Therapeutic equivalence of single oral doses of dolasetron mesilate and multiple doses of ondansetron for the prevention of emesis after moderately emetogenic chemotherapy. European Dolasetron Comparative Study Group.

This multicentre, randomised, double-blind study was designed to compare the anti-emetic efficacy and safety of single oral doses of dolasetron mesilate with that of the approved oral, multiple-dose regimen of ondansetron in 399 cancer patients receiving moderately emetogenic chemotherapy. Single oral doses of 25, 50, 100 or 200 mg of dolasetron mesilate were administered 1 h prior to the initiation of moderately emetogenic chemotherapy. Multiple doses of ondansetron (8 mg x 3 or 8 mg x 4) capsules, or matching placebo for patients randomised to dolasetron, were given 1.5 h before and 6.5, 14.5 and 22.5 h after the start of chemotherapy (total dose = 32 mg). Efficacy was evaluated for 24 h after the initiation of chemotherapy. The most frequently used moderately emetogenic chemotherapeutic agents included cyclophosphamide, doxorubicin and carboplatin (28.4, 23.1 and 20.6\% of patients, respectively). A statistically significant (P < 0.001) linear dose-response relationship was observed over the entire dolasetron dosage range for all efficacy parameters. Complete response rates were 45.0, 49.4, 60.5 and 76.3\% for 25, 50, 100 and 200 mg dolasetron mesilate, respectively, and 72.3\% of ondansetron patients. A single oral 200 mg dolasetron mesilate dose was therapeutically equivalent to ondansetron for all efficacy parameters and patient satisfaction was high. Overall, there were no significant differences in the incidence of adverse events between any of the dolasetron mesilate doses, or between dolasetron and ondansetron. Headache was most frequently reported (approximately 15\% for each drug). No clinically important changes in vital signs or clinical laboratory parameters were observed with either drug. In conclusion, a single oral 200 mg dolasetron mesilate dose was therapeutically equivalent to multiple-dose ondansetron in the prevention of emesis and nausea following moderately emetogenic chemotherapy.