Objective: Amlodipine is a dihydropyridine calcium-channel blocker with actions similar to those of nifedipine. It is used in the management of hypertension and angina pectoris. It is generally well tolerated, and its main side effects are dizziness, flushing, headache, hypotension and ankle edema. Gingival hyerplasia may occur. We report 2 cases of a previously unreported adverse effect of amlodipine, oro-lingual dyskinesia
Case: One case is 73 year-old female who lived in an asylum for the old. She had a history of hypertension for 14 years and stroke in 1991. She had taken amlodipine for 7 years. 6 months ago, she complained of anxiety and oro-lingual dyskinesia. After she was treated with procyclidine HCL, madopar and clonazepam, her abnormal movements are modified mildly. Four months later, she could not eat and drink, because her oro-lingual movements were aggravated. All drugs were stoped except amlodipine. 2 weeks later, she was admitted to the hospital because of her poor general condition. In the hospital, amlodipine was discontinued and fluid therapy was done. After 2 week of discontinuation of amlodipine, her oro-lingual movements were disappeared and then she could eat and drink. The other case is 84 year-old female who also lived in asylum for the old and had a history of hypertension. She had taken amlodipine for 6 years. She also had oro-lingual dyskinesia, but her symptoms were not taken our attention because she could eat and drink. In the first case, when we found oro-lingual dyskinesia due to amlodipine, we decreased the dosage of amlodipine from 10mg to 5mg, her oro-lingual dyskinesia was reduced in frequency and amplitude.
Discussion: The mechanism of oro-lingual dyskinesia by amlodipine is unknown. Some calcium-channel blocker affects dopaminergic neurotransmission, and this action may account for an affect on abnormal movements. In favor of this hypothesis there are reports of akathesia and parkinsonism as a side effect of diltiazem, flunarizine and cinnarizine. Thus chronic use of these agents may lead to an oro-lingual dyskinesia. Whatever the mechanisms are, these cases suggests an association between the amlodipine therapy and the development of oro-lingual dyskinesia.
Conclusion: Clinicians should be alert for this adverse drug reaction in elderly patients using this agent for a long time.
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