United States of America - The manufacturer of terbinafine (Lamictal®) has provided new prescribing information concerning rare cases of hepatic failure, some leading to death or liver transplant. Terbinafine is used for the treatment of onychomycosis.

In the majority of the cases reported, patients had serious underlying systemic conditions and an uncertain causal relationship with terbinafine. Although postmarketing surveillance have shown no increase in the frequency of these adverse events, proper patient selection should be reinforced.

A revision has been made to the warnings, precautions and adverse reactions sections of the labelling. Terbinafine is not recommended for patients with chronic or active liver disease. Pretreatment serum transaminase tests are advised for all patients, irrespective of preexisting liver disease and patients should be warned to report immediately any symptoms, such as persistent nausea, anorexia, fatigue, vomiting, right upper abdominal pain, jaundice, dark urine or pale stools.

In vitro studies have also shown that terbinafine inhibits CYP2D6-medicated metabolism, which may be of clinical relevance for compounds predominantly metabolized by this enzyme such as tricyclic antidepressants, beta-blockers, selective serotonin reuptake inhibitors (SSRIs), and monoamine oxidase (MAO) inhibitors.

Reference: Letter from Novartis, New Jersey, USA, dated May 2001.