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promethazine hydrochloride
Anergan 25, Anergan 50, Histantil†, Pentazine, Phencen-50, Phenergan*, Phenergan Fortis*, Phenergan Plain*, Phenoject-50, PMS-Promethazine†, Pro-50, Promethegan, Prorex-25, Prorex-50, Prothazine*, Prothazine Plain, V-Gan-25, V-Gan-50

promethazine theoclate
Avomine‡

Pregnancy Risk Category C

How supplied
promethazine hydrochloride

Tablets:
12.5 mg, 25 mg, 50 mg
Syrup:
5 mg/5 ml‡*, 6.25 mg/5 ml*, 10 mg/5 ml†*, 25 mg/5 ml*
Injection:
25 mg/ml, 50 mg/ml
Suppositories:
12.5 mg, 25 mg, 50 mg
promethazine theoclate

Tablets:
25 mg‡

Action
Phenothiazine derivative that competes with histamine for H1-receptor sites on effector cells. Prevents, but doesn't reverse, histamine-mediated responses. At high doses, also exhibits local anesthetic effects.

Indications & dosage
Motion sickness--

Adults:
25 mg P.O. b.i.d.
Children:
12.5 to 25 mg P.O. or P.R. b.i.d. Or 0.5 mg/kg 30 minutes to 1 hour before departure.
Nausea--

Adults:
12.5 to 25 mg P.O., I.M., or P.R. q 4 to 6 hours, p.r.n.
Children:
12.5 to 25 mg P.O. or P.R. q 4 to 6 hours, p.r.n. Or 0.25 to 1 mg/kg q 4 to 6 hours, p.r.n. Or 6.25 to 12.5 mg I.M. q 4 to 6 hours, p.r.n.
Rhinitis, allergy symptoms--

Adults:
12.5 mg P.O. q.i.d.; or 25 mg P.O. h.s.
Children:
6.25 to 12.5 mg P.O. t.i.d. or 25 mg P.O. or P.R. h.s. Or, 0.1 mg/kg q 6 hours during the day and 0.5 mg/kg h.s.
Sedation--

Adults:
25 to 50 mg P.O. or I.M. h.s. or p.r.n.
Children:
12.5 to 25 mg P.O., I.M., or P.R. h.s. Or 0.5 to 1 mg/kg q 6 hours, p.r.n.
Routine preoperative or postoperative sedation, adjunct to analgesics--

Adults:
25 to 50 mg I.M., I.V., or P.O.
Children:
12.5 to 25 mg I.M., I.V., or P.O.

Adverse reactions
CNS:
sedation, confusion, sleepiness, dizziness, disorientation, extrapyramidal symptoms, drowsiness.
CV:
hypotension, hypertension.
EENT:
blurred vision.
GI:
nausea, vomiting, dry mouth.
GU:
urine retention.
Hematologic:
leukopenia, agranulocytosis, thrombocytopenia.
Metabolic:
hyperglycemia.
Skin:
photosensitivity, rash.

Interactions
Drug-drug.
Anticholinergics, phenothiazines, tricyclic antidepressants: increased effects. Don't give together.
CNS depressants:
increased sedation. Use together cautiously.
Epinephrine:
may block or reverse the effects of epinephrine. Use other pressor drugs instead.
Levodopa:
may decrease levodopa's antiparkinsonian action. Avoid concomitant use.
Lithium:
may reduce GI absorption or enhance renal elimination of lithium. Avoid concomitant use.
MAO inhibitors:
increased extrapyramidal effects. Don't use together.
Drug-lifestyle.
Alcohol use: increased sedation. Use together cautiously.
Sun exposure:
photosensitivity reactions may occur. Avoid prolonged and unprotected sun exposure.

Effects on diagnostic tests
Discontinue drug 4 days before performing diagnostic skin tests. Antihistamines can prevent, reduce, or mask positive skin test response. Drug may cause either false-positive or false-negative pregnancy test results. It may also interfere with blood grouping in the ABO system.

Contraindications
Contraindicated in patients with hypersensitivity to drug and in those with intestinal obstruction, prostatic hyperplasia, bladder-neck obstruction, angle-closure glaucoma, seizure disorders, coma, CNS depression, stenosing or peptic ulcerations; also contraindicated in newborns, premature neonates, breast-feeding women; and acutely ill or dehydrated children.

Nursing considerations

I.V. administration

Patient teaching

*Liquid contains alcohol. **May contain tartrazine.  †Canada  ‡Australia  §U.K.  OTCOver the counter
Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE-THREATENING

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