In therapy we may express the benefit of a drug by the Number Needed to Treat or NNT. That is the number of patients you have to give the drug to benefit one patient. For example, an NNT of 2 means you have to give the drug to 2 patients for the benefit of one patient. If the NNT is 5, it means you have to give the drug to 5 patients to benefit one patient. The higher the NNT number the poorer the drug result. The ideal drug has an NNT of 1: each patient taking the drug is benefitting from it.
Conversely, we may also express the side effects and complications of the drug by the Number Needed to Harm or NNH. In that case, the higher the number, the least toxic the drug. In case the NNH number is lower than the NNT, the drug is toxic to more patients than it is beneficial to some.
Two very serious reviews have had a look at neuropathic pains. Because there is variation from one type of pain to another, I have summarized the results for diabetic neuropathy so we can compare what's comparable. Don't go away, it's got something to do with fibromyalgia!
NNT (the lower the better)
Pregabalin (Lyrica): 5
NNH (the higher the better)
There is no discussion that carbamazepine and phenytoin are the best: Lower NNTs and higher NNHs
Gabapentin is a shame: higher NNT and an NNH lower than the NNT!
Pregabalin (Lyrica) which is the new one on a multi-billion market has a higher NNT than the others and should never have been accepted. Its NNH is close to 1 (unstated in the studies but obvious by the side effects numbers in reference 3). This means that it is almost always toxic and seldom beneficial.
1- Cochrane Database Syst Rev. 2010 Jan 20;(1)
Anticonvulsant drugs for acute and chronic pain. Wiffen PJ, Collins S, McQuay HJ, Carroll D, Jadad A, Moore RA.
2- Cochrane Database Syst Rev. 2009 Jul 8;(3)
Pregabalin for acute and chronic pain in adults. Moore RA, Straube S, Wiffen PJ, Derry S, McQuay HJ.
3- Neurology. 2010 Mar 2; 74(9):755-61.
Cognitive effects of pregabalin in healthy volunteers: a double-blind, placebo-controlled trial. Salinsky M, Storzbach D, Munoz S.
Summary: All healthy volunteers had negative cognitive effects with Pregabalin.
The above is an extract of Florence Nightingale Newsletter.
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