Objective: To report an association between acute renal failure and varenicline.
Case summary: A 53-year-old white male with preexisting moderate renal insufficiency was admitted to the hospital for acute renal failure following a change in serum creatinine from 4 mg/dL at baseline to 10.6 mg/dL upon admission. One week prior to admission, the patient started taking varenicline (dose undetermined) for smoking cessation and had been stable on all other medications for 2 months prior to admission. All hospital workup tests were negative for prerenal azotemia, postrenal obstruction, and intrinsic renal disease. Varenicline was discontinued on admission. With no other changes in therapy, the serum creatinine level decreased each day of the patient's 5-day hospitalization to 8.6 mg/dL upon discharge, and it was 6.4 mg/dL at a follow-up appointment 2 weeks after discharge.
Discussion: Varenicline is a novel medication that is effective for smoking cessation. Adverse effects are generally mild and self-limiting, with gastro-intestinal effects most commonly reported. According to the package insert, varenicline does not change creatinine clearance to any appreciable extent, but it should be used with caution in patients with renal impairment. It also states that varenicline can cause acute renal failure rarely; to our knowledge, this is the first published association of varenicline with renal effects. Use of the Naranjo probability scale showed varenicline to be the probable cause of renal dysfunction in this patient because of the temporal relationship and lack of alternative causes.
Conclusions: Although there was a probable relationship between varenicline and acute renal failure in this patient, the significant benefit of smoking cessation to overall health outweighs the risk of this rare adverse effect. Clinicians should be aware of this potential adverse effect and should monitor renal function upon initiation of varenicline therapy, especially in patients with chronic kidney disease.