A single center, single dose, open-label, randomized, two period crossover study to assess the bioequivalence of an oral azathioprine suspension 10 mg/mL (Jayempi™) versus oral azathioprine tablet 50mg (Imurek®, Aspen Pharma Trading Limited, Dublin, Ireland.) in at least 30 healthy adult subjects under fasting conditions.

This will be a single-dose, open-label, randomised, two-period crossover study with orally administered 1 x 5mL (50 mg) of Jayempi™ Oral Suspension 10mg/mL versus oral azathioprine tablet 50mg (Imurek®, Aspen Pharma Trading Limited, Dublin, Ireland) on two separate occasions conducted under fasting conditions in healthy male and female subjects at a single study centre.

The study will comprise:

• Thiopurine methyltransferase (TPMT) testing;
• Screening period of maximum 28 days
• Two treatment periods (each of which will include a PK profile period of 12 hours) separated by a wash-out period of at least 3 calendar days (minimum number of days based on half-life of the analyte) and maximum of 14 calendar days between consecutive administrations of the IMP
• A post-study visit 7-10 days after the last dose of the last treatment period of the study.

Subjects will be randomly assigned to treatment sequence, prior to the first administration of IMP.

Inclusion Criteria:

• Healthy Volunteers.
• No significant medical history or conditions that may interfere with the study.
• Adequate contraception.

Exclusion Criteria:

• Volunteers who may be likely to have the inherited mutated NUDT15.
• Subjects with a deficient, low or intermediate TPMT enzyme activity.
• Disease that may interfere with the safety of the participant or the study outcome measures.
• Participants who want to procreate in the next 6 months.

AEs were collected up to the end of the follow-up period (up to 10 days after Treatment period 2) and over a total period of 2 months.