Prescrire international
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Prescrire international · Aug 2002
Gabapentin: new indication. In postherpetic neuralgia when amitriptyline fails.
(1) Postherpetic pain is infrequent, but the incidence increases with age. (2) The reference treatment for postherpetic pain is oral amitriptyline or desipramine. (3) Gabapentin, an antiepileptic agent, is the first drug to be granted specific approval in France for the treatment of postherpetic pain. (4) In two placebo-controlled trials, gabapentin at a dose of between 1 800 and 3 600 mg/day halved the intensity of pain in about one in three patients. In comparison, pain improved in about 50% of patients taking amitriptyline in clinical trials. (5) Both gabapentin and amitriptyline provoke sedation, but dizziness and peripheral oedema are more frequent on gabapentin, while atropinic effects predominate with amitriptyline. (6) Daily treatment is 10 times more costly in France. (7) In practice, the standard treatment of postherpetic pain remains oral amitriptyline or desipramine. Gabapentin is an alternative, given its different safety profile.
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Prescrire international · Aug 2002
Oral transmucosal fentanyl: new preparation. For breakthrough cancer pain when morphine fails.
(1) Some cancer patients suffer occasional breakthrough pain despite well-conducted opiate treatment, warranting the use of immediate-release oral morphine. (2) A fentanyl preparation for oral transmucosal administration has just been granted this indication in France. (3) The evaluation file mainly contains results from a randomised double-blind cross-over trial comparing transmucosal fentanyl with oral morphine tablets in cancer patients. It showed a small gain in terms of rapidity and efficacy of pain relief with fentanyl relative to morphine, but this was of dubious clinical relevance. (4) The adverse effects of oral transmucosal fentanyl are those of all opiates, such as drowsiness, dizziness, nausea, vomiting and confusion. (5) The oral transmucosal fentanyl preparation has the taste and appearance of a lollipop, and may therefore be attractive to children. The packaging seems to take this risk into account, but precautions must be taken to keep this treatment away from children, especially after opening. (6) Immediate-release oral morphine remains the standard treatment for breakthrough pain in patients receiving opiate therapy. If it is inadequate, oral transmucosal fentanyl may sometimes be slightly better.
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Prescrire international · Aug 2002
Oral pilocarpine: new preparation. Xerostomia after radiation therapy: moderately effective but costly.
(1) Dry mouth (xerostomia) is a frequent complication of radiation therapy for cancers of the ear nose and throat. Local measures such as saliva substitutes and anetholtrithione are either moderately effective, inadequately evaluated or little better than placebo. (2) Marketing authorization has been granted in France for an oral formulation of pilocarpine, an old parasympathomimetic agent, in the treatment of radiotherapy-induced xerostomia. (3) According to the results of two double-blind trials, pilocarpine (15-30 mg/day) improves symptoms in about 50 % of patients, compared to improvement in 25% of patients taking placebo. ⋯ It is not known whether pilocarpine helps prevent the complications of xerostomia. (4) Most adverse effects of pilocarpine are due to its parasympathomimetic effects, such as sweating, urinary frequency, flushing, rhinitis and nausea. Pilocarpine must therefore be used with caution in patients with asthma, cardiac arrhythmia, iridocyclitis, and closed-angle glaucoma. (5) In France, this pilocarpine formulation costs 18 times more than a preparation of pilocarpine 2% eye drops used orally (off licence). (6) In practice, patients needing symptomatic treatment of xerostomia after radiotherapy may benefit from oral pilocarpine but, given its limited efficacy and its adverse effects, other local treatments should be tried first.