Nifedipine‐induced Acute Psychosis

A 62-year-old man was started on nifedipine, 10 mg three times daily, for treatment of angina pectoris. Two hours after taking nifedipine on the second day of therapy, the patient experienced severe abdominal cramps, diarrhea, and extreme irritability. He was unable to “sit still,” became panic stricken, and kept on pacing up and down the floor. The ringing of the phone or barking of the neighbor's dog upset him and he did not sleep all night. The wife noticed that he felt worse each time he took the medicine, and as he became extremely agitated, belligerent, tremulous, and depressed, they decided to discontinue the drug. The patient's mental status returned to normal over the next two days with the recurrence of his angina. He had exhibited no signs of bizarre behavior or depression in the past. This patient may be hypersensitive to this drug. He was not on any other therapy. There was no evidence of impairment of hepatic or renal function. Nervousness, shakiness, syncope, edema, and weight gain all have been reported as side effects of this drug. Symptoms such as insomnia, hyperexcitability, pacing, and inability to sit still may be acute dystonic reactions to a medication. It is possible that nifedipine, a calcium channel blocker, decreases plasma dopamine beta-hydroxylase levels, inducing these side effects. Review of the literature revealed a recent report in which another calcium antagonist, diltiazem, caused these kinds of reactions.1