Gabapentin

How it works

It binds the alpha-2-delta subunit of voltage-gated calcium channels, reducing excitatory neurotransmitter release and modulating neuronal excitability.

Prescribing in practice

• It is renally cleared, so reduce the dose in renal impairment common in older people, and titrate slowly to limit dizziness, sedation and falls.
• Gabapentin is a controlled drug with potential for misuse and dependence; the combination with opioids increases the risk of respiratory depression and sedation.
• Withdraw gradually to avoid withdrawal symptoms and, in epilepsy, the risk of rebound seizures.

Monitoring

Monitor for sedation, dizziness, mood changes and falls, and review renal function as a guide to dosing.

Counselling the patient

• Drowsiness and dizziness are common at first; take care with driving and avoid falls.
• Do not stop suddenly, as this can cause withdrawal effects.
• Tell your team about opioid painkillers, as the combination can dangerously slow breathing.

Evidence & guidelines

MHRA guidance reclassified gabapentin as a controlled drug and warns of respiratory depression with concomitant opioids or in those with reduced respiratory reserve, including older patients.