Drug Interactions between Colfed-A and haloperidol

Using haloperidol together with chlorpheniramine may increase side effects such as drowsiness, blurred vision, dry mouth, heat intolerance, flushing, decreased sweating, difficulty urinating, abdominal cramping, constipation, irregular heartbeat, confusion, and memory problems. Side effects may be more likely to occur in the elderly or those with a debilitating condition. You should avoid or limit the use of alcohol while being treated with these medications. Also avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medications affect you. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Butyrophenone neuroleptics may antagonize the pharmacologic effects of amphetamine, amphetamine derivatives, and other centrally-acting sympathomimetic agents (i.e., CNS stimulants). Conversely, these agents may diminish the neuroleptic efficacy of butyrophenones. The exact mechanism of interaction is unknown but may involve opposing effects on dopaminergic activity. Several clinical studies have demonstrated the reduction or lack of effect of amphetamines on weight loss in obese psychiatric patients treated with haloperidol and other neuroleptic agents, most notably chlorpromazine. In one of these studies, dextroamphetamine also had no effect on sleep patterns. Another study found haloperidol to inhibit amphetamine-induced symptoms and may be useful in amphetamine intoxication. As for the reverse interaction, it is uncertain whether CNS stimulants actually antagonize the neuroleptic effect of butyrophenones, since CNS stimulants alone have been reported to cause or aggravate preexisting psychotic symptoms. There has also been a report of acute dystonia occurring in two normal, healthy young women given haloperidol and dexamphetamine as part of a neuropharmacological study. The authors postulated that the reaction was due to a potentiation of dopamine release.

MANAGEMENT: Amphetamine, amphetamine derivatives, and other CNS stimulants should generally not be used, particularly for weight reduction, in patients treated with a butyrophenone neuroleptic agent.