GABA Analogues

Gabapentin and pregabalin:

  • Are both structual 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

  1. 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.
  2. Peck TE, Hill SA. Pharmacology for Anaesthesia and Intensive Care. 4th Ed. Cambridge University Press. 2014.
Last updated 2017-09-24

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