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promethazine-phenylephrine oral

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:

When these two medicines are taken together, your body may not absorb phenothiazines properly. The side effects of one or both medicines may increase and the benefits of phenothiazines may decrease.

What might happen:

The beneficial effects of phenothiazines may decrease along with an increased or decreased chance for side effects.

What you should do about this interaction:

If you experience increased constipation, drowsiness, dry mouth, dizziness, nasal congestion, or blurred vision, contact your doctor. It may be necessary to adjust the dose of your medicine.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.

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