[Interactions of cytostatic agents with other drugs].

With the degree of polypharmacy currently practiced in the field of oncology, there are undoubtedly many drug interactions. In the present study the influence of "non-cytotoxic" drugs on anticancer drugs is discussed, but not the reverse. Not only is the augmentation (reversal of multidrug resistance) or the reduction of antitumor properties of cytotoxic drugs observed, but also cytostatic activities of "non-cytotoxic" drugs themselves. Examples are calmodulin inhibitors such as phenothiazines and tricyclic antidepressants. Interactions may also increase side effects of cytostatic drugs or even neutralize the antitumoral activity. To ensure that interactions are not overlooked, all medicaments being administered should be listed. It is, however, not feasible yet to determine serum concentrations of all the drugs given to the patient. The antitumor activity of supportive care could be evaluated in randomized studies (e.g. cytostatic drugs +/- antidepressants).