COMPARISON OF ORAL ITASETRON WITH ORAL ONDANSETRON - RESULTS OF A DOUBLE-BLIND, ACTIVE-CONTROLLED PHASE-II STUDY IN CHEMOTHERAPY-NAIVE PATIENTS RECEIVING MODERATELY EMETOGENIC CHEMOTHERAPY

Itasetron hydrochloride is a new 5-hydroxytryptamine(3) (5-HT3) antago nist. Experimental investigations show that orally it is rapidly absor bed (about 90 min), is highly bioavailable (greater than 90%), has a l ong half-life (about 12 h) and is more potent (about 10 times) in anim al models than ondansetron, currently standard therapy for the prophyl actic control of chemotherapy induced nausea and vomiting, This paper describes the results of a study designed to assess the efficacy and t olerability of five (0.5, 1, 2, 4 and 8 mg) twice-daily doses of itase tron hydrochloride, in comparison with 8 mg b.i.d. ondansetron, Assess ments were made in patients (n = 104) with histologically confirmed ca ncer (excluding head and neck tumors) and about to receive their first course of moderately emetogenic chemotherapy. Itasetron hydrochloride demonstrated comparable efficacy to ondansetron; no statistically sig nificant between-group differences were observed in the primary (compl ete response rate) or secondary (nausea and delayed emesis) efficacy c riteria. Adverse events were similar in type and incidence across all treatment groups, and were those expected for this therapeutic class. The tolerability of itasetron hydrochloride was assessed as 'very good ' or 'rather good' by 81% of patients and 89% of physicians. In conclu sion, itasetron hydrochloride is effective and well tolerated in patie nts receiving moderately emetogenic chemotherapy. Oral doses of 1 mg b .i.d. or above will be used in further clinical studies.