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Action/Kinetics:
Thought to stimulate both alpha and beta receptors as well as to act indirectly through release of norepinephrine from storage sites. Increases in BP are due mainly to increased CO rather than to vasoconstriction; has minimal CNS effects. Acts on alpha-adrenergic receptors to produce a decongestant effect in the nasal mucosa.
Onset, decongestant: 15-30 min;
peak plasma levels: 1-2 hr;
duration, capsules and tablets: 3 hr;
extended-release tablets: 12-16 hr.
Peak plasma levels: 100 ng.
t
1/2: 3-4 hr. Eighty percent to 90% excreted in the urine unchanged.
Uses:
Nasal congestion due to colds, hay fever, allergies. Short-term (8-12 weeks) treatment of exogenous obesity in conjunction with a weight reduction program including reduced caloric intake, exercise, and behavior modification.
Investigational: Mild to moderate stress incontinence in women.
Contraindications:
Arteriosclerosis, depression, glaucoma, hypertension, diabetes, kidney disease, hyperthyroidism, during or within 14 days of use of MAO inhibitors, hypersensitivity to sympathomimetics. Use as an anorexiant for children less than 12 years of age. Sustained-release forms during lactation and in children less than 12 years of age.
Special Concerns:
Safety and efficacy during pregnancy and lactation and for children not established. Children less than 6 years of age may be at greater risk for developing psychiatric disorders when using phenylpropanolamine. Individualize the anorexiant dose for children 12-18 years of age.
Side Effects:
CNS: Dizziness, headache, insomnia, restlessness, bizarre behavior. Serious effects due to abuse include: agitation, tremor, increased motor activity, hallucinations,
seizures, stroke, and death.
CV: Palpitations,
hypertension (may be severe and lead to crisis) tachycardia.
Miscellaneous: Dry mouth, dysuria, renal failure, nausea, nasal dryness.
Additional Drug Interactions:
-
Bromocriptine / Worsening of side effects of bromocriptine; possibility of VT and cardiac dysfunction
-
Caffeine /
Serum caffeine levels
risk pharmacologic/toxic effects
-
Indomethacin / Possibility of severe hypertensive episode
How Supplied:
Capsule: 37.5 mg;
Capsule, Extended Release: 75 mg;
Tablet: 25 mg, 37.5 mg, 50 mg;
Tablet, Extended Release: 75 mg
Dosage
?Capsules, Tablets
Decongestant.
Adults: 25 mg q 4 hr or 50 mg q 6-8 hr (not to exceed 150 mg/day);
Children, 2-6 years: 6.25 mg q 4 hr, not to exceed 37.5 mg in 24 hr;
6-12 years: 12.5 mg q 4 hr, not to exceed 75 mg in 24 hr.
Anorexiant.
Adults: 25 mg t.i.d. 30 min before meals, not to exceed 75 mg in 24 hr.
?Extended-Release Capsules, Extended-Release Tablets
Decongestant.
Adults: 75 mg q 12 hr.
Anorexiant.
Adults: 75 mg once daily in the morning.
