A man came to my office complaining of an extensive rash. On examination, I discovered herpes zoster covering nearly his entire left upper leg. Astonishingly, the patient told me that it did not hurt at all. According to his chart, he had been taking desipramine 50 mg b.i.d. for 10 years to treat adult attention-deficit disorder. I believe the desipramine has deadened his pain receptors. Could this agent be used as temporary pain relief in other patients with herpes zoster or other excruciating conditions?
—Maureen G. Purtell, PhD, ARNP, BC, Nashua, N.H.

Desipramine is a first-generation tricyclic antidepressant (TCA). Nineteen of 26 postherpetic neuralgia (PHN) patients completed a randomized double-blind crossover study involving six weeks of treatment with desipramine (mean dose 167 mg/day) and placebo. At least moderate relief was reported in 12 with desipramine and two with placebo. From weeks three through six, statistically significant pain relief was observed with desipramine (Clin Pharmacol Ther. 1990;47:305-312). Many publications that review the use of TCAs for the treatment of PHN predominantly discuss nortriptyline and amitriptyline. Similar analgesic effects are offered by both agents; however, less sedation and cognitive impairment is associated with nortriptyline (J Drugs Dermatol. 2006;5:938-941 and Drugs. 2000;59:1113-1126).
—Philip R. Cohen, MD (100-5)

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