A case of flunarizine-induced movement disorder

Abstract

Flunarizine is a calcium channel antagonist widely used for the treatment of migraine. This can cause side effects like movement disorders with longstanding use in the elderly, especially females. This is the case report of a 56-year-old female, taking flunarizine for 6 months, who presented with a movement disorder.

INTRODUCTION

Flunarizine is a selective calcium channel blocker, effective in the treatment of migraine, peripheral vascular disease, and vertigo. Apart from calcium entry blocking, it has antihistaminic, antiserotonergic, and antidopaminergic properties.[¹] Flunarizine binds with Calmodulin, which prevents calcium influx and thus vasoconstriction. Flunarizine is 85% absorbed orally and is 99% protein bound. It is metabolized in the liver. Flunarizine causes movement disorders such as Parkinsonism, orobuccolingual dyskinesia, dystonia, and akathisia.[²] The first case of flunarizine-induced extrapyramidal side effect was reported in 1984. Old age, female sex, and comorbidities like essential tremor would increase susceptibility to flunarizine-induced movement disorder.

Flunarizine is very commonly prescribed in general and neurological practice in the present day and age and having such a distressing side effect can be socially awkward and potentially harassing for the patient. Knowledge about this potential side effect and warning patients about the same can help alleviate the patients' anxiety.

This article is intended to spread awareness about the same.

CASE REPORT

A 56-year-old female presented in the neurology outpatient department with complaints of involuntary jaw movements for the past 10 days. She was a known case of dilated cardiomyopathy with moderate left ventricular dysfunction, with normal liver and renal function. She was taking atorvastatin 10, nitroglycerin 2.6 mg, and torasemide-spironolactone (10/50) for the past 1 year. She was also taking flunarizine 20 mg/day for episodic migraine for the past 6 months. On examination, the patient was conscious and oriented. She had lower jaw tremor– rhythmic, side-to-side movement of lower jaw [Video 1]. There was no head node, voice tremor, or lingual dyskinesia. Examination of the nervous system revealed no other abnormalities. Magnetic resonance imaging brain revealed no abnormality. Other causes of jaw tremor were ruled out. Since flunarizine has been well-documented to cause Extrapyramidal symptoms (EPSs), it was stopped and she was treated with trihexyphenidyl. Patient's symptoms subsided within 1 month [Video 2].

DISCUSSION

Drug-induced extrapyramidal side effects vary from Parkinsonism and akathisia to severe neuroleptic malignant syndrome. Extrapyramidal side effects are most commonly caused by typical antipsychotics such as haloperidol and fluphenazine, which antagonize dopamine-2 receptors. Metoclopramide, selective serotonin reuptake inhibitors, serotonin noradrenaline reuptake inhibitors, and noradrenaline dopamine reuptake inhibitors can also cause EPS. Flunarizine is a calcium channel blocker widely prescribed for migraine prophylaxis. At doses of 10–40 mg/day, especially in elderly individuals, flunarizine can cause extrapyramidal side effects.[²] The average onset of movement disorder ranges from 6 to 48 months.[³] Antidopaminergic activity of flunarizine plays an important role in this. Flunarizine blocks dopamine receptors, it has indirect toxic side effects on Dopaminergic neurons, whereas its calcium channel-blocking property inhibits Dopamine neurotransmission also.[⁴] According to Jhang et al., patients taking flunarizine are 8.03 times more likely to develop EPSs.[⁵] In our case, the patient was taking flunarizine 20 mg/day for the past 6 months. She was also taking other medications such as torasemide, atorvastatin, nitroglycerine, and spironolactone. Since flunarizine-induced extrapyramidal side-effect is known even though rarely encountered, flunarizine was stopped, and symptoms completely recovered within 1 month.

The conclusion is that long-term flunarizine should be cautiously used in patients, especially in the elderly, who are more likely to have extrapyramidal side effects.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.