What is gabapentin?
Gabapentin is an anticonvulsant that is used to treat certain types of epilepsy. It is also used to treat neuropathic pain, a type of pain or altered sensation caused by damage to the nerves. Gabapentin is successfully being used to treat skin conditions associated with pain or pruritus of neuropathic origin.
What is gabapentin used for?
Gabapentin is proving to be useful in reducing the symptoms of pain and unpleasant sensations caused by the following skin conditions:
- Pruritus (itch)
- In patients on haemodialysis (renal itch)
- In patients with brachioradial pruritus
- Chronic pruritus of unknown origin
- in patients with dysaesthetic vulvodynia or vestibulodynia
- Post-herpetic neuralgia (see shingles)
Pain and/or pruritus arising from these conditions are defined as sympathetically maintained pain (SMP). The pain is usually described as having a burning sensation and is often in response to stimuli that does not ordinarily cause pain. This pain and pruritus originate from the nervous system.
Dosage of gabapentin
The use of gabapentin for neuropathic pain/pruritus is recommended only in patients over 18 years of age. The starting dose is 900mg/day (given as 300mg 3 times daily) and increased if necessary based on response. The maximum daily dose is 3600mg.
Dosage may need to be adjusted in those with impaired renal function. Patients on haemodialysis should start on a loading dose of 300-400mg, followed by 200-300mg after every 4 hours of haemodialysis.
What are the side effects of gabapentin?
The side effects of gabapentin include:
- Dry mouth
- Unsteadiness, reduced co-ordination, or slowed reaction
- Constipation, diarrhoea
- Peripheral oedema (swelling around the ankles)
- Dizziness, confusion, loss of concentration
- Weight gain
- Changes in appetite
- Nausea, vomiting, indigestion.
See your doctor if these effects occur and are of concern to you. Patients over the age of 65 years have an increased chance of getting side effects.
We suggest you refer to your national drug approval agency such as the Australian Therapeutic Goods Administration (TGA), US Food and Drug Administration (FDA), UK Medicines and Healthcare products regulatory agency (MHRA) / emc, and NZ Medsafe, or a national or state-approved formulary eg, the New Zealand Formulary (NZF) and New Zealand Formulary for Children (NZFC) and the British National Formulary (BNF) and British National Formulary for Children (BNFC).