CHEMOPREVENTION OF RESPIRATORY-TRACT NEOPLASIA IN THE HAMSTER BY OLTIPRAZ, ALONE AND IN COMBINATION

Two doses of oltipraz (300, 600 mg/kg diet) and alpha-difluoromethylor nithine DFMO; 1600, 3200 mg/kg diet), alone and in combinations with N -(4-hydroxyphenyl) retinamide (4-HPR; 98, 196 mg/kg diet) and/or beta- carotene (3, 1.5 mg; sc, 2x/week), were investigated for prevention of hamster respiratory carcinogenesis. After 25 weeks, only high dose ol tipraz (-100%) inhibited the incidence of DEN-induced (17.8 mg/kg BW, sc, 2x/week, 20 weeks) bronchial carcinomas when given alone. Low dose oltipraz (-34%, n.s.) synergistically decreased carcinoma incidence i n combinations with 4-HPR (-80%), beta-carotene (-90%) or both (-100%) . Other effective combinations were low dose DFMO + beta-carotene (-64 %) and high dose DFMO with 4-HPR (-56%), beta-carotene (-63%) or both (-67%).