Topiramate in chronic lumbar radicular pain.
Chronic lumbar radicular pain is the most common neuropathic pain syndrome. This was a double-blind, randomized, 2-period crossover trial of topiramate (50 to 400 mg) and diphenhydramine (6.25 to 50 mg) as active placebo to assess the efficacy of topiramate. Each period consisted of a 4-week escalation, a 2-week maintenance at the highest tolerated dose, and a 2-week taper. Main outcome was the mean daily leg pain score on a 0 to 10 scale during the maintenance period. Global pain relief was assessed on a 6-level category scale. In the 29 of 42 patients who completed the study, topiramate reduced leg pain by a mean of 19% (P = .065). Global pain relief scores were significantly better on topiramate (P < .005). Mean doses were topiramate 200 mg and diphenhydramine 40 mg. We concluded that topiramate treatment might reduce chronic sciatica in some patients but causes frequent side effects and dropouts. We would not recommend topiramate unless studies of alternative regimens showed a better therapeutic ratio.


CONCLUSIONS
The anticonvulsant topiramate might reduce chronic lumbar nerve root pain through effects such as blockade of voltage-gated sodium channels and AMPA/kainite glutamate receptors, modulation of voltage-gated calcium channels, and gamma-aminobutyric acid agonist-like effects.
Khoromi
Suzan
S
Pain and Neurosensory Mechanisms Branch, National Institute of Dental and Craniofacial Research, Bethesda, MD 20892-1302, USA. khoromisu@mail.nih.gov
Patsalides
Athos
A
Parada
Suzan
S
Salehi
Vesta
V
Meegan
Jennifer M
JM
Max
Mitchell B
MB
D000328:Adult; D000368:Aged; D000700:Analgesics / Q000008:administration & dosage / Q000009:adverse effects; D000927:Anticonvulsants / Q000008:administration & dosage / Q000009:adverse effects; D002908:Chronic Disease; D018592:Cross-Over Studies; D004155:Diphenhydramine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D005632:Fructose / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000188:drug therapy* / Q000503:physiopathology; D007473:Ion Channels / Q000187:drug effects; D017116:Low Back Pain / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data; D010919:Placebos; D011843:Radiculopathy / Q000188:drug therapy* / Q000503:physiopathology; D017470:Receptors, Glutamate / Q000187:drug effects; D000077236:Topiramate; D016896:Treatment Outcome
D000700:Analgesics; D000927:Anticonvulsants; D007473:Ion Channels; D010919:Placebos; D017470:Receptors, Glutamate; D000077236:Topiramate; D005632:Fructose; D004155:Diphenhydramine