Drug Interaction Between Febuxostat and Thiopurine Antimetabolites: A Review of the FDA Adverse Event Reporting System and Medical Literature.

Background: There is a known drug interaction (DI) between xanthine oxidase (XO) inhibitors and the thiopurine immunosuppressants, azathioprine (AZA) and mercaptopurine (6-MP). Xanthine oxidase inhibition increases concentrations of AZA and 6-MP active metabolites, possibly resulting in myelosuppression. When allopurinol is used with AZA or 6-MP, dose reduction of AZA or 6-MP is recommended.

A Novel Pharmacokinetic Bridging Strategy to Support a Change in the Route of Administration for Biologics.

Determination of appropriate pharmacokinetic end point to bridge different dosing regimens is often a challenge when developing a new route of administration. Trough concentrations (C) are often considered the most relevant PK end point to predict efficacy (ACR20/DAS28) in the treatment of rheumatoid arthritis for biologics. However, no systematic research has been conducted to evaluate this approach.