The classification is based on metabolic consideration. Pregabalin undergoes negligible metabolism. It is mainly excreted unchanged in urine. Hepatic enzyme induction is unlikely with pregabalin.

Gamma-aminobutyric acid analogue.

Pregabalin binds to a subunit of calcium channels in the central nervous system, but mechanism of action is unknown. It is structurally and pharmacologically related to gabapentin. Pregabalin is used in epilepsy, neuropathic pain and Generalized Anxiety Disorder. Common adverse effects that can be mistaken for porphyria symptoms are vomiting, constipation, confusion, irritability, paraesthesia, ataxia, fatigue.

No significant hepatic metabolic load.

Pregabalin is predominantly excreted unchanged in the urine and undergoes negligible metabolism in humans (<2% of a dose recovered in urine as metabolites). It does not inhibit drug metabolism in vitro (SPC pregabalin updated: 2007-06). Unpublished data suggest no change in the pharmacokinetics of concomitantly administered antiepileptic agents (unspecified) following add-on therapy with pregabalin (Bialer et al, 2001).

Uneventful use reported in 8 patients with acute porphyria.