The influence of storage time on ponazuril concentrations in feline plasma

Background The pharmacokinetics of ponazuril have been determined in several species; however, there is very little information on the stability of the drug after storage for long periods of time. This study was undertaken to determine the stability of ponazuril in plasma samples stored at −80 °C, which is the temperature most commonly used in the author’s laboratory. Method Spiked plasma samples (0.3, 7.5, and 15 µg/mL) were stored at −80 °C for three months. Analysis occurred on the first day and then once a week for the following twelve weeks. The drug was extracted using a chloroform extraction and separated by high performance liquid chromatography using ultraviolet detection. Results There was no loss of drug for any concentration for the first four weeks of storage. There was an average loss of less than 5% from day 35 through day 70 and an average loss of 6% on day 77 and 84. The data suggest that ponazuril is stable for 4 weeks when stored at −80 °C and undergoes minimal loss in the remaining 8 weeks.

Development and validation of Stability-indicating RP-UPLC Method for the Simultaneous Determination of Ivacaftor, Tezacaftor and Elexacaftor in bulk and their Formulation

A simple reproducible stability indicating RP-UPLC method was developed for the simultaneous determination of Ivacaftor, Tezacaftor and Elexacaftor in their combined dosage forms using HSS C18, 1.8μm, 100mm x2.1 mm i.d. column. A mobile phase of phosphate buffer (10mM) pH-4.8 and acetonitrile in the ratio of 70: 30v/v mixture was used for separation and quantification of ivacaftor, tezacaftor and elexacaftor. The present drug analytes were run at a flow-rate of 0.3ml/ min at 30°C temperature. The injection volume was 2μL and with ultraviolet detection at 270nm. Under these conditions, elexacaftor, ivacaftor and tezacaftor were eluted at 0.72min, 1.4min and 1.9min respectively with a total run time shorter than 5min. The developed method was validated according to International Conference on Harmonization (ICH) guidelines. The developed RP-UPLC method was applied successfully for quality control assay of Ivacaftor, Tezacaftor and Elexacaftor in their combination drug product.