Comparative bioavailability assessment between 2 x 10 mg R-178 tablets and 2 x 10 mg 2-amino-1,7-dihydro-6H-purine-6-thione tablets administered orally in healthy participants under fasting conditions.

INTERVENTION: Single dose, crossover study design whereby each participant receives the test formulation of 2 x 10 mg 2‐amino‐1,7‐dihydro‐6H‐purine‐6‐thione extended release tablets on one occasion and the test formulation 2 x 10 mg 2‐amino‐1,7‐dihydro‐6H‐purine‐6‐thione immediate release tablets on one occasion with each dose separated by a two week washout period. The intervention for this trial is the test 2‐amino‐1,7‐dihydro‐6H‐purine‐6‐thione extended release formulation. No water is allowed for 1 hour prior to dosing until 1 hour after dosing (except for water consumed with the oral dose). Participants are required not to eat for 10 hours before receiving each dose and to fast for approximately 4 hours after receiving each dose. Bathroom visits will be supervised during the first 5 hours. Participants will be confined at the Clinical Site for 10 hours prior to dosing to ensure compliance and will be monitored for 32 hours after dosing. Standard meals will be consumed at the Clinical Site with no additional food intake allowed. Alcohol breath testing and drugs of abuse test will be performed upon each participant reporting to the Clinical Site 10 hours prior to dosing. Pre and post study laboratory tests will be completed to assess the health of participants along with HIV, Hepatitis and drugs of abuse testing. Both doses will be taken orally with 240 ml of water at ambient temperature. The 2‐amino‐1,7‐dihydro‐6H‐purine‐6‐thione tablets must be swallowed whole and a mouth check will be conducted to ensure the medication has been taken as directed. CONDITION: 2‐amino‐1,7‐dihydro‐6H‐purine‐6‐thione is indicated for the maintenance treatment of inflammatory bowel disease (Crohn's disease or ulcerative colitis).; ; 2‐amino‐1,7‐dihydro‐6H‐purine‐6‐thione is indicated for the maintenance treatment of inflammatory bowel disease (Crohn's disease or ulcerative colitis). Oral and Gastrointestinal ‐ Crohn's disease Oral and Gastrointestinal ‐ Inflammatory bowel disease PRIMARY OUTCOME: To evaluate the pharmacokinetics (as summarised by Cmax and AUC). All plasma samples will be assayed for 2‐amino‐1,7‐dihydro‐6H‐purine‐6‐thione using fully validated LC/MS/MS methods. Validation will be conducted to comply with FDA guidelines.[0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.5, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24 and 32 hours post dosing] SECONDARY OUTCOME: Time to maximum peak concentration (Tmax) will be determined by plasma sample analysis. Tmax will be the time where the maximum concentration occurred in the sample points.[0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.5, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24 and 32 hours post dosing] INCLUSION CRITERIA: Healthy Male participants. Aged between 18 and 55 Non‐smoker BMI between 18 and 30 Healthy individuals in good health as determined by medical history, physical examination, ECG, blood pressure and laboratory tests The absence of mental illness requiring medication or treatment by a physician. Able to provide written informed consent