promethazine and codeine, Phenergan with Codeine

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Pharmacy Author:

Omudhome Ogbru, PharmD

Omudhome Ogbru, PharmD

Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

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Medical and Pharmacy Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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GENERIC NAME: promethazine and codeine

BRAND NAME: (Phenergan with Codeine: This brand no longer is available in the U.S.)

DRUG CLASS AND MECHANISM: Promethazine is in a class of drugs called phenothiazines which also includes chlorpromazine (Thorazine) and trifluoperazine (Stelazine); however, unlike the other drugs in this class, promethazine is not used as an anti-psychotic but rather as an anti-histamine, sedative, antiemetic (anti-nausea), and cough suppressant.

Cells in the body release histamine during several types of allergic reactions. When histamine binds to its receptors on other cells, it stimulates changes within the cells that lead to release of other chemicals that cause sneezing, itching, and increased mucus production. Antihistamines such as promethazine compete with histamine for one of the receptors for histamine (the H1 receptor) on cells; however, when antihistamines bind to the receptors they do not stimulate the cells. Instead, they prevent histamine from binding and stimulating the cells. Promethazine also blocks the action of acetylcholine, a neurotransmitter that nerves use to communicate with one another, on its receptors (anticholinergic effect), and this may explain its benefit in reducing the nausea of motion sickness. It is used as a sedative because it causes drowsiness as a side effect. The cough suppressant effects may be due to is anticholinergic effects.

Codeine is a weak narcotic pain-reliever and cough suppressant similar to morphine and hydrocodone. In fact, a small amount of codeine is converted to morphine in the body. The precise mechanism of action of codeine is not known; however, like morphine, codeine binds to narcotic receptors in the brain (opioid receptors) that are important for transmitting the sensation of pain throughout the body and brain. Codeine increases tolerance to pain and decreases discomfort, but the pain still is apparent to the patient. In addition to reducing pain, codeine also causes sedation (drowsiness) and depresses breathing. The FDA approved promethazine and codeine in January 1952.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Syrup: 6.25mg of promethazine and 10mg of codeine per teaspoonful.

STORAGE: Promethazine and codeine should be stored at room temperature, 15-25 C (59-77 F) in a tightly closed container protected from light.

PRESCRIBED FOR: Promethazine and codeine is used for the treatment of cough and cold symptoms,

DOSING: The usual adult dose is one teaspoonful every 4 to 6 hours as needed. The maximum dose is two tablespoons daily.

DRUG INTERACTIONS: Excessive sedation may occur when promethazine and codeine is combined with other medications that cause sedation. Such drugs include ethanol, barbiturates, anti-anxiety medications, sedatives, other phenothiazines, and narcotic pain medications.

Promethazine should not be taken with any of the monoamine oxidase (MAO) inhibitor class of antidepressants, for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), and procarbazine (Matulane), because of the increased risk of extrapyramidal symptoms (EPS) - uncontrollable movement disorders.

Excessive anti-cholinergic effects (described below) can occur when promethazine is used with other antihistamines, for example, diphenhydramine (Benadryl), some phenothiazines, for example, thioridazine (Mellaril), some tricyclic antidepressants, for example, amitriptyline (Elavil, Endep), clozapine (Clozaril), cyclobenzaprine (Flexeril), and disopyramide (Norpace).

There may be an increase in the risk of certain neurologic reactions that affect movement of muscles (EPS, see below) when promethazine is combined with medicines that also cause EPS. Such drugs include antipsychotics, metoclopramide (Reglan), and amoxapine (Asendin).

Promethazine should not be used with propylthiouracil (PTU) due to the increased risk of low white blood cell counts and increased risk of infections. The reason for this interaction is not known.

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