ASK DIS: Acute Dystonic Reaction : Treatment

An acute dystonic reaction, usually transient, is a recognized complication of the dopamine receptor-blocking drugs, such as the antipsychotics (eg, haloperidol, chlorpromazine) and antiemetics (eg, phenothiazines, metoclopramide)
Dystonic reactions also can occur with levodopa, anticonvulsants, antidepressants (eg, selective serotonin reuptake inhibitors), and ergots.

Treatment

The offending drug should be discontinued.
Treatment of acute dystonia with antihistamine or anticholinergic medications is usually rapidly effective

Diphenhydramine

IV diphenhydramine (1 to 2 mg/kg per dose, maximum dose 50 mg) is used most frequently
Diphenhydramine may also be given intramuscularly but the onset of action is delayed compared with intravonicenous administration.
Typically results in resolution of an acute dystonic reaction within minutes.
Muscle relaxation begins within 30 minutes and but may not complete for 90 minutes when the antidote is given as IM or Oral
Intravenous administration is preferred over oral administration for initiation of treatment because patients may have difficulty swallowing.
Parenteral administration is required for life-threatening dystonia with associated laryngospasm or stridor
Once the acute dystonic reaction is treated, diphenhydramine is given orally (1.25 mg/kg per dose) every six hours for one to two days to prevent recurrence or 12.5-50mg TDS-QID for 3 days
In some cases, however, a single dose of oral diphenhydramine or trihexyphenidyl suffices.

Benzodiazepams

Some recommend using diazepam for patients with dystonic reactions refractory to anticholinergic therapy or when such therapy is contraindicated
Diazepam and lorazepam are favoured because of their longer duration of action
IV diazepam can be given in 5-mg increment every 5 minutes as needed for reversal
lorazepam 1 to 2 mg IV in adults; 0.05 mg/kg IV in children or 2mg every 5 minute as needed

Others

Antihistamine, benzodiazepines, beta-adrenergic antagonists (propranolol), beta-adrenergic agonists (clonidine), or dopamine agonists (amantadine) may also be used
amantadine (100 mg orally twice or three times daily in adults), or biperiden (2 mg orally in adults). At least two controlled studies have shown amantadine to be as effective as anticholinergic therapy, with fewer side effects
Propranolol (20 to 40 mg initial dose) reduces involuntary movements in akathisia, but does not reduce anxiety
A randomized trial of 13 patients with acute akathisia from antipsychotic medications reported a benefit from trazodone (100 mg/day orally in adults)
Patients treated with dopamine receptor-blocking agents occasionally develop persistent tardive dystonia after the offending drug is stopped.
If no spontaneous improvement occurs, they may respond to trials of muscle relaxants, anticholinergic drugs, and tetrabenazine

References:

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