Last updated on April 2007

Effects of Pregabalin on Mechanical Hyperalgesia

Brief description of study

The aim of this randomized placebo-controlled study is to evaluate the effects of analgetics for neuropathic pain on mechanical hyperalgesia as a kind of evoked pain. Therefore the number of responders and non-responders on pregabalin will be evaluated in respect of mechanical hyperalgesia (stimulus-response-function (SRF) on static punctual stimuli evoking pain determined via pinprick). The hypothesis is that in the placebo group the amount of non-responders is increased.

Detailed Study Description

This randomized controlled trial is intended to be the first in a series of trials that will assess the efficacy of drugs, which relieve neuropathic pain, on stimulus-evoked pain (here: mechanical hyperalgesia to static punctate stimuli). Most drugs in this class (e.g. Gabapentin or NMDA receptor inhibitors) have NNT beyond 3 in patients with chronic pain, due to a response rate of 30 to 50 %. One potential reason for this low overall efficacy might be the presence of different pathophysiological mechanisms in subgroups of patients, who suffer from the same disease (e.g. postherpetic neuralgia, diabetic neuropathy). These mechanisms may include central sensitization on one hand and peripheral degeneration of afferent fibers on the other hand. In this trial, we will use a battery of mechanical and thermal Quantitative Sensory Tests (QST), using non-nociceptive and low-intensity painful stimuli, to identify a subgroup of patients with mechanical hyperalgesia. To overcome the well-known low response rate in trials with neuropathic pain patients, an enriched design comparing active drugs with placebo will be performed, including only patients with high intensity of on-going pain in combination with mechanical hyperalgesia as sequelae of different, but well defined neurological disorders. The blinded phase of the trial will be restricted to so-called responders, i.e. patients with a clinically meaningful pain reduction of at least 30% in the primary end point (mechanical hyperalgesia). The second objective of this trial is to evaluate, whether the anti-hyperalgesic effect of the active drug is dependent on the QST profile.

Clinical Study Identifier: NCT00310583

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