A Validated HPLC Method for the Determination of Linagliptin in Rat Plasma. Application to a Pharmacokinetic Study

A sensitive and reproducible HPLC method for the determination of linagliptin (LNG) in rat plasma was developed and validated using pindolol (PIN) as the internal standard. Both LNG and PIN were separated on a Zorbax Eclipse XDB C18 column kept at ambient temperature using as mobile phase a combination of 75% methanol: 25% formic acid 0.1% pH 4.1 at a flow rate of 1.0 mL min-1. UV detection was performed at 254 nm. The method was validated in compliance with ICH guidelines and found to be linear in the range of 5-1,000 ng mL-1. The limit of quantification (LOQ) was found to be 5 ng mL-1 based on 100 µL of plasma. The variations for intra- and inter-assay precision were <10%, and the accuracy values were ranged between 93.3 and 102.5%. The extraction recovery (R%) was >83%. The assay was successfully applied to an in vivo pharmacokinetic study of LNG in rats that were administered a single oral dose of 10 mg kg-1 LNG. The maximum concentration (Cmax) and the area under the plasma concentration-time curve (AUC0-72) were 927.5 ± 23.9 and 18,285.02 ± 605.76 ng mL-1, respectively.