Dosing and uses of Promethazine DM (promethazine/dextromethorphan)
Adult dosage forms and strengths
promethazine/dextromethorphan
oral syrup
- (6.25mg/15mg)/5mL
Cough
Temporary relief of cough and upper respiratory tract symptoms associated with allergy or the common cold
6.25 mg/15 mg (5 mL) PO q4-6hr PRn
Maximum: 30 mL/24 hr
Other Information
Administer with special measuring device for accurate dose
Pediatric dosage forms and strengths
promethazine/dextromethorphan
oral syrup
- (6.25mg/15mg)/5mL
Cough
<2 years: Contraindicated
2 to <6 years: 1.25-2.5 mL PO q4-6hr, up to 12.5 mg/30 mg (10 mL) in 24 hr
6 to <12 years: 2.5-5 mL PO 4-6hr, up to 25 mg/60 mg (20 mL) in 24 hr
12 years and older: As in adults; 6.25 mg/15 mg (5 mL) PO q4-6hr PRN, not to exceed 30 mL/24 hr
Promethazine DM (promethazine/dextromethorphan) adverse (side) effects
Frequency not defined
Promethazine
- Anticholinergic effects: dry mouth, blurred vision
- Tachy/bradycardia
- Confusion, disorientation, EPS, sedation
- Photosensitivity
- Agranulocytosis, leukopenia
- Obstructive jaundice
Dextromethorphan
- Dizziness
- Drowsiness
- Sedation
- Constipation
- Nausea
- Vomiting
- Blurred vision
- Nystagmus
Warnings
Black box warnings
Do not use in patients younger than 2 years of age because of potential for fatal respiratory depression; Administer with caution to children older than 2 years of age
Contraindications
Promethazine
- Hypersensitivity
- Newborn/premature infants, <2 yo (risk of potentially fatal respiratory depression)
- Subcutaneous or intra-arterially administration
- BPH
- Narrow angle glaucoma
- Pyloroduodenal obstruction, stenosing peptic ulcer, bladder neck obstruction
- Severe CNS depression
- Coma, Severe respiratory depression
Dextromethorphan
- Concurrent nonselective MAO inhibitors: serotonin syndrome
Cautions
Promethazine
- CVD, asthma, hepatic impairment, peptic ulcer, respiratory impairment
- Anaphylaxis in susceptible individuals
- May impair ability to drive or perform hazardous tasks
- Monitor closely in patients with
- - Cardiovascular disease
- - Hepatic impairment
- - Reye syndrome
- - History of sleep apnea
- Depresses hypothalamic thermoregulatory mechanism; exposure to extreme temperatures may cause hypo- or hyperthermia
- Antiemetic effect may obscure toxicity of chemotherapeutic drugs
Dextromethorphan
- Phenylketonuria: contains aspartame
Pregnancy and lactation
Pregnancy category: C
Lactation: Not recommended
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Promethazine DM (promethazine/dextromethorphan)
Promethazine
Onset: 20 min
Duration: 4-6 hr
Bioavailability: low
Protein Bound: 93%
Vd: 12.9-17.7 L/hr
Metabolism: hepatic P450 enzyme CYP2D6
Metabolites: promethazine sulfoxide and glucuronides (inactive)
Excretion: urine, feces
Dialyzable: no
Dextromethorphan
Onset: 15-30 min
Duration: 3-6 hr
Metabolism: hepatic P450 enzyme CYP2D6
Excretion: urine
Mechanism of action
Promethazine: Antidopaminergic effect due to blocking mesolimbic dopamine receptors and alpha-adrenergic receptors in the brain; antihistaminic effect due to blocking H1-receptors
Dextromethorphan: Acts on cough center in medulla; derivative of levorphanoL
