Formulation and characterization of alprazolam transdermal gel based on nanoliposomes

Background: Nowadays transdermal drug delivery systems (TDDS), as an appropriate replacement for oral and parenteral dosage forms, are developing. These systems which designed to transport drugs through skin layers into the systemic circulation, have several benefits such as avoiding first-pass metabolism, sustained and controlled drug release, reducing side effects, and ease of use. The aim of this study was to formulate alprazolam transdermal gel, as a short-acting anxiolytic of benzodiazepines class, based on the nanoliposomes. Materials and methods: At the first, different amounts of phospholipid, and cholesterol were used to produce alprazolam-loaded nanoliposomes through solvent injection method. Vesicle size and encapsulation efficiency tests were performed on the samples and statistical models based on response surface methodology (RSM) were developed to find the optimal formulation. Optimal liposomal structure after morphological characterization was used to produce alprazolam 0.5 mg/g transdermal gel. Three formulated gels with different content of carbomer were examined for viscosity, stability and in vitro skin permeation. Results: The optimal formulation of the liposomal structure included 10 mg/mL of phospholipid and 10% w/w cholesterol, resulted in the production of nanoliposomes with a size of 115 nm and an encapsulation efficiency of 91%. As the carbomer content in the gel increased, the rate of drug permeation into the skin was decreased. Conclusion: Alprazolam transdermal gel was successfully formulated in this research with acceptable skin permeation, good stability and appropriate physicochemical characteristics.