Promethazine HCl

A to Z Drug Facts

 Action Competitively antagonizes histamine at H₁ receptor sites. Produces sedative and antiemetic effects.

 Indications

Oral/Rectal: Temporary relief of runny nose and sneezing caused by common cold; symptomatic relief of perennial and seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, allergic and nonallergic pruritic symptoms, mild, uncomplicated skin manifestations of urticaria, and angioedema; amelioration of allergic reactions to blood or plasma; treatment of dermographism; adjunctive therapy in anaphylactic reactions; preoperative, postoperative or obstetric sedation; prevention and control of nausea and vomiting associated with certain types of anesthesia and surgery; adjunctive therapy to analgesics for postoperative pain; sedation and relief of apprehension; induction of light sleep; active and prophylactic treatment of motion sickness; antiemetic therapy in postoperative patients.

Parenteral: Treatment of motion sickness; prevention and control of nausea and vomiting associated with anesthesia and surgery; allergic reactions.

IV: Adjunct to anesthesia and analgesia with reduced amounts of meperidine or other narcotic analgesics in special surgical situations (eg, repeated bronchoscopy, ophthalmic surgery, poor-risk patients).

 Contraindications Hypersensitivity to antihistamines; narrow-angle glaucoma; stenosing peptic ulcer; symptomatic prostatic hypertrophy; asthmatic attack; bladder neck obstruction; pyloroduodenal obstruction; comatose patients; CNS depression from barbiturates, general anesthetics, tranquilizers, alcohol, narcotics, or narcotic analgesics; previous phenothiazine idiosyncrasy, jaundice or bone marrow depression; acutely ill or dehydrated children; intra-arterial injection; nursing mothers; MAOI use.

 Route/Dosage

Allergy

Adults and Children over 2 yr: PO/PR 25 mg at bedtime; 12.5 mg before meals and at bedtime may be given if necessary. Single 25 mg doses at bedtime or 6.25 to 12.5 mg tid will usually suffice.

Adults: IM/IV 25 mg; may repeat dose within 2 hr if needed.

Children at least 2 yr: IM/IV Do not exceed 50% the adult dose.

Motion Sickness

Adults: PO 25 mg bid with initial dose taken 30 min to 1 hr before travel and repeated in 8 to 12 hr if needed. Thereafter 25 mg on rising and before evening meal.

Children over 2 yr: PO/PR 12.5 to 25 mg bid.

Nausea and Vomiting

Adults: PO/PR 25 mg. Repeat doses of 12.5 to 25 mg prn q 4 to 6 hr. IM/IV 12.5 to 25 mg not more than q 4 hr.

Children over 2 yr: PO/PR 1 mg/kg q 4 to 6 hr prn.

Prophylaxis of Nausea and Vomiting

Adults: PO/PR 25 mg q 4 to 6 hr prn.

Children over 2 yr: PO/PR 1 mg/kg q 4 to 6 hr prn.

Nighttime Sedation

Adults: PO/PR/IM/IV 25 to 50 mg.

Children over 2 yr: PO/PR/IM/IV 12.5 to 25 mg.

Preoperative Sedation

Adults: PO/PR 25 to 50 mg night before surgery. IM/IV 25 to 50 mg night before surgery.

Children over 2 yr: PO/PR 1 mg/kg.

Children 2 to 12 yr: IM/IV 1 mg/kg.

Postoperative Sedation and Adjunctive Use with Analgesics

Adults: PO/PR/IM/IV 25 to 50 mg.

Children over 2 yr: PO/PR/IM/IV 12.5 to 25 mg.

Sedation During Labor

Adults: IM/IV 50 mg in early stages of labor. When labor is established, 25 to 75 mg with reduced dose of narcotic (max total dose, 100 mg/24 hr).

 Interactions

Anticholinergics: May decrease action of promethazine.

Barbiturate anesthetics: Risk of neuromuscular excitation and hypotension may increase.

CNS depressants (eg, alcohol, narcotics): May have additive CNS depressant effects.

MAO inhibitors: May prolong and intensify anticholinergic effects; may cause hypotension and extrapyramidal effects.

Metrizamide: May increase risk of seizure.

 Lab Test Interferences Diagnostic pregnancy tests based on immunologic reactions between hCG and anti-hCG may result in false-negative or false-positive interpretations. Following interferences also have occurred: increased serum cholesterol, blood glucose, spinal fluid protein, and urinary urobilinogen concentrations; decreased protein-bound iodine; false positive urine bilirubin tests; interference with urinary ketone and steroid determinations; false-positive phenylketonuria test results.

 Adverse Reactions

CARDIOVASCULAR: Orthostatic hypotension; palpitations; bradycardia; tachycardia; reflex tachycardia; extrasystoles. CNS: Drowsiness; sedation; dizziness; faintness; disturbed coordination; extrapyramidal effects (usually dose related and include three forms: pseudoparkinsonism, akathisia, dystonias); tardive dyskinesia; adverse behavioral effects.EENT: Blurred vision; nasal stuffiness; dry nose; dry or sore throat. GI: Epigastric distress; dry mouth; nausea; vomiting; diarrhea; constipation. GU: Urinary retention/frequency. HEMATOLOGIC: Hemolytic anemia; thrombocytopenia; agranulocytosis. METABOLIC: Increased appetite, weight gain. RESPIRATORY: Thickening of bronchial secretions; chest tightness; wheezing; respiratory depression. OTHER: Hypersensitivity reactions; photosensitivity; elevated prolactin levels; neuroleptic malignant syndrome.

 Precautions

Pregnancy: Category C. Do not use during third trimester. Lactation: Undetermined. Contraindicated in nursing mothers. Children: Contraindicated in children who are acutely ill or dehydrated. Tablets and suppositories are not recommended in children less than 2 yr. Antihistamines may diminish mental alertness and may produce paradoxical excitation. Administer IV form with caution. Not recommended for treatment of uncomplicated vomiting in children; use only when vomiting is prolonged and of unknown cause. Extrapyramidal symptoms that can occur secondary to IV use may be confused with CNS signs of undiagnosed primary disease (eg, encephalopathy, Reye syndrome). Avoid use in children with history of sleep apnea, family history of Sudden Infant Death Syndrome (SIDS) or hepatic diseases, and in children with Reye syndrome. Elderly: Greater likelihood of dizziness, excessive sedation, syncope, toxic confusional states, and hypotension in patients over 60 yr. Dosage reduction may be required. Special risk patients: Use drug with caution in patients with predisposition to urinary retention, history of bronchial asthma, IOP, hyperthyroidism, sleep apnea, cardiovascular disease or hypertension, bone marrow depression, liver dysfunction, ulcer disease, or respiratory impairment. Hypersensitivity: Hypersensitivity may occur. Have 1:1000 epinephrine immediately available. Lower seizure threshold: Drug may lower seizure threshold; use drug with caution in people with known seizure disorders or when giving in combination with narcotics or local anesthetics that may alter seizure control. Respiratory disease: Drug is generally not recommended to treat lower respiratory tract symptoms including asthma. Skin test procedures: May prevent or diminish positive reactions to dermal reactivity indicators. If possible, discontinue 4 days prior to skin test.

 Administration/Storage

• Give oral form with food if GI upset occurs.
• When administering drug parenterally, preferred route is IM injection.
• If drug must be administered IV, use caution; do not inject directly into vein and inject through appropriate site in IV tubing. Promethazine may be mixed with meperidine in same syringe.
• Do not exceed IV concentration of 25 mg/mL and do not exceed IV rate of 25 mg/min.
• Do not administer SC or intra-arterially.
• Dose of barbiturates must be reduced by ½ and of narcotics by ¼ to ½ when using this drug concomitantly.
• Avoid use of this drug in cases of vomiting of unknown origin.
• Discontinue drug 4 days before skin testing procedures.
• Store suppositories in refrigerator and use while cold and firm.
• Store oral dosage form at room temperature in tightly closed, light-resistant container.
• Store parenteral form at room temperature, protected from light. Do not freeze.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note presence of glaucoma, ulcer disease, urinary retention, hypertension, seizure disorder, bone marrow depression, history of bronchial asthma, hyperthyroidism, cardiovascular disease, or liver dysfunction.
• Monitor for possible increased blood glucose.
• In children, check for history of sleep apnea, Reye syndrome, hepatic disease, or family history of SIDS.
• Observe for sedation, fatigue, insomnia, dry mouth, sore throat, thickening of mucus, unusual bleeding, or nervousness, and report to health care provider.

 Patient/Family Education

• Instruct patient using drug for motion sickness to take drug 30 min to 1 hr before travel.
• Teach patient to store suppositories in refrigerator and to use while cold and firm.
• Advise patient to notify all health care professionals of this drug therapy.
• Inform patient that drug may cause dryness of mouth, nose, or throat and to notify health care provider if this dryness continues for more than 2 wk.
• Instruct patient to report the following symptoms to health care provider: sore throat, thickening of mucus, fever, unusual bleeding, drowsiness, unusual weakness.
• Advise patient to take sips of water frequently or to suck on ice chips or sugarless candy, or chew sugarless gum if dry mouth occurs.
• Caution patient to avoid sudden position changes to prevent orthostatic hypotension.
• Instruct patient to avoid intake of alcoholic beverages and other CNS depressants.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.
• Caution patient to avoid exposure to sunlight and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts