title: Association of pain relief with drug side effects in postherpetic neuralgia: a single-dose study of clonidine, codeine, ibuprofen, and placebo.
abstract: In a randomized, double-blind crossover study, 40 patients with postherpetic neuralgia were given single oral doses of clonidine, 0.2 mg, codeine, 120 mg, ibuprofen, 800 mg, or inert placebo. Pain relief and side effects were recorded for 6 hours. Patients reported significantly more relief after clonidine than after the other three treatments. Codeine and ibuprofen were ineffective. Sedation, dizziness, and other side effects were more frequent after clonidine (74%) or codeine (69%) than after placebo (36%) or ibuprofen (28%). Reported pain relief was greater during trials in which side effects were present. A single, mild side effect was associated with as much additional pain relief as multiple, severe side effects. Clonidine's superiority to codeine, which had a similar incidence of side effects, argues for a specific analgesic effect. In addition, side effects may have contributed to clonidine analgesia, perhaps by suggesting to patients that they had received a potent drug.
authors.affiliation: Neurobiology and Anesthesiology Branch, National Institute of Dental Research, Bethesda, MD 20892.
authors.forename: M B
authors.initials: MB
authors.lastname: Max
authors.forename: S C
authors.initials: SC
authors.lastname: Schafer
authors.forename: M
authors.initials: M
authors.lastname: Culnane
authors.forename: R
authors.initials: R
authors.lastname: Dubner
authors.forename: R H
authors.initials: RH
authors.lastname: Gracely
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002986:Clinical Trials as Topic; D003000:Clonidine / Q000009:adverse effects / Q000627:therapeutic use*; D003061:Codeine / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D006562:Herpes Zoster / Q000150:complications; D006801:Humans; D007052:Ibuprofen / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000188:drug therapy* / Q000209:etiology; D010147:Pain Measurement; D011897:Random Allocation
chemical_list: D003000:Clonidine; D003061:Codeine; D007052:Ibuprofen