Bio analytical method for the combination of Lipid lowering and Anti hypertensive agents

Abstract

Even though the synergistic vascular protective effect of statins and angiotensin receptor blockers is quite known, the pharmacokinetic interaction among these two classes is yet to be understood facilitating the necessity of developing analytical methods for their determination. Herein, a bio-analytical method using RP-HPLC/UV was developed and fully validated for simultaneous estimation of rosuvastatin and candesartan in human as well as rat plasma using atorvastatin as an internal standard. Solid-phase extraction was used for sample clean-up and its subsequent optimisation was carried out to achieve higher extraction efficiency and to eliminate matrix effect. A quality by design approach was used, wherein three-level factorial design was applied for optimisation of mobile phase composition and for assessing the effect of pH of the mobile phase using Design Expert Software. Adequate separation for both analytes was achieved with Waters C18 column (250 × 4.6 mm, 5 μm) using ACN: 5 mM Sodium acetate buffer (70:30, v/v; pH adjusted to 3.5 with acetic acid) as a mobile phase at a flow rate of 1.0 ml/min and wavelength of 254 nm. The method when validated as per US-FDA guidelines was found to be precise as well as accurate. Extraction recovery observed for both analytes was above 85% as well as reproducible and consistent. Stability studies showed the samples to be stable over a long period covering from sample collection to final analysis. The validated method was successfully applied to Pharmacokinetic study in Wistar rats and the data did not reveal any evidence for a potential drug-drug interaction between ROS and CAN. This information provides evidence for clinical rational use of ROS and CAN. Similarly, a novel bio-analytical method using RP-HPLC/UV method was developed and fully validated for simultaneous estimation of pitavastatin and candesartan in human as well as rat plasma using telmisartan as an internal standard. The two analytes were extracted from plasma sample using liquid-liquid extraction and then separated on a Waters Reliant C18 column (4.6 × 250 mm, 5 μm) using ACN: 5 mM Sodium acetate buffer (80:20, v/v; pH adjusted to 3.5 with acetic acid) as a mobile phase at a flow rate of 0.8 ml/min and wavelength of 234 nm. The developed method is validated in terms of selectivity, recovery, accuracy, precision, matrix effect, dilution integrity and stability studies as per US-FDA guidelines. The method was successfully applied to investigate pharmacokinetic interaction between PIT and CAN in wistar rats. The mean plasma concentration-time curves of PIT and CAN showed that single PIT as well as CAN show similar pharmacokinetic properties to those obtained when co-administrated with each other (P value > 0.05). Hence, there is no iv evidence for a potential drug-drug interaction between PIT and CAN. This information provides evidence for clinical rational use of CAN and PIT in cardiovascular patients. The application of the method reported here is the first to study the pharmacokinetic interaction of PIT and CAN in rat plasma after a single oral dose. Their individual pharmacokinetic properties were unaffected by co-administration providing the evidence for their clinical rational use. The developed HPLC method is mass compatible and can also be used in a LC-MS/MS assay. The present study provides a valuable tool for studying drug-drug interaction amongst statins and sartans; hence can be further useful for their therapeutic drug monitoring as well as clinical pharmacokinetic studies.