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fluphenazine injection


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 process the medicines differently.

What might happen:

The effects of your barbiturate may increase and cause increased drowsiness, slowed breathing, and a decrease in blood pressure. The effects of your phenothiazine may decrease and it may not work as well.

What you should do about this interaction:

If you experience excessive drowsiness, slowed breathing, weakness, fatigue, or dizziness, contact your doctor. It may be necessary to monitor your blood pressure and breathing rate. Let your doctor know if your symptoms worsen. Your doctor may need to adjust the dose of your 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.


1.Phenergan (promethazine hydrochloride) US prescribing information. Baxter Healthcare Corporation December, 2006.
2.Chlorpromazine hydrochloride US prescribing information. Baxter Healthcare Corporation October, 2006.
3.Hatanaka T, Negishi S, Katayama K, Kakemi M, Koizumi T. The pharmacodynamic and pharmacokinetic interaction of pentobarbital and chlorpromazine in rats. J Pharmacobiodyn 1988 Jan;11(1):47-52.
4.Hatanaka T, Sato S, Endoh M, Katayama K, Kakemi M, Koizumi T. Effect of chlorpromazine on the pharmacokinetics and pharmacodynamics of pentobarbital in rats. J Pharmacobiodyn 1988 Jan;11(1):18-30.
5.Forrest FM, Forrest IS, Serra MT. Modification of chlorpromazine metabolism by some other drugs frequently administered to psychiatric patients. Biol Psychiatry 1970 Jan;2(1):53-8.
6.Curry SH, Marshall JH, Davis JM, Janowsky DS. Chlorpromazine plasma levels and effects. Arch Gen Psychiatry 1970 Apr;22(4):289-96.
7.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.
8.Gay PE, Madsen JA. Interaction between phenobarbital and thioridazine. Neurology 1983 Dec;33(12):1631-2.
9.Ellenor GL, Musa MN, Beuthin FC. Phenobarbital--thioridazine interaction in man. Res Commun Chem Pathol Pharmacol 1978 Jul;21(1):185-8.
10.Linnoila M, Viukari M, Vaisanen K, Auvinen J. Effect of anticonvulsants on plasma haloperidol and thioridazine levels. Am J Psychiatry 1980 Jul; 137(7):819-21.

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