IMPACT OF DRUG-DOSAGE AND BRAND ON BIOAVAILABILITY AND EFFICACY OF PRAZIQUANTEL

The efficacy of two brands (brand 1=Biltricide; Bayer AG, Leverkusen, Germany; brand 2= Distocide; EPICO pharmaceuticals, Cairo, Egypt) of p raziquantel (PZQ) in full and half doses (40 and 20 mg kg(-1)) monitor ed as percentage egg reduction and cure rate was investigated in S. ma nsoni infected school-children. A total of 506 school-children (8-16 y ears of age) were classified into three groups according to their inte nsity of infection, heavy [>500 eggs per grams (epg)], moderate (100-5 00 epg) and light (<100 epg), after examination of three stool samples (three slides per sample) on three consecutive days. Percentage egg r eduction and cure rate were monitored 4 and 10 weeks post-treatment fo r each dose regimen in the different test groups. Before testing the e fficacy of either brand in patients, the pharmacokinetic parameters of the two brands were studied in non-infected normal volunteers. Statis tical analysis of the pharmacokinetic parameters of brand 1 vs brand 2 (in a dose of 20 or 40 mg kg(-1)) revealed no significant difference in elimination (ke), absorption rate constant (ka), elimination half l ife (t1/2e), area under the time-concentration curve (Auc), serum maxi mum concentration (Cp(max)) and time to maximum concentration (T-max). As regards the efficacy of test drugs, statistical analysis revealed that up to 10 weeks posttreatment the two brands of PZQ in full dose w ere equally effective in reducing egg count as their half doses except in heavily infected cases treated with brand 2 of PZQ. In this group a significantly higher percentage of egg reduction was recorded in pat ients receiving 40 mg kg(-1) when compared to those treated with 20 mg kg(-1). Considering patients cured (passing no viable eggs), higher d oses of brand 1 and brand 2 produced in several instances a higher per centage of cures than lower doses. However comparison of brand 1 to br and 2 of PZQ whether in full or half dose did not reveal any statistic ally significant difference in either the cure rate or percent egg red uction.