promethazine hydrochloride

Drug Name

Generic Name : promethazine hydrochloride

Brand Name: Phenadoz, Phenergan

Classification: Phenothiazine, Dopaminergic blocking agent, Antihistamine, Antiemetic, Anti-motion sickness drug, Sedative or hypnotic

Pregnancy Category C 

Dosage & Route

Available forms : Tablets—12.5, 25, 50 mg; syrup—6.25, 25 mg/5 mL; suppositories—12.5, 25, 50 mg; injection—25, 50 mg/mL

ADULTS
  • Allergy: Average dose is 25 mg PO or by rectal suppository, preferably at bedtime. If needed, 12.5 mg PO before meals and hs; 25 mg IM or IV for serious reactions. May repeat within 2 hr if needed at bedtime.
  • Motion sickness: 25 mg PO bid. Initial dose should be scheduled 30–60 min before travel; repeat in 8–12 hr if needed. Thereafter, give 25 mg on arising and before evening meal.
  • Nausea and vomiting: 25 mg PO; repeat doses of 12.5–25 mg as needed, q 4–6 hr. Give rectally or parenterally if oral dosage is not tolerated. 12.5–25 mg IM or IV, not to be repeated more frequently than q 4–6 hr.
  • Sedation: 25–50 mg PO, IM, or IV.
  • Preoperative use: 50 mg PO the night before, or 50 mg with an equal dose of meperidine and the required amount of belladonna alkaloid.
  • Postoperative sedation and adjunctive use with analgesics: 25–50 mg PO, IM, or IV.
  • Labor: 50 mg IM or IV in early stages. When labor is established, 25–75 mg with a reduced dose of opioid. May repeat once or twice at 4-hr intervals. Maximum dose within 24 hr is 100 mg.
PEDIATRIC PATIENTS > 2 YR
  • Allergy: 25 mg PO at bedtime or 6.25–12.5 mg tid.
  • Motion sickness: 12.5–25 mg PO or rectally bid.
  • Nausea and vomiting: 1 mg/kg IM q 4–6 hr as needed.
  • Sedation: 12.5–25 mg PO or 12.5–25 mg PO or PR at bedtime q 4–6 hr.
  • Preoperative use: 1 mg/kg PO in combination with an equal dose of meperidine and the required amount of an atropine-like drug.
  • Postoperative sedation and adjunctive use with analgesics: 1 mg/kg PO, IM, IV, or rectally.
Therapeutic actions
  • Promethazine, a phenothiazine derivative, blocks postsynaptic dopaminergic receptors in the brain and has a strong α-adrenergic blocking effect. It competitively binds to H1-receptors.
Indications
  • Symptomatic relief of 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 opioid analgesics in special surgical situations, such as repeated bronchoscopy, ophthalmic surgery, or in poor-risk patients
Adverse effects
  • CNS depression, paradoxical excitation in childn, dryness of mouth, blurring of vision, retention of urine, constipation, glaucoma, tachycardia, headache, hypotension, tinnitus.
Contraindications
  • Hypersensitivity, coma, porphyria, cardiac disease, hypokalaemia, intra-arterial or SC inj, neonates and young children, pregnancy, lactation.
Nursing considerations
Assessment
  • History: Hypersensitivity to antihistamines or phenothiazines, severe CNS depression, bone marrow depression, vomiting of unknown cause, concomitant therapy with MAOIs, lactation, lower respiratory tract disorders, glaucoma, prostatic hypertrophy, CV disease or hypertension, breast cancer, thyrotoxicosis, pregnancy, history of sleep apnea or a family history of SIDS, child with Reye’s syndrome
  • Physical: Weight, T; reflexes, orientation, IOP; P, BP, orthostatic BP; R, adventitious sounds; bowel sounds and normal output, liver evaluation; urinary output, prostate size; CBC; urinalysis; LFTs, renal and thyroid function tests
Interventions
  • BLACK BOX WARNING: Do not give tablets OR rectal suppositories to children < 2 yr.
  • Give IM injections deep into muscle.
  • Do not administer subcutaneously; tissue necrosis may occur.
  • WARNING: Do not administer intra-arterially; arteriospasm and gangrene of the limb may result.
  • WARNING: Reduce dosage of barbiturates given concurrently with promethazine by at least half; arrange for dosage reduction of opioid analgesics given concomitantly by one-fourth to one-half.
Teaching points
  • Take drug exactly as prescribed.
  • Avoid using alcohol.
  • Avoid driving or engaging in other dangerous activities if dizziness, drowsiness, or vision changes occur.
  • Avoid prolonged exposure to sun, or use a sunscreen or covering garments.
  • Maintain fluid intake, and use precautions against heat stroke in hot weather.
  • Report sore throat, fever, unusual bleeding or bruising, rash, weakness, tremors, impaired vision, dark urine, pale stools, yellowing of the skin or eyes.