Management of adverse events in patients with metastatic renal cell carcinoma treated with sunitinib and clinical outcomes.

Patients with progressive renal cell carcinoma who undergo sunitinib treatment, experience many adverse events (AEs), including thrombopenia and hypertension. Dose reduction or treatment discontinuation due to AEs makes it difficult to control the clinical condition. Therefore, patients' understanding regarding the basics of blood pressure (BP) measurement and how to deal with each AE are particularly important. Here we report whether or not pharmacist instructions help in order to increase patients' awareness of early AE management results in an improvement of treatment outcomes. The present study included 15 patients who were administered sunitinib. From the start of sunitinib treatment, pharmacists continuously provided drug administration guidance to the patients and confirmed their awareness and knowledge regarding AEs, symptom management, and drug adherence. The relative dose intensity (RDI) of 15 patients from week 1 to 24 after sunitinib treatment was calculated. Pharmaceutical interventions significantly improved patients' understanding of BP measurements and reference values, etc. Although the RDI was 67.3%-78.7%, there were no cases of discontinuation of administration or reduction of the dose caused by e.g. hypertension, hand and foot syndrome (HFS) and stomatitis. Pharmaceutical interventions improved patients' awareness of the management of AEs and adherence to sunitinib therapy. As a result, a high RDI was maintained, which may lead to prolonged survival. Therefore, our results suggest that early AE management provided by pharmacists is particularly important to assure the safety and efficacy of sunitinib therapy.

Drug interaction between sunitinib and cimetidine and contribution of the efflux transporter ATP-binding cassette C2 to biliary excretion of sunitinib in rats.

The present study investigated the effect of the H2 antagonist cimetidine on the pharmacokinetics of a multi-targeted receptor tyrosine kinase (RTK) inhibitor, sunitinib, in Sprague-Dawley (SD) rats and Eisai hyperbilirubinemic mutant rats (EHBR) lacking the efflux transporter, ATP-binding cassette C2 protein (ABCC2). Rats received an intraperitoneal injection of cimetidine (10 mg/kg) once a day for three days. On day 4, sunitinib (3 mg/kg) was administered intravenously 30 min after the final injection of cimetidine or saline to SD rats. Disappearance of sunitinib from plasma was significantly delayed by cimetidine. The pharmacokinetic parameter of sunitinib, systemic clearance (CLSYS), was significantly reduced and the half-life was significantly prolonged, with no change in the volume of distribution at steady-state (VSS). When the effect of cimetidine on the biliary excretion of sunitinib at steady-state condition was investigated in SD rats, cimetidine had no effect on some transporter-mediated biliary excretion of sunitinib. Furthermore, the contribution of ABCC2 to the biliary excretion of sunitinib was also examined in SD rats and EHBR. The biliary clearance of sunitinib was significantly lower in EHBR, but the biliary excretion rate of EHBR was not different from that of SD rats, and the contribution of biliary excretion to systemic elimination was small, suggesting that sunitinib is mainly eliminated by cytochrome P450 3A4 (CYP3A4)-mediated metabolism and is not excreted into the bile via ABCC2. These findings indicate that co-administration of cimetidine alters the pharmacokinetics of sunitinib probably due to inhibition of CYP3A4, suggesting the possibility that cimetidine should be used carefully for patients with cancer being treated with sunitinib therapy.