Transdermal nortriptyline hydrocloride patch formulated within a chitosan matrix intended to be used for smoking cessation.

OBJECTIVE: The aim of this study was to prepare and characterize both physically and biopharmaceutically, a nortriptyline hydrochloride (NTP-HCl) patch formulated in chitosan. METHODS: 16 g of each chitosan patch formulation (I, II and III, see Table 1 ) was poured onto rectangular glass plates (64 cm²) at a height of 1 mm and dried for 24 h at room temperature. In order to characterize the chitosan patches, polarized microscopy, in vitro skin permeation studies by passive diffusion and iontophoresis and rheological and bioadhesion studies were performed. RESULTS: Polarized microscopy revealed the absence of aggregates and crystal forms of NTP-HCl in all transdermal patches after 30 days of storage. The rheological behavior of Patches I, II and III was predominantly elastic. The low level of adhesion of Patch III (containing PF-127 + 1-dodecanol) could be a result of the interactions between chitosan and PF-127 in the presence of 1-dodecanol. Patches I and II had approximately the same value of adhesion (≈ 60 mN.mm). The transdermal patch with chitosan, PF-127 and 1-dodecanol (Patch III) provided a reasonable flux of NTP-HCl across the skin compared with Patches I and II. Iontophoresis applied to the patches did not increase the penetration of NTP-HCl across the skin. CONCLUSIONS: The data suggest that Patch III is suitable for use in clinical practice pending further studies.

Enhancement of nortriptyline penetration through human epidermis: influence of chemical enhancers and iontophoresis.

Different known percutaneous chemical enhancers and iontophoresis have been tested in-vitro to study their ability to increase transdermal absorption of nortriptyline hydrochloride (20 mg mL(-1)). The chemicals 1-dodecanol, Span 20, Azone, (R)-(+)-limonene or isopropyl myristate were used as an overnight pretreatment at 5% (w/w) in ethanol. Furthermore, isopropyl myristate (20%, w/w) and propylene glycol (15%, w/w) were tested in the same vehicle. Iontophoresis was applied directly to the nortriptyline hydrochloride donor solution for three different concentrations (20, 2 and 0.5 mgmL(-1)). The chemical enhancers slightly increased the nortriptyline transdermal flux but iontophoresis was more efficient. In this case, nortriptyline transdermal flux was concentration dependent, having a higher flux when the concentration was lowered. Therefore, iontophoresis was the most suitable technique to increase transdermal absorption of nortriptyline and it could be an alternative method to provide therapeutic concentrations of this drug in smoking cessation treatment.