD-chitosan patches showed significantly higher (p < 0.05) drug permeation than GMD-HPMC after 6 h. Both chitosan and HPMC patches of GMD-HB-β-CD demonstrated substantial reduction (p < 0.05) in blood glucose level (192.67 ± 21.18 and 201 ± 15.11 mg/ dl, respectively), compared with the baseline value of 240 mg/ dl.
Conclusion: Application of chitosan and HPMC transdermal patches of GMD-HB-β-CD can serve as a potential alternative to peroral GMD with improved bioavailability and patient compliance.

Keywords
Glimepiride; Transdermal patch; Coprecipitate; Inclusion complex; Hydroxypropyl methylcellulose; Polyvinyl pyrrolidone; Chitosan; Skin permeation