Control of neuropathic pain with topical amitriptyline

Kopsky et al. Central Neuropathic Pain in a Patient with Multiple Sclerosis Treated Successfully with Topical Amitriptyline. Case Report Med. 2012;2012:471835.


Central neuropathic pain in MSers is a common debilitating symptom, which is mostly treated with tricyclic antidepressants or antiepileptics (e.g. gabapentin, carbamazepine, oxcarbamazepine). Unfortunately, the use of these drugs is often limited due to adverse events; in particular sedation and cognitive slowing. This case investigated the analgesic effect of topical amitriptyline 5% and 10% cream in a patient with central neuropathic pain due to MS. The analgesic effect of topical amitriptyline cream on neuropathic pain was dose related. To evaluate whether this analgesic effect is due to the active compound or placebo, they conducted a double-blind placebo-controlled n-of-1 study with amitriptyline 5% cream and placebo. The instruction was to alternate the creams every week following the pattern ABAB, with an escape possibility of amitriptyline 10% cream. The result was a complete pain reduction after application of cream B, while most of the time cream A did not reduce the pain. The MSer could correctly unblind both creams, determining B as active. She noted that in the week of using the active cream no allodynia (the medical term that describes the syndrome of a non-painful stimulus causing pain; allodynia is typical of neuropathic pain)  was present, with a carryover effect of one day.

"Amitriptyline is a tricyclic antidepressant (TCA) that used to be used to treat depression. It is not used for that purpose anymore as it is too sedating at doses that work for depression. Neurologists use it to manage pain. An advantage of amitriptyline is that is a sedative and helps you sleep; this is useful if you have pain. 
Amitriptyline is not addictive and your body does not get used to it; i.e. you don't have to increase the dose to maintain the desired effect once you get to the correct dose. I am a big fan of  amitriptyline and use a lot of it."

"What is wrong with this study? May be the MSer was not unblinded, i.e. the cream with amitriptyline smelt, felt or caused a sensation that unblinded the study subject. What needs to be done is a larger study, what do you think?"

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