Dosing and uses of Dexchlorpheniramine
Adult dosage forms and strengths
syrup
- 2mg/5mL
Allergy Symptoms
2 mg PO q4-6hr
Pediatric dosage forms and strengths
syrup
- 2mg/5mL
Allergy Symptoms
2-6 years: Syrup: 0.5 mg PO q4-6hr
6-11 years: (syrup) 1 mg PO q4-6hr
>12 years: As adults; (syrup) 2 mg PO q4-6hr
Geriatric dosage forms and strengths
Dose at lower end of dosage range (2 mg PO q4-6hr) or administer less frequently
Nonanticholinergic antihistamines should be considered first when treating allergic reactions (Beers Criteria)
Avoid use in elderly because of high incidence of anticholinergic effects
Clearance reduced with advanced age, greater risk of confusion, dry mouth, constipation, and other anticholinergic effects and toxicity
May exacerbate existing lower urinary conditions or benign prostatic hyperplasia
Pregnancy and lactation
Pregnancy category: B
Lactation: excretion in milk unknown/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 Dexchlorpheniramine
Mechanism of action
Histamine H1-receptor antagonist in blood vessels, respiratory tract, and gastrointestinal tract
Pharmacokinetics
Half-Life: 20-30 hr
Onset: 6 hr
Duration: 24 hr
Peak Plasma Time: 3 hr
Protein Bound: 69-72%
Excretion: Urine
Vd: 2.5-3.2 L/kg (adults); 3.8 L/kg (Children)
Metabolism: Hepatic
Metabolites: Unidentified, at least 2
Sedative effects: Low
Antihistamine activity: High
Anticholinergic activity: Moderate