Two-step progression of varenicline-induced autoimmune hepatitis.

We describe a rare case of drug-induced hepatitis due to the smoking cessation agent varenicline in a 46-year-old Asian woman. The liver injury progressed in two steps. First, the liver injury started in the absence of viral/autoimmune responses, and withdrawal of varenicline lowered the increase in the levels of liver enzymes immediately. Such findings suggested varenicline-induced liver injury. Second, hepatitis recurred in association with conversion of antinuclear antibody from negative to positive about 8 weeks after the initial episode. Histology upon recurrence of liver injury revealed interface hepatitis with lymphocytic and lymphoplasmacytic portal inflammatory infiltrates extending into lobules. Such findings suggested autoimmune hepatitis. Corticosteroid treatment was effective for recurrent hepatitis. The clinical course suggests that varenicline caused drug-induced liver injury and subsequent autoimmune hepatitis. Some autoimmune changes were probably involved in the mechanism of varenicline-induced liver injury.