Purpose: To explore the pharmacokinetics (PKs) of paclitaxel and two major metabolites after three single oral administrations of a novel drinking solution and two capsule formulations in combination with cyclosporin A (CsA) in patients with advanced cancer. Moreover, the tolerability and safety of the formulations was studied. In addition, single nucleotide polymorphisms in the multidrug resistance (MDR1) gene were determined.
Patients and methods: Ten patients were enrolled and randomized to receive CsA 10 mg/kg followed by oral paclitaxel 180 mg given as (1) drinking solution (formulation 1), (2) capsule formulation 2B, and (3) capsule formulation 2C on day 1, 8, or 15.
Results: The median C (max) of paclitaxel was 0.42 (0.23-0.96), 0.48 (0.08-0.59), and 0.39 (0.11-1.03) microg/ml and the area under the plasma concentration-time curve was 2.83 (1.69-5.12), 2.01 (1.57-3.04), and 2.67 (1.05-3.61) mug h/ml following administration of formulations 1, 2B, and 2C, respectively. The novel formulations were tolerated after single oral dose without causing relevant gastrointestinal or haematological toxicity.
Conclusions: The PK and metabolism of paclitaxel were comparable between the oral formulations co-administered with CsA.