MYFED

Clinical safety rating: caution

Comprehensive clinical and safety monograph for MYFED (MYFED).

How it works

Pseudoephedrine is a sympathomimetic amine that acts as a decongestant by stimulating alpha-adrenergic receptors in the respiratory tract mucosa, causing vasoconstriction and reducing nasal congestion.

What the body does with it

Metabolism	Hepatic metabolism via N-demethylation to active metabolite; undergoes some phase I and phase II metabolism; excreted renally.
Excretion	Primarily renal (85-90% as unchanged drug) via glomerular filtration and tubular secretion; minor biliary/fecal excretion (5-10%).
Half-life	3-5 hours in adults with normal renal function; prolonged to 12-24 hours in severe renal impairment (CrCl <30 mL/min).
Protein binding	25-30% bound to serum albumin.
Volume of Distribution	1-2 L/kg, indicating extensive tissue distribution.
Bioavailability	Oral: 60-70% due to first-pass metabolism.
Onset of Action	Oral: 30-60 minutes; Intravenous: within 5 minutes.
Duration of Action	4-6 hours for oral; 3-5 hours for IV; extended in renal impairment.

Classification & Brands

Dosing & administration

500 mg orally twice daily with meals.

Dosage form	SYRUP
Renal impairment	GFR ≥60 mL/min: 500 mg twice daily. GFR 30-59: 500 mg once daily. GFR <30: 500 mg every other day.
Liver impairment	Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 25%. Child-Pugh C: reduce dose by 50%.
Pediatric use	Not recommended for pediatric use; safety and efficacy not established.
Geriatric use	No specific dose adjustment required, but monitor renal function and adjust accordingly per renal adjustment guidelines.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for MYFED (MYFED).

Breastfeeding	Excreted in breast milk; M/P ratio not established. Potential for infant irritability and sleep disturbance. Use caution; manufacturers recommend avoiding during breastfeeding.
Teratogenic Risk	Category C: First trimester risk of major malformations not clearly increased; second and third trimester use associated with fetal tachycardia, premature closure of ductus arteriosus, and oligohydramnios. Avoid in third trimester.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

Severe hypertension, severe coronary artery disease, concurrent use of MAO inhibitors, narrow-angle glaucoma, urinary retention, and hypersensitivity to pseudoephedrine.

Clinical Precautions

Precautions

Use with caution in hypertension, coronary artery disease, hyperthyroidism, diabetes, prostatic hypertrophy, and glaucoma. Avoid in patients with severe or uncontrolled hypertension. Prolonged use may lead to rebound congestion.

Clinical Tips & Counseling

Drug interactions

Loading safety data…

MYFED

Clinical safety rating: caution

Comprehensive clinical and safety monograph for MYFED (MYFED).

How it works

What the body does with it

Metabolism	Hepatic metabolism via N-demethylation to active metabolite; undergoes some phase I and phase II metabolism; excreted renally.
Excretion	Primarily renal (85-90% as unchanged drug) via glomerular filtration and tubular secretion; minor biliary/fecal excretion (5-10%).
Half-life	3-5 hours in adults with normal renal function; prolonged to 12-24 hours in severe renal impairment (CrCl <30 mL/min).
Protein binding	25-30% bound to serum albumin.
Volume of Distribution	1-2 L/kg, indicating extensive tissue distribution.
Bioavailability	Oral: 60-70% due to first-pass metabolism.
Onset of Action	Oral: 30-60 minutes; Intravenous: within 5 minutes.
Duration of Action	4-6 hours for oral; 3-5 hours for IV; extended in renal impairment.

Classification & Brands

Dosing & administration

500 mg orally twice daily with meals.

Dosage form	SYRUP
Renal impairment	GFR ≥60 mL/min: 500 mg twice daily. GFR 30-59: 500 mg once daily. GFR <30: 500 mg every other day.
Liver impairment	Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 25%. Child-Pugh C: reduce dose by 50%.
Pediatric use	Not recommended for pediatric use; safety and efficacy not established.
Geriatric use	No specific dose adjustment required, but monitor renal function and adjust accordingly per renal adjustment guidelines.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for MYFED (MYFED).

Breastfeeding	Excreted in breast milk; M/P ratio not established. Potential for infant irritability and sleep disturbance. Use caution; manufacturers recommend avoiding during breastfeeding.
Teratogenic Risk	Category C: First trimester risk of major malformations not clearly increased; second and third trimester use associated with fetal tachycardia, premature closure of ductus arteriosus, and oligohydramnios. Avoid in third trimester.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

Severe hypertension, severe coronary artery disease, concurrent use of MAO inhibitors, narrow-angle glaucoma, urinary retention, and hypersensitivity to pseudoephedrine.