GABA Analogues
Gabapentin and pregabalin:
- Are both structural analogues of GABA
- Have no direct action on the GABAA receptor
- Act on the α2δ subunit of voltage gated Ca2+ channels in the CNS, inhibiting neurotransmitter release
- May have some NMDA receptor activity
Comparison of GABA Analogues
| Property | Gabapentin | Pregabalin |
|---|---|---|
| Uses | Focal seizures, neuropathic pain | Focal seizures, neuropathic pain, anxiety |
| Route of Administration | PO | |
| Dosing | 100mg TDS, increasing up to 1200mg TDS | 50mg BD/TDS, up to 600mg in divided doses (BD or TDS) |
| Absorption | PO bioavailability of 60%, decreases with increasing dose due to saturation of transporter | 90% PO bioavailability, delayed by food but unaffected by dose |
| Distribution | Minimally protein bound | Minimally protein bound |
| Metabolism | Not metabolised | Not metabolised |
| Elimination | Renal elimination of active drug, t1/2β 6 hours | Renal elimination of active drug, t1/2β 6 hours |
| CNS | Drowsiness, ataxia, psychiatric symptoms | Confusion, psychiatric symptoms, drowsiness |
| GIT | N/V |
References
- Taylor CP, Angelotti T, Fauman E. Pharmacology and mechanism of action of pregabalin: the calcium channel alpha2-delta (alpha2-delta) subunit as a target for antiepileptic drug discovery. Epilepsy Res. 2007 Feb;73(2):137-50. Epub 2006 Nov 28.
- Peck TE, Hill SA. Pharmacology for Anaesthesia and Intensive Care. 4th Ed. Cambridge University Press. 2014.