Pharmacokinetics, Pharmacodynamics, Efficacy, and Safety of OPC-61815, a Prodrug of Tolvaptan for Intravenous Administration, in Patients With Congestive Heart Failure-A Phase II, Multicenter, Double-Blind, Randomized, Active-Controlled Trial

Background: Tolvaptan is an orally administered aquaretic drug indicated for patients with congestive heart failure (CHF) to remove excess fluid. OPC-61815, a prodrug of tolvaptan with improved water solubility, is considered suitable for intravenous (IV) administration. This Phase II study investigated the OPC-61815 dose that would result in an exposure equivalent to tolvaptan 15 mg. Methods and Results: We conducted a multicenter, randomized study in Japanese patients aged 20-85 years with CHF and volume overload despite treatment with diuretics other than vasopressin antagonists. Patients received IV OPC-61815 2 mg (n=13), 4 mg (n=12), 8 mg (n=12), 16 mg (n=11), or oral tolvaptan 15 mg (n=12). The primary endpoint was tolvaptan exposure on treatment Day 1; efficacy and safety were also assessed. Tolvaptan exposure increased in a dose-dependent manner following a single IV administration of OPC-61815; the exposure following an IV dose of OPC-61815 16 mg was similar to that of a tolvaptan 15-mg tablet, with no marked differences in safety or tolerability. OPC-61815 increased urine volume from baseline, resulting in decreased body weight and improved lower limb edema. No notable safety concerns were observed. Conclusions: In this first study of OPC-61815 in patients with CHF, exposure following a single IV administration of OPC-61815 16 mg was comparable with a single oral administration of tolvaptan 15 mg, with no safety concerns.