Etrafon Forte and Dystonic reactions

Phenothiazines may cause acute, dose-related dystonic reactions secondary to central dopaminergic blockade. These reactions are characterized by spastic contraction of discrete muscle groups and may include torticollis, opisthotonos, carpopedal spasm, trismus, difficulty swallowing, perioral spasms with protrusion of the tongue, and oculogyric crisis. Onset is usually within 24 to 96 hours following initiation of therapy or an increase in dosage. Risk factors include young age, male gender, use of high-potency agents (e.g., fluphenazine, perphenazine, trifluoperazine), high dosages, and IM administration. Therapy with phenothiazines should be administered cautiously in patients, particularly children, with hypocalcemia or severe dehydration, since these patients may be more susceptible to dystonic reactions. Most symptoms subside within a few hours and are almost always reversible within 24 to 48 hours following withdrawal of therapy. However, severe reactions such as laryngospasm may be life-threatening and require appropriate supportive therapy. Parenteral administration of an anticholinergic antiparkinsonian agent (e.g., benztropine, trihexyphenidyl) or diphenhydramine usually produces a prompt response and may be given orally for short-term maintenance to prevent recurrence of symptoms if phenothiazine therapy must be continued.