An RP-HPLC Method for Quantitative Analysis of Linagliptin Entrapped in Nanotransfersomes and its Application to Skin Permeation Studies

Background: Linagliptin (LNG) is an oral hypoglycemic agent that acts by inhibiting the enzyme dipeptidyl peptidase - 4 (DPP-4) and reduces blood sugar levels in type-II diabetic patients. To date, the literature presents few analytical methods for the determination of LNG. However, no reversed phase-high performance liquid chromatography (RP-HPLC) method has been reported for the determination of LNG in nanotransfersomes and in vitro skin permeation samples. Objective: The present study involves the development and validation of RP-HPLC method to quantify LNG in both nanotransfersomes and in vitro skin permeation and deposition samples. Methods: The chromatographic analysis was performed on Luna C18 (2) column (250 x 4.6 mm, 5μm particle size) with a mobile phase consisting of a mixture of methanol: 0.2% orthophosphoric acid (50:50, v/v) at a flow rate of 1.0 mL/min, detection wavelength of 227 nm, and column temperature of 40 ^°C. Results: The method was found to be specific, linear (r² ≥ 0.999; 2-12 μg/mL), precise at both intra and inter-day levels (percentage relative standard deviation; % RSD < 2.00), accurate (percentage recovery 100.21-103.83%), and robust. The detection and quantification limits were 0.27 and 0.82 μg/mL, respectively. The mean % entrapment efficiency and the cumulative amount of LNG permeated across the rat skin from different transfersomal formulations ranged between 40.78 ± 2.54 % to 52.26 ± 2.15 % and 79.54 ± 16.67 to 200.74 ± 35.13 μg/cm² respectively. Conclusion: The method was successfully applied to determine the entrapment efficiency, in vitro skin permeation and deposition behavior of LNG-nanotransfersomes.