Reactions 1453 - 25 May 2013

XMetoprolol/propafenone interaction

Tiredness and dyspnoea in an elderly patient: casereport

A 66-year-old woman developed tiredness and dyspnoeadue to an interaction between metoprolol and propafenone.

The woman, who had comorbidities including ischemicheart disease without angina pectoris syndrome and chronicvenous insufficiency, was receiving cardiovascular medicationincluding metoprolol 200 mg/day [route not stated]. Afteradmission with decompensated hypertension, she wasprescribed propafenone 600mg daily [route not stated] asprophylaxis against atrial fibrillation. Later, amlodipine wasadded to her medications. Her hypertension improved;however, she reported increased tiredness and dyspnoea onexertion [durations of treatment to reaction onset not stated].Investigations revealed a serum metoprolol concentration of412.2 µg/L 3 hours after intake, and a metoprolol-α-hydroxymetoprolol metabolic ratio of 104.3.

Metoprolol was reduced to 100mg daily, and the woman’ssymptoms resolved. About 6 months later, she was readmittedwith global cardiac failure with atrial fibrillation with slowventricular response. Metoprolol was reduced to 12.5mg dailyand propafenone was withdrawn. Two weeks later, she washaemodynamically stable and was discharged. Several dayslater, she increased her metoprolol to 100mg daily. At her nextfollow-up, investigations revealed a substantial decrease in hermetoprolol-α-hydroxymetoprolol metabolic ratio followingpropafenone discontinuation.

Author comment: "Our patient suffered from tirednessand dyspnea on exertion likely owing to high metoprololserum concentrations caused by the inhibitory effect ofpropafenone."Duricova J, et al. Clinically important interaction between metoprolol andpropafenone. Canadian Family Physician 59: 373-375, No. 4, Apr 2013 - CzechRepublic 803086991

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Reactions 25 May 2013 No. 14530114-9954/10/1453-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved