General
Drugs having anticholinergic properties should be used with caution in patients with narrow-angle glaucoma, prostatic hypertrophy, stenosing peptic ulcer, pyloroduodenal obstruction, and bladder-neck obstruction.
Promethazine hydrochloride injection should be used cautiously in persons with cardiovascular disease or impairment of liver function.
Information for Patients
Patients should be advised of the risk of respiratory depression, including potentially fatal respiratory depression in children less than 2 years of age (see WARNINGS - Respiratory Depression).
Patients should be advised of the risk of severe tissue injury, including gangrene (see WARNINGS - Severe Tissue Injury, Including Gangrene). Patients should be advised to immediately report persistent or worsening pain or burning at the injection site.
Promethazine hydrochloride injection may cause marked drowsiness or impair the mental or physical abilities required for the performance of potentially hazardous tasks, such as driving a vehicle or operating machinery. Pediatric patients should be supervised to avoid potential harm in bike riding or in other hazardous activities. The concomitant use of alcohol, sedative/hypnotics (including barbiturates), general anesthetics, narcotics, narcotic analgesics, tricyclic antidepressants, and tranquilizers may enhance impairment (see WARNINGS - CNS Depression and PRECAUTIONS - Drug Interactions).
Patients should be advised to report any involuntary muscle movements (see ADVERSE REACTIONS - Paradoxical Reactions).
Patients should be advised to avoid prolonged exposure to the sun (see ADVERSE REACTIONS - Dermatologic).
Drug Interactions
CNS Depressants
Promethazine hydrochloride injection may increase, prolong, or intensify the sedative action of central-nervous-system depressants, such as alcohol, sedative/hypnotics (including barbiturates), general anesthetics, narcotics, narcotic analgesics, tricyclic antidepressants, and tranquilizers; therefore, such agents should be avoided or administered in reduced dosage to patients receiving promethazine hydrochloride. When given concomitantly with promethazine hydrochloride injection, the dose of barbiturates should be reduced by at least one-half, and the dose of narcotics should be reduced by one-quarter to one-half. Dosage must be individualized. Excessive amounts of promethazine hydrochloride injection relative to a narcotic may lead to restlessness and motor hyperactivity in the patient with pain; these symptoms usually disappear with adequate control of the pain.
Epinephrine
Because of the potential for promethazine hydrochloride to reverse epinephrine’s vasopressor effect, epinephrine should NOT be used to treat hypotension associated with promethazine hydrochloride injection overdose.
Anticholinergics
Concomitant use of other agents with anticholinergic properties should be undertaken with caution.
Monoamine Oxidase (MAO) Inhibitors
Drug interactions, including an increased incidence of extrapyramidal effects, have been reported when some MAO Inhibitors and phenothiazines are used concomitantly. This possibility should be considered with promethazine hydrochloride injection.
Drug/Laboratory Test Interactions
The following laboratory tests may be affected in patients who are receiving therapy with promethazine hydrochloride injection:
Pregnancy Tests
Diagnostic pregnancy tests based on immunological reactions between HCG and anti-HCG may result in false-negative or false-positive interpretations.
Glucose Tolerance Test
An increase in blood glucose has been reported in patients receiving promethazine hydrochloride.
Carcinogenesis, Mutagenesis and Impairment of Fertility
Long-term animal studies have not been performed to assess the carcinogenic potential of promethazine hydrochloride injection, nor are there other animal or human data concerning carcinogenicity, mutagenicity, or impairment of fertility. Promethazine hydrochloride injection was nonmutagenic in the Salmonella test system of Ames.
Pregnancy
Teratogenic Effects—Pregnancy Category C
Teratogenic effects have not been demonstrated in rat-feeding studies at doses of 6.25 and 12.5 mg/kg (approximately 2.1 and 4.2 times the maximum recommended human daily dose) of promethazine hydrochloride injection. Daily doses of 25 mg/kg intraperitoneally have been found to produce fetal mortality in rats.
There are no adequate and well-controlled studies of promethazine hydrochloride injection in pregnant women. Because animal reproduction studies are not always predictive of human response, promethazine hydrochloride injection should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Adequate studies to determine the action of the drug on parturition, lactation and development of the animal neonate have not been conducted.
Nonteratogenic Effects
Promethazine hydrochloride injection administered to a pregnant woman within two weeks of delivery may inhibit platelet aggregation in the newborn.
Labor and Delivery
Promethazine hydrochloride injection may be used alone or as an adjunct to narcotic analgesics during labor (see DOSAGE AND ADMINISTRATION). Limited data suggest that use of promethazine hydrochloride injection during labor and delivery does not have an appreciable effect on the duration of labor or delivery and does not increase the risk of need for intervention in the newborn. The effect on later growth and development of the newborn is unknown. (See also Pregnancy - Nonteratogenic Effects.)
Nursing Mothers
It is not known whether promethazine hydrochloride injection is excreted in human milk. Because many drugs are excreted in human milk, and because of the potential for serious adverse reactions in nursing infants from promethazine hydrochloride injection, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Pediatric Use
Promethazine hydrochloride injection is contraindicated for use in pediatric patients less than 2 years of age, because of the potential for fatal respiratory depression. Promethazine hydrochloride injection should be used with caution in pediatric patients 2 years of age and older (see WARNINGS - Respiratory Depression).
Antiemetics are not recommended for treatment of uncomplicated vomiting in pediatric patients, and their use should be limited to prolonged vomiting of known etiology. The extrapyramidal symptoms which can occur secondary to promethazine hydrochloride injection administration may be confused with the CNS signs of undiagnosed primary disease, e.g. encephalopathy or Reye's syndrome. The use of promethazine hydrochloride injection should be avoided in pediatric patients whose signs and symptoms may suggest Reye's syndrome or other hepatic diseases.
Excessively large dosages of antihistamines, including promethazine hydrochloride injection, in pediatric patients may cause sudden death (see OVERDOSAGE). Hallucinations and convulsions have occurred with therapeutic doses and overdoses of promethazine hydrochloride injection in pediatric patients. In pediatric patients who are acutely ill associated with dehydration, there is an increased susceptibility to dystonias with the use of promethazine hydrochloride injection.
Geriatric Use (patients approximately 60 years or older)
Since therapeutic requirements for sedative drugs tend to be less in geriatric patients, the dosage should be reduced for these patients.