A study on ethosomes as mode for transdermal delivery of an antidiabetic drug

Context: A transdermal delivery system is warranted for repaglinide (RPG) which possesses half-life of 1 h and oral bioavailability of 56%. Ethosomes are useful tools for transdermal drug delivery. Objectives: To prepare and evaluate ethosomes as mode for transdermal delivery of RPG. Material and methods: Ethosomes loaded with RPG were prepared from dipalmitoyl phosphatidylcholine and ethanol by the cold method. They were characterized using Fourier transform infrared spectroscopy and differential scanning calorimetry. They were evaluated for vesicle size, entrapment efficiency and ex-vivo skin permeation. Ethosomal composition was optimized using the 3(2) factorial design. Gel containing optimzsed ethosomes was studied for antidiabetic activity in rats. Result: RPG ethosomes possessing the size of 0.171-1.727 mu m and entrapment efficiency of 75-92% were obtained. They demonstrated a significantly higher permeation (64-97% of the administered dose) across excised rat skin when compared to free drug and its hydro alcoholic solution. In-vivo, RPG ethosomal system caused sustained antidiabetic effect. Discussion: The lipid and ethanol concentration affected the physicochemical attributes and performance of ethosomes. The flexible ethosomes permeated the stratum corneum and improvized the availability of RPG for antidiabetic action. They prolonged the antidiabetic effect of RPG over a significantly longer period of time in comparison with the equivalent oral dose. Conclusion: Ethosomal system can successfully deliver RPG transdermally; sustain its effect and thus reduce its dosing frequency. Ethosomes are useful for enhancing the efficacy of RPG in the treatment of diabetes.