Promethazine hydrochloride
Promethazine hydrochloride (Phenergan)
Promethazine hydrochloride
(proh- METH-ah-zeen)
Pregnancy Category: C Parenteral: Anergan 50 Phenergan Suppositories: Phenergan Syrup: Phenergan Fortis Phenergan Plain Tablets: Phenergan PMS Promethazine (Rx)

Classification: Antihistamine, phenothiazine-type

See Also: See also Antihistamines and Antiemetics .

Action/Kinetics: Antiemetic effects are likely due to inhibition of the CTZ. Effective in vertigo by its central anticholinergic effect which inhibits the vestibular apparatus and the integrative vomiting center as well as the CTZ. May cause severe drowsiness. Onset, PO, IM, PR: 20 min; IV: 3-5 min. Duration, antihistaminic: 6-12 hr; sedative: 2-8 hr. Slowly eliminated through urine and feces.

Uses: PO and PR for prophylaxis and treatment of motion sickness. Prophylaxis of N&V; due to anesthesia or surgery (also postoperatively). Pre- or postoperative sedative, obstetric sedative. Hypersensitivity reactions, including perennial and seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, urticaria, angioedema, allergic reactions to blood or plasma, dermographism. Adjunct in the treatment of anaphylaxis or anaphylactoid reactions. Adjunct to analgesics for postoperative pain. IV with meperidine or other narcotics in special surgical procedures as bronchoscopy, ophthalmic surgery, or in poor-risk clients.

Contraindications: Lactation. Comatose clients, CNS depression due to drugs, previous phenothiazine idiosyncrasy, acutely ill or dehydrated children (due to greater susceptibility to dystonias). Children up to 2 years of age. SC or intra-arterial use due to tissue necrosis and gangrene.

Special Concerns: Safe use during pregnancy has not been established. Use in children may cause paradoxical hyperexcitability and nightmares. Geriatric clients are more likely to experience confusion, dizziness, hypotension, and sedation.

Additional Side Effects: Leukopenia and agranulocytosis (especially if used with cytotoxic agents).

How Supplied: Injection: 25 mg/mL, 50 mg/mL; Suppository: 12.5 mg, 25 mg, 50 mg; Syrup: 6.25 mg/5 mL, 25 mg/5 mL; Tablet: 12.5 mg, 25 mg, 50 mg

Dosage
?Suppositories, Syrup, Tablets Hypersensitivity reactions.
Adults: 12.5 mg q.i.d. before meals and at bedtime (or 25 mg at bedtime if needed). Pediatric over 2 years: 0.125 mg/kg (3.75 mg/m ²) q 4-6 hr; 0.5 mg/kg (15 mg/m ²) at bedtime if needed; or, 6.25-12. mg t.i.d. (or 25 mg at bedtime if needed).
Antiemetic.
Adults: 25 mg (usual); 12.5-25 mg q 4-6 hr as needed. Pediatric, over 2 years: 0.25-0.5 mg/kg (7.5-15 mg/m ²) q 4-6 hr as needed (or 12.5-25 mg q 4-6 hr).
Sedation.
Adults: 25-50 mg at bedtime; pediatric, over 2 years: 0.5-1 mg/kg (15-30 mg/m ²) or 12.5-25 mg at bedtime.
Motion sickness.
Adults: 25 mg b.i.d. Pediatric, over 2 years: 12.5-25 mg b.i.d.
Analgesia adjunct.
Adults: 50 mg with an equal amount of meperidine and an appropriate dose of an atropine-like agent. Pediatric, over 2 years: 1.2 mg/kg with an equal amount of meperidine and an atropine-like agent.
?IM, IV Hypersensitivity reactions.
Adults: 25 mg repeated in 2 hr if needed; pediatric, 2-12 years: 12.5 mg or less, not to exceed half the adult dose. Resume PO therapy as soon as possible.
Antiemetic.
Adults: 12.5-25 mg q 4 hr if needed. If used postoperatively, reduce doses of concomitant hypnotics, analgesics, or barbiturates. Pediatric, 2-12 years: Do not exceed half the adult dose. Do not use when the cause of vomiting is unknown.
Sedation.
Adults: 25-50 mg at bedtime. May be combined with hypnotics for pre- and postoperative sedation. Pediatric, 2-12 years: Do not exceed half the adult dose.
Sedation during labor.
Adults: 50 mg during early stages of labor, not to exceed 100 mg/24 hr.
Analgesia adjunct.
Adults: 25-50 mg in combination with reduced doses of analgesics and hypnotics; give atropine-like drugs as needed. Pediatric, 2-12 years: 1.2 mg/kg in combination with an equal dose of analgesic or barabiturate and an appropriate dose of an atropine-like drug.