Neurontin (gabapentin) was developed as an anticonvulsant for use in epilepsy. More recently it has been found to be effective in relieving symptoms in people suffering from fibromyalgia or chronic neuropathic pain including diabetic neuropathy and post-herpetic neuralgia (post shingles pain). Gabapentin is also used to prevent and treat migraine.
Gabapentin is thought to work by binding to calcium channels found on nerve cells in the brain and spinal cord. This in turn affects the release of various neurotransmitters that are responsible for conducting messages between these nerve cells.
In particular gabapentin inhibits the release of a neurotransmitter called glutamate, which is involved in transmitting pain signals in the brain and nervous system. As gabapentin reduces the release of glutamate it can be effective in treating nerve (neuropathic) pain that may have resulted from damage to, or a disturbance in, the function of nerves.
For adults over 18 years with neuropathic pain:
- 300 mg once on day 1,
- 300 mg twice on day 2,
- 300 mg three times on day 3
the dose can then be increased according to response in steps of 300 mg (in 3 divided doses) every 2–3 days up to max. 3,600 mg daily
For migraine prophylaxis [unlicensed]:
- Start at 300 mg daily,
- This can be increased according to response up to 2,400 mg daily in divided doses.
Gabapentin can be taken before or after meals. The tablets/capsules should be swallowed with a drink of water.
Once you are taking a regular amount of gabapentin, try to take your doses at the same times each day. This will help you to avoid missing any of your doses. If you do forget to take a dose, take it as soon as you remember, but do not take two doses together to make up for a forgotten dose.
Do not stop taking gabapentin unless you have discussed the matter with your doctor or pharmacist.
If you take an antacid or indigestion remedy, do not take it during the two hours before and the two hours after you take gabapentin. This is because they interfere with the way gabapentin works.
Side effects may include:
- Problems with muscle co-ordination
- Viral infections
- Jerky movements
- Increased abnormal muscular activity
- Changes in touch sensation
- Loss of memory
- Difficulty in sleeping
- Irregular eye movements
- Appetite changes
- Decrease in white blood cell count
- Abnormal thoughts
- High blood pressure
- Facial swelling Skin reactions such as rash
Note that this is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
Migraine prophylaxis is an unlicensed indication for gabapentin. This means that the manufacturers do not recommend its use in this condition but there is enough evidence for a doctor to believe that it will be both effective and safe. The doctor takes personal responsibility for the prescription.
If you experience any of the following symptoms, contact your doctor or pharmacist for advice straight away:
- Severe stomach pain with sickness,
- A skin rash, or any swelling of your mouth or face (these may be symptoms of an allergic reaction),
- Any yellowing of your skin or of the whites of your eyes,
- Any unusual bruising or bleeding.
Gabapentin might make you feel dizzy or sleepy and so may reduce your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance. If you feel sleepy while taking this medicine this could be made worse by drinking alcohol.
The patient information leaflet (PIL) is a leaflet containing specific information about medical conditions, doses and side effects. You can download a copy of the PIL here:
Patient Info Leaflet