Skip to content
My WebMD Sign In, Sign Up
Ditropan

Interactions

Select Antipsychotics;Select Phenothiazines/Anticholinergics

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

These medicines may be prescribed together to prevent or treat side effects from your antipsychotic or phenothiazine medicine. In other situations, the combination may increase the likelihood of medicine side effects.

What might happen:

Muscle spasm or tremors due to the antipsychotic or phenothiazine medicine may get better with this combination. Side effects such as dizziness, dry mouth, sedation, blurred vision or constipation may start or get worse with the combination.

What you should do about this interaction:

If you experience increased constipation, drowsiness, dry mouth, dizziness, or blurred vision, contact your doctor. If you become confused, feel restless/agitated, or have difficulty urinating, let your doctor know right away. It may be necessary to discontinue or adjust the dose of one or both medicines.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

References:

1.Gershon S, Neubauer H, Sundland DM. Interaction between some anticholinergic agents and phenothiazines. Potentiation of phenothiazine sedation and its antagonism. Clin Pharmacol Ther 1965 Nov-Dec;6(6):749-56.

2.Warnes H, Lehmann HE, Ban TA. Adynamic ileus during psychoactive medication: a report of three fatal and five severe cases. Can Med Assoc J 1967 Apr 15;96(15):1112-3.

3.Zelman S, Guillan R. Heat stroke in phenothiazine-treated patients: a report of three fatalities. Am J Psychiatry 1970 Jun;126(12):1787-90.

4.Singh MM, Smith JM. Reversal of some therapeutic effects of an antipsychotic agent by an antiparkinsonism drug. J Nerv Ment Dis 1973 Jul; 157(1):50-8.

5.Rivera-Calimlim L, Castaneda L, Lasagna L. Effects of mode of management on plasma chlorpromazine in psychiatric patients. Clin Pharmacol Ther 1973 Nov-Dec;14(6):978-86.

6.Loga S, Curry S, Lader M. Interactions of orphenadrine and phenobarbitone with chlorpromazine: plasma concentrations and effects in man. Br J Clin Pharmacol 1975 Jun;2(3):197-208.

7.Giordano J, Canter JW, Huang A. Fatal paralytic ileus complicating phenothiazine therapy. South Med J 1975 Mar;68(3):351-3.

8.DiMascio A. Toward a more rational use of antiparkinson drugs in psychiatry. Drug Ther 1971 Sep;1:23-9.

9.Rivera-Calimlim L, Nasrallah H, Strauss J, Lasagna L. Clinical response and plasma levels: effect of dose, dosage schedules, and drug interactions on plasma chlorpromazine levels. Am J Psychiatry 1976 Jun;133(6):646-52.

10.Kolakowska T, Wiles DH, Gelder MG, McNeilly AS. Clinical significance of plasma chlorpromazine levels. II. Plasma levels of the drug, some of its metabolites and prolactin in patients receiving long-term phenothiazine treatment. Psychopharmacology (Berl) 1976 Aug 26;49(1):101-7.

11.Chouinard G, Annable L, Cooper S. Antiparkinsonian drug administration and plasma levels of penfluridol, a new long-acting neuroleptic. Commun Psychopharmacol 1977;1(4):325-31.

12.Mann SC, Boger WP. Psychotropic drugs, summer heat and humidity, and hyperpyrexia: a danger restated. Am J Psychiatry 1978 Sep; 135(9):1097-1100.

13.Simpson GM, Cooper TB, Bark N, Sud I, Lee JH. Effect of antiparkinsonian medication on plasma levels of chlorpromazine. Arch Gen Psychiatry 1980 Feb;37(2):205-8.

14.Rockland L, Cooper T, Schwartz F, Weber D, Sullivan T. Effects of trihexyphenidyl on plasma chlorpromazine in young schizophrenics. Can J Psychiatry 1990 Oct;35(7):604-7.

15.Benztropine mesylate tablet US prescribing information. Bayshore Pharmaceuticals LLC December, 2013.

Selected from data included with permission and copyrighted by First Databank, Inc. This copyrighted material has been downloaded from a licensed data provider and is not for distribution, expect as may be authorized by the applicable terms of use.

CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.

More about Drugs and Medications

URAC: Accredited Health Web Site HONcode Seal AdChoices