Medications and Drugs
Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD
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: 10 mg of promethazine and 6.25 mg 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).
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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