Haloperidol Benzatropine

An 11-year-old boy developed acute dysuria and increased frequency accompanied by gross hematuria. He was taking fluoxetine, valproic acid, benzatropine, haloperidol, clonidine, trazodone, and nasal desmopressin. One week before presentation, risperidone had been introduced instead of haloperidol to improve behavioral control. The risperidone was discontinued and haloperidol resumed, and his symptoms resolved during the following week. 

Olanzapine versus chlorpromazine In 103 previously treatment-resistant patients with schizophrenia were given a prospective 6-week trial of 10-40 mg/day of haloperidol 84 failed to respond and were randomly assigned to a double-blind, 8-week, fixed-dose trial of either olanzapine 25 mg/day alone (n = 42) or chlorpromazine 1200 mg/day plus benzatropine mesylate 4 mg/day (n = 39) (51). There was no significant... 

The possibility of fatal intestinal dilatation, although very rare, warrants careful evaluation of persistent complaints of constipation, particularly in patients who also have vomiting and abdominal pain, distension, or tenderness (518). Acute intestinal pseudo-obstruction (Ogilvie s syndrome) has been reported in a patient taking haloperidol plus benzatropine (519). 

A 64-year-old woman started to take oral haloperidol 0.5 mg tds, and 3 days later was given intravenous benzatropine 2 mg for dystonia plus a second dose 1 hour later because she had not responded to the first dose. Her dystonia improved, but she started to develop abdominal distension and discomfort, and within the next 3-4 hours her whole abdomen had become significantly distended. Haloperidol and benzatropine were withdrawn and she was treated with hydration, nasogastric suction, a rectal tube, and frequent change of position. With this conservative therapy, her abdominal distension resolved completely in 24 hour. 

Acute extrapyramidal reactions occur more often after ingestion of high-potency drugs, such as haloperidol and fluphenazine these respond to parenteral benzatropine, but anticholinergic drugs should be used judiciously, so as not to worsen peripheral or central autonomic toxicity. Other serious, but less frequent, complications include paralytic ileus and hypothermia. Acute renal insufficiency has been very rarely reported, but is apparently reversible and can occur secondary to severe hypotension or other causes after acute ingestion (615). 

When paroxetine was introduced in a patient taking benzatropine and haloperidol, the circulating concentrations of benzatropine rose and delirium occurred (SEDA-22, 157) (1). 

Acute extrapyramidal reactions occur more often after ingestion of high-potency drugs, such as haloperidol and fluphenazine these respond to parenteral benzatropine, but anticholinergic drugs should be used judiciously, so as... 

Worsening parkinsonism was observed in two patients after treatment with olanzapine 5 mg/day (72). In contrast, coarse tremors induced by fluphenazine or haloperidol disappeared in three patients within days of the start of treatment with olanzapine (10 mg/day), without discontinuation or reduction in the dosage of fluphenazine or haloperidol (73). Olanzapine is active at muscarinic cholinergic receptors, which may account for the observed suppression of neuroleptic drug-induced tremor however, two of the three patients had been taking benzatropine, an antagonist at muscarinic acetylcholine receptors, with little tremor relief, suggesting that olanzapine could suppress tremor by means of an action other than muscarinic blockade. 

Eight patients deveioped deiirium when given fluoxetine, paroxetine or sertraline with benzatropine, in the presence of an antipsychotic (usually perphenazine or haloperidol). Other patients taking the combination remained symptom free. 

Other studies confirm that trihexyphenidyl and orphenadiine reduce the plasma levels and effects of chlorpromazine. In contrast to these reports, another found that trihexyphenidyl increased chlorpromazine levels by 41% in 20 young schizophrenics, but no clinical change was seen. The levels dropped again over the first 4 weeks of treatment. Some of the beneficial actions of haloperidol on social avoidance behaviour ate lost during concurrent treatment with benzatropine, but cognitive integrative function is unaffected. 

---