Evaluation of the Efficacy and Safety of Stiripentol in Patients 6 Years and Older With Primary Hyperoxaluria Type 1, 2 or 3

The target dose of stiripentol will be 50 mg/kg/day with a maximum dose of 3,000 mg/day. Patients allocated to the Stiripentol group will receive this treatment during the first 6 months, and in continuation up to 12 months.

Placebo capsules will be administered for the first 6 months. Then patients will switch to stiripentol over the 6- to 12-month period.

Collections of urine over 24 hours and the first urine in the morning (spot urines) will be carried out. Urine collections will be performed either during hospitalizations, or at home if appropriate conditions are met.

Series of blood samples will be taken (serum pregnancy test, Primary Hyperoxaluria genetic characterization, clinical laboratory assessments, vitamin B6 dosage, plasma oxalate dosage, stiripentol pharmacokinetics)

Kidney imaging will be obtained. Renal ultrasounds will be compulsory for all patients.

"Kidney Disease Quality of Life Questionnaire : KDQOL-36 for patients ≥18 years of age at screening, and the Pediatric Quality of Life Inventory (PedsQL) including the generic and KF modules (parent and/or self-report versions) for patients \<18 years of age at screening.~EQ-5D: a standardized instrument consisting of a questionnaire and a visual analog scale pertaining to 5 dimensions. Scoring of the questionnaire is based on degrees of disability. Scoring of the visual analog scale is based on a visual scale ranging from 0 (worst imaginable health state) to 100 (best imaginable health state). Higher scores indicate better health status. The EQ-5D-5L questionnaire (will be utilized in patients ≥18 years of age at screening, and the EQ-5D-Y questionnaire will be utilized in patients \<18 years of age at screening, where available."