A 35-year-old woman notices a red rash over her cheeks, and pain and swelling in both knees as well as several small joints in her hands. She has a history of hypertension and 2 months ago was started on a new medication to control her blood pressure. Her ANA and anti-histone antibodies are positive. Which of the following medications is most likely to cause her condition?

Hydralazine can cause drug-induced lupus (defined by positive ANA and anti-histone antibodies). About 25-30 % of patients treated chronically with hydralazine will develop ANA positivity and about 10-20% of patients with ANA positivity will develop systemic symptoms compatible with lupus, particularly arthralgias. Genetic variation in drug acetylation rates might be a predisposing factor.