Development, validation and application of LC-MS/MS method for simultaneous determination of irinotecan and cyclosporine in co-loaded self-nanoemulsifying drug delivery system.

Irinotecan (CPT-11; IRN) is used as a potent chemotherapeutic agent for CRC. Co-loaded self-nanoemulsifying drug delivery system (SNEDDS) of IRN with cyclosporine A (CSP), a P-gp inhibitor, was designed and developed. A novel liquid chromatography-triple quadrupole mass spectrometry (LC-QqQ MS/MS) method was developed and validated. The analysis was performed on a TSQ Quantis Plus triple quadrupole mass spectrometer, coupled with a Thermo Vanquish UHPLC system, using an Agilent Eclipse Plus C18 column and a gradient elution using 10mM ammonium acetate (0.1% formic acid) and methanol. Retention times were 6.2min for IRN and 10.17min for CSP. Linearity was achieved over the ranges of 10-10,000 ng/mL for IRN and 10-5,000 ng/mL for CSP, with R2 values of 0.9999 and 0.9998, respectively. Inter- and intra-day precision values were within acceptable limits, and recoveries were consistently 99-100%. The analytical method was applied for bioanalytical estimation using protein precipitation in MDCK cell permeability studies, and HCT-116 colorectal cancer cell internalization. The method demonstrates high sensitivity, reproducibility, and applicability for evaluating co-loaded SNEDDS formulations of IRN and CSP along with quantitation of IRN in MDCK and HCT-116 colorectal cell lines.