Risk identification using structural concepts: the potential carcinogenicity of praziquantel.

The potential of praziquantel (PZ) to induce cancers in rodents was evaluated using a structure-activity relational expert system (CASE/MULTICASE). The analyses indicated that based upon structural features PZ had the potential for being a "nongenotoxic" carcinogen. The potential risk to humans of nongenotoxic carcinogens is considered to be much less than that posed by "genotoxic" ones. Moreover, PZ has demonstrated therapeutic effectiveness against parasitic diseases that affect millions of individuals. Additionally, PZ was developed to replace antiparasitic agents which were genotoxic rodent carcinogens. Thus, on balance, the beneficial effects of PZ appear to outweigh its potential for causing harm to humans.