A Randomized Trial of Modified-Release Versus Immediate-Release Tolvaptan in ADPKD.

Introduction: Tolvaptan, for treatment of autosomal dominant polycystic kidney disease (ADPKD), is provided as immediate-release (IR) tablets administered twice daily in split-dose regimens to suppress urine osmolality to <300 mOsm/kg. A modified-release (MR) formulation was developed for once-daily (QD) dosing to increase compliance and mitigate urinary symptom burden. This phase 2, dose-ranging study (NCT01210560) compared pharmacokinetics, pharmacodynamics, and tolerability of several MR regimens with IR in patients with ADPKD.

Methods: This was a multicenter, parallel-arm, randomized, crossover, double-blind, placebo-controlled trial. Each of 2 study arms had 12 subjects and 3 crossover periods. Dose regimens were administered for 7 days; placebo-masked QD versus split-dose treatments. Endpoints included pharmacokinetic parameters, percentage of subjects with urine osmolality <300 mOsm/kg, urine volume, number of daily urine voids, and tolerability.

Results: Tolvaptan MR 20 to 120 mg exhibited dose-proportional pharmacokinetics. Percentage of subjects with spot urine osmolality <300 mOsm/kg increased with dose, with tolvaptan MR 120 mg and IR 90+30 mg each suppressing 91.7% of subjects below this level. Urinary burden on the ADPKD Nocturia Quality of Life, ADPKD Urinary Urgency, and ADPKD Urinary Frequency Questionnaires correlated with tolvaptan exposure, with high interindividual variability in responses. Changes in questionnaire scores were sensitive to changes in urine volume but not proportional to volume change, reflecting differences in subject tolerance to increased urine volume.

Conclusion: Tolvaptan MR exhibited predictable and dose-proportional pharmacokinetics and no improvement in tolerability versus tolvaptan IR. Tolerability of the urinary effects of treatment within the high-dose MR and IR groups exhibited substantial interindividual variability.