[Parkinson syndrome, a possible adverse effect of calcium inhibitors]

The effects of calcium inhibitors are not limited to the muscles and may affect other systems and cause varied side effects. Two cases of Parkinsonian syndrome occurring after starting therapy with calcium inhibitors (verapamil in one case and diltiazem in the other) are reported. Complete regression of the symptoms after withdrawing the drugs was strongly in favour of a causal relationship. The condition could be due to inhibition of the calcium channels in the central nervous system disturbing neurotransmission. This seems to be a rare side effect as there have only been three other reported cases of secondary extrapyramidal syndromes in the literature. However, a Parkinsonian syndrome is very invalidating and clinicians using this family of drugs should be aware of this possible complication.