The anti-cancer drug-induced pica in rats is related to their clinical emetogenic potential.

Cancer chemotherapy is frequently accompanied by severe emesis. The anti-cancer drugs are classified according to their clinical emetogenic potential. We have already found that kaolin ingestion behavior "pica" is analogous to emesis in rats. The aim of this study was to examine the effects of the clinical emetogenic potential of anti-cancer drugs on the induction of the pica in rats. Rats were housed in individual cages with free access to food and kaolin pellets and the daily food and kaolin intakes were measured for 3 days after the intraperitoneal administration of anti-cancer drugs (cisplatin, cyclophosphamide, actinomycin D, 5-fluorouracil and vincristine). The drugs with high potential for inducing emesis, such as cisplatin and cyclophosphamide, induced pica in all animals on the day of administration and the behavior lasted during the observation period. The drugs with moderate emetogenic potential, i.e. actinomycin D and 5-fluorouracil, also induced pica on the first and second day after the drug administration but the kaolin intake was less than that of the drugs with high potential. Vincristine, a drug with low emetogenic potential, slightly increased the kaolin intake in rats on the only first day of the administration. Cyclophosphamide, actinomycin D and vincristine induced anorexia and decreased their body weight during the observation period. These results suggested that the both amounts of kaolin intake and duration of behavior in the anti-cancer drug-induced pica are related to the clinical emetogenic potential of the drugs and the incidence of the anorexia is not related to their emetogenic potential.