A Liquid Chromatography Coupled to Tandem Mass Spectrometry Method for Simultaneous Estimation of Saxagliptin and Avanafil: Application to Pharmacokinetic Drug-Drug Interaction in Type 2 Diabetic Rat Model

Erectile dysfunction is a common complication of type 2 diabetes. The combination of saxagliptin and avanafil can effectively manage both conditions in individuals with type 2 diabetes. However, evaluating the potential pharmacokinetic interactions for co-administration of saxagliptin and avanafil is crucial. Here, we developed a sensitive bioanalytical method for simultaneously quantifying saxagliptin and avanafil in rat plasma using liquid chromatography hyphenated to triple quadrupole mass spectrometry. The chromatographic separation of saxagliptin, avanafil, and irbesartan (internal standard) was achieved on an Aquity BEH C18 column (100 x 2.1 mm, 1.7 mu m), using 0.1% formic acid in water and acetonitrile as mobile phase with the gradient elution at a flow rate of 0.2 mL/min. Mass detection was carried out using selective reaction monitoring mode, with the product ions for saxagliptin, avanafil, and irbesartan being 180.2, 375.1, and 207.1 m/z, respectively. The developed liquid chromatography coupled to tandem mass spectrometry method was validated as per the US Food and Drug Administration guidelines in rat plasma. The validation findings confirmed the method's robustness and suitability for accurate quantification of saxagliptin and avanafil in rat plasma with the limit of quantification of 1 ng/mL for both the drugs and were linear in the range of 1-2000 ng/mL. The study found no significant pharmacokinetic interaction between saxagliptin and avanafil, suggesting they can be safely co-administered to patients with type 2 diabetes.