Pregabalin or Lyricais FDA approved for the treatment of post herpetic neuralgia and painful diabetic neuropathic pain. It is also approved as an add on drug for partial onset epilepsy.

Lyrica works (at least in the area of neuropathic pain therapy) by binding to the alpha-2 delta subunit of a voltage-gated calcium channel in the brain and spinal cord. This reduces flow of calcium into the axon during depolarization (firing) of the neuron thereby reducing neurotransmitter release from that neuron. This is the same method that neurontin uses. Neurontin absorption percentage, however, decreases with increasing dose. Lyrica does not have this disadvantage and therefore, at least in theory, has the potential to have a more robust clinical effect. I say in theory, because to my knowledge, there have been no studies taking patients who failed neurontin for neuropathic pain or epilepsy and switched them to lyrica to show if some benefit.

In studies of painful diabetic neuropathy, Lyrica at 300 mg daily dose was shown to reduce pain scores by at least 30% about 2/3rds of the time. A 30% pain score reduction has been shown to correspond to a reduction the patient felt was clinically meaningful. Benefits were seen by the end of the first week. Dizziness and sleepiness were the most common side effect but overall the drug is very well tolerated. For a diabetic, the side effect of weight gain is likely to be most troublesome in its use. Patients in these trials were excluded if they had previously failed high dose neurontin.

Lyrica was also shown to be useful in the treatment of post-herpetic neuralgia. Response rates are somewhat lower than with painful diabetic neuropathy but occur at lower doses of Lyrica with 150 mg being an adequate dose. The response was rapid and seen during the first week. I suspect the reason for this is the general older patient population of PHN who would clear the drug from their blood stream more slowly. Again, patients who had previously failed high dose neurontin were excluded from these studies as well.

Lyrica was released in a large number of tablet sizes all at the same price. For this reason, it is reasonable to try to take the medicine twice daily with larger pill sizes then three times daily with smaller pill sizes. It also means that compared to neurontin, the agent it most closely resembles, it is more expensive than neurontin at lower doses of neurontin (something like 1800 mg or less) but cheaper than neurontin at higher doses of neurontin.

Lyrica has been approved as an add on agent for partial onset seizures. Its mechanism of action is the same as neurontin has been approved for twice daily dosing which is a big advantage compared to neurontin. In addition, because the drug was priced to be competitive against Cymbalta®, it is less expensive than many of the newer AEDs at typical anti-epileptic doses.

The use of pregabalin in anxiety is beyond the scope of this web site but promises to be a hot topic. In September 2004, the FDA denied its approval in this area.