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Back to Drug index
Name: Promethazine hydrochloride
Pregnancy Category C
Drug classes
- Antiemetic
- Phenothiazine
- Dopaminergic blocking drug
- Antihistamine
- Antimotion sickness drug
- Sedative
Therapeutic actions
Selectively blocks H1 receptors, diminishing the effects of
histamine on cells of the upper respiratory tract and eyes and
decreasing
the sneezing, mucus production, itching, and tearing that accompany
allergic reactions in sensitized people exposed to antigens; blocks cholinergic receptors in the vomiting center that are believed to
mediate
the nausea and vomiting caused by gastric irritation, by input from
the
vestibular apparatus (motion sickness, nausea associated with
vestibular
neuritis), and by input from the chemoreceptor trigger zone (drug- and
radiation-induced emesis); depresses the reticular activating system,
including the parts of the brain involved with wakefulness.
Indications
Symptomatic relief of symptoms associated with perennial and seasonal
allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis; mild,
uncomplicated urticaria and angioedema; amelioration of allergic
reactions to blood or plasma; dermatographism, adjunctive therapy
(with
epinephrine and other measures) in anaphylactic reactions
Treatment and prevention of motion sickness; prevention and control of
nausea and vomiting associated with anesthesia and surgery
Preoperative, postoperative, or obstetric sedation
Adjunct to analgesics to control postoperative pain
Adjunctive IV therapy with reduced amounts of meperidine or other
narcotic analgesics in special surgical situations, such as repeated
bronchoscopy, ophthalmic surgery, or in poor-risk patients
Contraindications/cautions
Contraindicated in the presence of hypersensitivity to antihistamines
or
phenothiazines, coma or severe CNS depression, bone marrow depression,
vomiting of unknown cause, concomitant therapy with MAOIs, lactation
(lactation may be inhibited).
Use caution in the presence of lower respiratory tract disorders (drug
may cause thickening of secretions and impair expectoration),
glaucoma,
prostatic hypertrophy, cardiovascular disease or hypertension, breast
cancer, thyrotoxicosis, pregnancy (jaundice and extrapyramidal
symptoms
have been reported in infants whose mothers received phenothiazines
during pregnancy; drug may inhibit platelet aggregation in neonate if
taken by mother within 2 wk of delivery), children (antihistamine
overdosage may cause hallucinations, convulsions, and death), a child
with a history of sleep apnea, a family history of sudden infant death
syndrome, or Reye's syndrome (drug may mask the symptoms of Reye's
syndrome and contribute to its development), the elderly (more likely
to
cause dizziness, sedation, syncope, toxic confusional states,
hypotension, and extrapyramidal effects in the elderly).
Adverse effects
- CNS: Dizziness, drowsiness, poor coordination, confusion,
restlessness,
excitation, convulsions, tremors, headache, blurred vision, diplopia,
vertigo, tinnitus
- GI: Epigastric distress, nausea, vomiting, diarrhea, constipation
- CV: Hypotension, palpitations, bradycardia, tachycardia, extrasystoles
- Respiratory: Thickening of bronchial secretions; chest tightness; dry
mouth, nose, and throat; respiratory depression; suppression of cough
reflex, potential for aspiration
- Hematologic: Hemolytic anemia, hypoplastic anemia, thrombocytopenia,
leukopenia, agranulocytosis, pancytopenia
- GU: Urinary frequency, dysuria, urinary retention, decreased libido,
impotence
- Dermatologic: Urticaria, rash, photosensitivity, chills
- Other: Tingling, heaviness and wetness of the hands
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