Development, validation and application of a UPLC-MS/MS method for simultaneous quantification of OPC-61815 and its metabolites tolvaptan, DM-4103 and DM-4107 in human plasma.

OPC-61815 is an intravenous formulation vasopressin antagonist designed to treat heart failure patients, especially who have difficulty in oral intake. Tolvaptan together with DM-4103 and DM-4107 are considered as the major metabolites of OPC-61815 biotransformed in the liver via cytochrome P450 (CYP) 3A. An efficient and robust ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantification of OPC-61815 and its three metabolites in human plasma was developed and fully validated. To our best knowledge, it was the first published method that simultaneously quantified all of these four analytes in only one run. Simple and rapid sample preparation procedure and very short UPLC-MS/MS run time (3.5 min) offered OPC-61815 and its metabolites relatively high throughput detection, which was greatly beneficial to further clinical bio-sample analysis. The method showed good linearity and sufficient sensitivity in the range of 2.00-1000 ng/mL with a low limit of quantitation (2.00 ng/mL) for each analyte. For samples with concentrations above 1000 ng/mL, 100-fold dilution with blank plasma before sample preparation was accepted. High precision and accuracy, high selectivity and satisfactory recovery of this method were demonstrated. For all of the four analytes, no significant matrix effect or carry-over was observed. The stability of analytes and internal standards under different conditions were evaluated to ensure they were stable during the whole period of storage, preparation and detection. Also, re-injection reproducibility was investigated. In addition, the conversion test showed that almost no OPC-61815 converted into DM-4103 and DM-4107 during sample processing, while attention should be paid to the concentration difference between OPC-61815 and tolvaptan in bioanalysis. The developed UPLC-MS/MS method was successfully applied to an open, single and multiple dose administration phase I trial for monitoring the pharmacokinetics of OPC-61815. This work provided a promising way for further pharmacokinetic study of OPC-61815.

Efficacy and safety of intravenous OPC-61815 compared with oral tolvaptan in patients with congestive heart failure.

AIMS: This multicentre, randomized, controlled, double-blind, parallel-group Phase III study was conducted to confirm the non-inferiority of OPC-61815 (tolvaptan sodium phosphate) intravenous injections to oral tolvaptan tablets in patients with congestive heart failure and volume overload despite receiving diuretics other than vasopressin antagonists. METHODS AND RESULTS: Congestive heart failure patients with volume overload despite receiving diuretics other than vasopressin antagonists were randomly assigned (1:1) to receive OPC-61815 (16-mg injection; n = 149) or oral tolvaptan (15-mg tablet; n = 145) once daily for 5 days. Most patients were male; the mean age and weight were 74.7 years and 62.1 kg, respectively; other demographic and clinical characteristics were similar between groups. In this study, the primary endpoint was the change in body weight from baseline to the day after the last dose. Secondary endpoints included improvement from baseline in congestive findings and New York Heart Association classification. The change in body weight was -1.67 kg [95% confidence interval (CI): -1.93, -1.41] and -1.36 kg (95% CI: -1.62, -1.10) in the OPC-61815 group and tolvaptan group, respectively; the difference in the least squares mean between the groups was -0.31 kg (95% CI: -0.68, 0.06). Given the upper CI did not exceed the pre-specified limit of 0.48, this confirmed the non-inferiority of injectable OPC-61815 to oral tolvaptan. Daily urine volume and daily fluid intake increased, and daily fluid balance was negative throughout the treatment period; changes were similar for both groups. All evaluated congestive symptoms and New York Heart Association classifications showed improvement and safety findings were similar between the groups. The incidence of hyperkalaemia was higher in the OPC-61815 group, and the incidence of thirst and dry mouth was higher in the tolvaptan group. Most treatment-emergent adverse events were mild to moderate; one serious treatment-emergent adverse event of hyperkalaemia in the OPC-61815 group was considered treatment related. CONCLUSIONS: OPC-61815 (16-mg injection) was confirmed as non-inferior to oral tolvaptan (15-mg tablet) in patients with congestive heart failure and inadequate response to diuretics; no new safety concerns were observed.

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.