Phenytoin as a coanalgesic in cancer pain.
The efficacy of phenytoin (PHT), buprenorphine (Bu), and Bu+PHT for the relief of cancer pain of various etiologies was evaluated in a randomized, double-blind study of 3 groups, each comprised of 25 patients. Treatment duration was 1 month. PHT (100 mg by mouth twice daily) provided greater than 50% pain relief to 18 patients (72%) and greater than 75% relief to 4 (16%). Bu (0.2 mg sublingually twice daily) gave 21 patients (84%) greater than 50% relief and 15 patients (60%) greater than 75% relief. Of the Bu-treated patients, 8 had major side effects, while none of the PHT-treated patients experienced significant untoward reactions. Combined therapy (PHT, 50 mg PO+Bu 0.1 mg SL twice daily) provided greater than 50% pain relief to 22 patients (88%) and greater than 75% to 18 (72%); only 3 patients experienced a significant side effect. This study suggests that phenytoin has mild-to-moderate pain-relieving properties of its own and can significantly enhance buprenorphine analgesia. By permitting a lower opioid dose, it may reduce the occurrence of opioid-related side effects. PHT's lack of serious side effects, as well as its documented anxiolytic and antidepressant actions, may add to its comparative usefulness. Further clinical trials of PHT as a coanalgesic and/or adjuvant agent in cancer pain are warranted.
Yajnik
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Singh
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Singh
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Kumar
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D000328:Adult; D002047:Buprenorphine / Q000008:administration & dosage / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000503:physiopathology*; D010146:Pain / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology; D010672:Phenytoin / Q000008:administration & dosage / Q000627:therapeutic use*
D002047:Buprenorphine; D010672:Phenytoin