Haloperidol Antacids

Dicyclomine (Bentyl) [Anrimuscarinic, GI Anrispasmodic/ Anticholinergic] Uses Functional IBS Action Smooth-muscle relaxant Dose Adults. 20 mg PO qid T to 160 mg/d max or 20 mg EM q6h, 80 mg/d - qid then T to 160 mg/d, max 2 wk Feds. Infants >6 mo 5mg/dose tid-qid Children 10 mg/dose tid-qid Caution [B, -] Contra Infants <6 mo, NAG, MyG, severe UC, BOO Disp Caps, tabs, syrup, inj SE Anticholinergic SEs may limit dose Interactions T Anticholinergic effects W/ anticholinergics, antihistamines, amantadine, MAOIs, TCAs, phenothiazides T effects OF atenolol, digoxin X effects H7 antacids X effects OF haloperidol, ketoconazole, levodopa, phenothiazines EMS Avoid procainamide usage, may T adverse effects may T effects of digoxin, monitor... 

Antacids containing aluminium/magnesium hydroxide or magnesium trisilicate can reduce the serum levels of chlorpromazine which would be expected to reduce the therapeutic response. Sucralfate and an aluminium/magnesium hydroxide antacid can reduce the absorption of sulpiride. In vitro studies suggest that this interaction may possibly also occur with other antacids and phe-nothiazines. There seem to be no clinical studies or reports confirming the anecdotal evidence of a possible reduction in the effects of haloperidol by antacids. 

In 1982 a questioner in a letter asked whether haloperidol interaets with antaeids because he had a patient responding well to treatment with haloperidol who had begun to deteriorate when Amphojel (aluminium hydroxide) was added. In a written answer it was stated that there are no reports of this interaction but several clinicians had said that based on clinical impressions oral haloperidol and antacids should not be given together. 

Activated charcoal causes a fall in olanzapine levels and venlafax-ine moderately raise olanzapine levels. Additive dopaminergic effects have been seen in one patient taking olanzapine and haloperidoL Olanzapine appears not to interact to a clinically relevant extent with aluminium/magnesium hydroxide antacids, ci-metidine or diazepam. However, excessive sedation and hypotension may occur with parenteral benzodiazepines and intramuscular olanzapine. 

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