Neuropsychotropic drugs as adjuncts in the treatment of cancer pain.

Opiates remain the mainstay of cancer pain treatment, used in a logical and stepwise fashion with adjunctive therapies as needed. Certain neuropsychotropic drugs may enhance the analgesia produced by opiates and may occasionally be used in place of opiates. Some of these drugs may also provide additional psychoactive benefits. The types of neuropsychotropic drugs that may be useful in treating cancer pain include the tricyclic antidepressants, anticonvulsants, neuroleptics, antihistamines, psychostimulants, and benzodiazepines, as well as systemic local anesthetics. This article reviews the general principles of using adjunctive medications to achieve maximal analgesic benefit with the least number of side effects, and describes each class of neuropsychotropic drug, their proposed mechanism of analgesia, and appropriate use in cancer patients.