Dystonic activity

BAYK8644 is a DHP with Ca2+ channel activating properties. Although some therapeutic effects can be envisaged for such drugs (such as stimulation of glucose-dependent insulin secretion, positive inotropy), severe side effects are also predicted from animal studies (dystonic neurobehavioral syndrome, hypertension, arrhythmias), which currently prevents their clinical development. 

A combined administration of metoclopramide and anticholinergic agent to reduce dystonic reactions of metoclopramide, did not diminish antiemetic efficacy in dogs [117], Thus, the inhibitory effect on GI smooth muscle by cholinergic blockade had no significant impact on antiemetic activity of metoclopramide. 

Infrequently, SSRIs produce dystonic reactions, which are intense mnscle spasms nsnally of the face and neck. They may cause akathisia, a restless inability to sit still. Dystonic reactions and akathisia are more commonly side effects of the dopamine-blocking antipsychotics. It is believed that SSRIs prodnce these effects because increasing 5HT activity tends to decrease dopamine. When these side effects occur, the SSRI should be switched to another antidepressant. 

Propranolol and gabapentin are both effective in essential tremor. However, pindolol, which has substantial partial agonist activity, can cause tremor (130), and gabapentin can occasionally cause reversible movement disorders. A patient who developed dystonic movements after the combined use of gabapentin and propranolol has been described (131). 

A full-term neonate was accidentally given carboprost 250 pg intramuscularly in an error for hepatitis vaccine. Within 15 minutes, he became tachypneic and hypertensive and then developed bronchospasm and dystonic movements and/or seizure activity in the arms. He was hyperthermic and had diarrhea. He recovered within 18 hours. 

All basic and advanced life-support measures should be implemented. Gastric decontamination should be performed. Butyrophenones are readily absorbed by activated charcoal. Aggressive supportive care should be instituted. Dystonic reactions respond well to intravenous benztropine or diphenhydramine. Oral therapy with diphenhydramine or benztropine should be continued for 2 days to prevent recurrence of the dystonic reaction. For patients suffering from neuroleptic malignant syndrome, a potentially fatal condition associated with the administration of antipsychotic drugs, dantrolene sodium, and bromocriptine have been used in conjunction with cooling and other supportive measures. Arrhythmias should be treated with lidocaine or phenytoin. Diazepam is the drug of choice for seizures phenytoin is used to prevent recurrence. Hemodialysis and hemoperfu-sion have not been shown to be effective. 

A retrospective case analysis of 55 paediatric emergency department patients reported presentations due to drug-induced dystonic reactions with FGAs (haloperidol, chlorpromazine), SGAs (risperidone) and antiemetics with anti-dopaminergic activity (metoclopramide) [42 ]. 

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