Products
Gabapentin is commercially available in the form of capsules and film-coated tablets (Neurontin, generic). It has been approved in many countries since 1994. Pfizer launched pregabalin (Lyrica) as its successor in 2004.
Structure and properties
Gabapentin (C
9
H
17
NO
2
, M
r
= 171.2 g/mol) is structurally a GABA analog and related to baclofen. It exists as a white crystalline powder that is sparingly soluble in water. It is also administered in the form of the prodrug gabapentine acarbil for the treatment of restless legs syndrome.
Effects
Gabapentin (ATC N03AX12) has antiepileptic, analgesic, and sedative properties. The effects are due to binding to the regulatory α
2
-δ-subunit of voltage-gated calcium channels of presynaptic neurons (see under pregabalin). Although gabapentin is structurally a GABA analog, it does not bind to GABA
A
or GABA
B
-receptors, does not inhibit reuptake, and is not metabolized to GABA.
Indications
For the treatment of epilepsy and for the treatment of neuropathic pain in diabetic neuropathy or postherpetic neuralgia. In some countries, gabapentin is also approved for the treatment of restless legs syndrome (eg, United States, Horizant), and it is also used off-label for flushing, pruritus, and nociceptive pain, among other conditions.
Dosage
According to the SmPC. The drug may be taken with or without food. Treatment must be gradually increased in dose over one week and gradually stopped.
Abuse
Gabapentin may be abused as a depressant intoxicant.
Contraindications
- Hypersensitivity
For complete precautions, see the drug label.
Interactions
Gabapentin is excreted unchanged by the kidney. At high doses, it may slightly inhibit CYP2A6. Drug-drug interactions have been noted with naproxen, hydrocodone, morphine, cimetidine, and antacids.
Adverse effects
The most common potential adverse effects include drowsiness, dizziness, ataxia, and viral infections.