Red GabapentinNeurontin (gabapentin) is classified anti-epileptic and is also used for a variety of other indications including:

  • Restless leg syndrome
  • Post-herpetic neuralgia
  • Fibromyalgia
  • Diabetic neuropathy


Exactly how Neurontin (gabapentin) works isn't well known. It is structurally related to the neurotransmitter gamma-aminobutyric acid (GABA), hence the name gabapentin. However, it is not thought to have any significant effect on GABA. The mechanism of action appears to be complex and is thought to work on calcium channels


How To Start Therapy Of Gabapentin

It is nearly universally recommended to start gabapentin at a low dose, and titrate up slowly to effect. There are a few reasons for this:

  • Gabapentin is known to cause a wide range of side effects, many of which are dose related (i.e. higher doses yield more side effects). Starting at a low dose allows the individual taking the medication  to asses tolerability. Side effects also tend to be lessened and will subside when started on a low dose that is increased slowly.
  • Gabapentin has a large effective dosage range, from at little as 200 mg per day to 3,600 mg per day. Such a large range makes it difficult to find an appropriate starting dose. The goal is to find the lowest effective dose, to decrease the risk of side effects. This requires starting at a low dose and increasing slowly to effect.


Common side effects of gabapentin include:

  • Dizziness
  • Somnolence (long lasting drowsiness)
  • Peripheral edema
  • Nausea
  • Lack of energy
  • Diarrhea
  • Weight gain
  • Dry mouth


Most of the above side effects are dose related and are much more likely to occur on high doses.


For nearly all indications, gabapentin is recommended to be started at a low dose, around 300 mg one to three times daily.  Doses are then slowly increased (i.e. titrated) by 400 to 600 mg every four to seven days. The dose in then increased further to a target dose of 600 mg to 3,600 mg per day. 


Some studies suggest, that for most individuals, starting at slightly higher doses (~900 mg) is well tolerated. One study found the following:  

"Starting gabapentin therapy at an initial therapeutic dosage of 900 mg/day is well tolerated by patients with epilepsy and is as safe as initiating with a titration schedule over 3 days. Of the four most common adverse events (somnolence, dizziness, ataxia, fatigue), only one, dizziness, occurred more often in the nontitrated (Rapid initiation) group than in the titrated (Slow initiation) group."

Although the correct starting dose of gabapentin isn't agreed on, and is certainly variable per individual, it would be prudent to start on the lower end and increase to effect.


Summary

  • Gabapentin is associated with a range of dose related side effects including dizziness, somnolence and nausea.
  • It is often recommended to start at a low dose of gabapentin and increase slowly to effect to avoid or lessen side effects.