Research into lower dosing of tofacitinib (Xeljanz®) when used in combination with cobicistat (Tybost®), a drug that reduces drug breakdow

Completed

Conditions: Rheumatoid Arthritis, Psoriatic Arthritis

Registration Number: NL-OMON26019

Lead Sponsor: Radboudumc

Brief Summary: Not available

Detailed Description: Not available

Recruitment & Eligibility

Status: Completed

Sex: Not specified

Target Recruitment: 30

Inclusion Criteria

•Rheumatoid arthritis (either 2010 ACR RA and/or 1987 RA criteria and/or clinical diagnosis of the treating rheumatologist, fulfilled at any time point between start of the disease and inclusion)
•Patients using tofacitinib for = 2 weeks in the standard dose of 5mg BID. In addition, for patients that have used tofacitinib >3 months, it is required that a good response is achieved defined as a DAS28-CRP < 2.9 or the judgement of the rheumatologist that disease activity is low.
•Patient informed consent, =16 years old and mentally competent
•Ability to measure the outcome of the study in this patient (e.g. patient availability; willing and being able to undergo repeated serum samples)
•Ability to read and communicate well in Dutch

Exclusion Criteria

•Concomitant use of inducers or potent inhibitors of CYP3A4 or moderate inhibitors of CYP3A4 and potent inhibitors of CYP2C19, or medication sensitive to changes in metabolism as a result of cobicistat co-treatment, as assessed with the KNMP G-standaard” unless an alternative is listed in Table 1.
•Known contra-indications for treatment with cobicistat in line with the summary of product characteristics.

Study & Design

Study Type: Interventional

Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Bio-equivalence of tofacitinib BID and tofacitinib + cobicistat QD, defined as the relevant steady state pharmacokinetic parameters (average concentration at steady state (Cavg,ss )/Area Under the Curve (AUC0-24), the 90% confidence interval of the geometric mean ratio falling entirely between 75% and 125%.

Secondary Outcome Measures