Altered systemic bioavailability and organ distribution of azathioprine in methotrexate-induced intestinal mucositis in rats

Objective: Intestinal mucositis is a significant problem haunting clinicians for decades. One of the major reasons for its occurrence is high-dose chemotherapy. The study is aimed at investigating effect of intestinal mucositis on pharmacokinetics, organ distribution, and bioavailability of azathioprine (AZA) (6-mercaptopurine). Materials and Methods: Intestinal mucositis was induced with methotrexate (MTX) (2.5 mg/kg). The oral absorption of AZA and 6-mercaptopurine (metabolite) levels were determined in control and MTX-treated rats: ex vivo (noneverted sac technique) and in vivo (pharmacokinetics and organ-distribution) using high-performance liquid chromatography. Immunohistochemistry was conducted to evaluate peptide transporter expression on luminal membrane of small intestine. Results: Intestinal permeation of AZA into systemic circulation of rats was lower after MTX administration, widely found in intestinal segments of mucositis-induced rats leading to decline in systemic bioavailability of AZA. Immunohistochemistry findings indicated diminution of peptide transporter expression representing hampered absorption of drugs absorbed via this transporter. Conclusion: Study outcome has thrown light on altered fate of AZA when administered to individuals with mucositis which suggests modified drug therapy. These findings can further be investigated in different drug classes which might be administered concomitantly in mucositis and study outcome can be further confirmed in mucositis patients in clinical practice also.