Bioavailability Study of Stiripentol After Single Oral Administration of Two Different Formulations (Capsule and Oral Suspension) in 24 Healthy Subjects

This is a Phase I, open-label, randomized, single-center, two-way cross-over study evaluating the relative bioavailability, pharmacokinetics, safety, and palatability of two formulations of stiripentol (Diacomit®), indicated in Dravet syndrome. The investigational products are 500 mg capsules (reference) and a 50 mg/mL oral suspension (test).

The primary objective is to compare the relative bioavailability of the two formulations after a single 1,000 mg oral dose under fed conditions, based on Cmax, AUC0-t, and AUC0-∞. Secondary objectives include other PK parameters (tmax, tlag, ke, t1/2) and characterization of metabolites MIa and MIb. Palatability of the suspension will be assessed by questionnaire.

Safety evaluation will include adverse events, laboratory tests, ECGs, urinalysis, drug and alcohol screening, serology, and vital signs.

Twenty-four healthy volunteers (18-50 years) will be enrolled. Eligibility: BMI 18-30 kg/m², weight ≥50 kg, normal ECG and labs, and informed consent. Women of childbearing potential must use effective contraception and test negative for pregnancy. Exclusions: significant disease, recent surgery or blood donation, hypersensitivity, difficulty swallowing, use of CYP modulators (e.g., carbamazepine, grapefruit, herbal products), drug or alcohol abuse, smoking >5 cigarettes/day, or inability to follow dietary restrictions. Subjects testing positive for HIV, HBV, HCV, or drugs of abuse will also be excluded.

Each participant will attend a screening visit within 28 days before dosing, then two 3-day hospitalizations separated by a 7-15-day washout. On Day 1 of each period, they will receive either two capsules (1,000 mg) or 20 mL suspension (1,000 mg). Blood will be collected at 36 timepoints (≈180 mL total) for PK assessment.

The total study duration per subject is about seven weeks, including screening, hospitalization, dosing, washout, and follow-up. Treatment consists of one dosing day per period.

Sample size was based on prior data: 21 pairs provide 80% power for bioequivalence within 0.80-1.25 bounds; 24 subjects will be recruited to account for dropouts. Analyses will include the Safety Set, PK Concentrations Set, and PK Analysis Set.

This trial aims to establish whether the oral suspension provides a PK profile comparable to capsules, while generating safety, tolerability, and palatability data to support a more convenient formulation for Dravet syndrome patients.