CLARITIN-D 24 HOUR

Clinical safety rating: caution

Comprehensive clinical and safety monograph for CLARITIN-D 24 HOUR (CLARITIN-D 24 HOUR).

How it works

Loratadine is a long-acting tricyclic antihistamine with selective peripheral H1-receptor antagonism; pseudoephedrine is a sympathomimetic amine that acts as an alpha-adrenergic agonist, causing vasoconstriction in the nasal mucosa.

What the body does with it

Metabolism	Loratadine: extensively metabolized by CYP3A4 and CYP2D6 to active metabolite desloratadine; pseudoephedrine: partially metabolized in liver by N-demethylation.
Excretion	Renal (40%) as unchanged drug and metabolites; biliary/fecal (minor). Approximately 27% of loratadine and 40% of desloratadine are excreted in urine over 10 days.
Half-life	Loratadine: 8-11 hours (mean 10.6 ± 4.6 h); desloratadine: 17-24 hours (mean 19.4 ± 7.5 h). Terminal half-life is prolonged in chronic hepatic impairment (mean 37 h for loratadine, 47 h for desloratadine).
Protein binding	Loratadine: 97-99% bound to plasma proteins (mainly albumin and α1-acid glycoprotein); desloratadine: 73-76% bound.
Volume of Distribution	Loratadine: 119 L/kg (apparent Vd/F ~1000 L). High Vd indicates extensive tissue distribution. Desloratadine: 148 L/kg (apparent Vd/F ~2500 L).
Bioavailability	Oral: Loratadine absolute bioavailability is ~40% due to first-pass metabolism; food increases AUC by 40% and delays Tmax. Desloratadine absolute bioavailability is ~50%.
Onset of Action	Oral: Symptom relief begins within 1-3 hours; maximum effect at 2-4 hours.
Duration of Action	24 hours (clinical effect persists for 24 hours). Steady-state achieved after 5 days of once-daily dosing.

Classification & Brands

Dosing & administration

1 tablet (10 mg loratadine/240 mg pseudoephedrine) orally once daily

Dosage form	TABLET, EXTENDED RELEASE
Renal impairment	GFR 30-89 mL/min: no adjustment; GFR <30 mL/min or ESRD: contraindicated due to pseudoephedrine component
Liver impairment	Child-Pugh class A: no adjustment; Child-Pugh class B or C: contraindicated due to insufficient data
Pediatric use	Not recommended for children under 12 years; age 12-17 years: 1 tablet orally once daily
Geriatric use	Caution in patients >60 years due to increased sensitivity to pseudoephedrine (nervousness, dizziness, sleep disturbances) and higher risk of adverse effects; consider alternative therapy

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for CLARITIN-D 24 HOUR (CLARITIN-D 24 HOUR).

Breastfeeding	Loratadine: M/P ratio ~1.2; excreted in breast milk in low amounts (0.029% of maternal dose). Pseudoephedrine: M/P ratio ~3.5; excreted in milk (4-6% of maternal dose), may reduce milk production and cause irritability in infants. Use caution, especially with high doses or prolonged use.
Teratogenic Risk	FDA Pregnancy Category B. Animal studies show no fetal risk; no adequate human studies in first trimester. Pseudoephedrine may cause uterine vasoconstriction; avoid in preeclampsia or reduced placental perfusion. No known teratogenicity from loratadine or pseudoephedrine in human pregnancy.

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to loratadine, pseudoephedrine, or any component","Severe hypertension","Severe coronary artery disease","Concurrent use or within 14 days of MAOIs","Narrow-angle glaucoma","Urinary retention","Lactation (due to pseudoephedrine)"]

Clinical Precautions

Precautions	["Cardiovascular effects: caution in hypertension, arrhythmias, ischemic heart disease","Central nervous system stimulation: may cause insomnia, dizziness, tremor","Urinary retention: caution in patients with prostatic hypertrophy","Glaucoma: may increase intraocular pressure","Use with MAOIs: hypertensive crisis risk","Diabetes: may increase blood glucose"]
Food/Dietary	Avoid high-tyramine foods (e.g., aged cheeses, cured meats, fermented products) due to potential hypertensive crisis with pseudoephedrine. Grapefruit juice may increase pseudoephedrine absorption; limit intake. Avoid alcohol, which can exacerbate CNS sedation from loratadine.

Clinical Tips & Counseling

Drug interactions

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CLARITIN-D 24 HOUR

Clinical safety rating: caution

Comprehensive clinical and safety monograph for CLARITIN-D 24 HOUR (CLARITIN-D 24 HOUR).

How it works

What the body does with it

Metabolism	Loratadine: extensively metabolized by CYP3A4 and CYP2D6 to active metabolite desloratadine; pseudoephedrine: partially metabolized in liver by N-demethylation.
Excretion	Renal (40%) as unchanged drug and metabolites; biliary/fecal (minor). Approximately 27% of loratadine and 40% of desloratadine are excreted in urine over 10 days.
Half-life	Loratadine: 8-11 hours (mean 10.6 ± 4.6 h); desloratadine: 17-24 hours (mean 19.4 ± 7.5 h). Terminal half-life is prolonged in chronic hepatic impairment (mean 37 h for loratadine, 47 h for desloratadine).
Protein binding	Loratadine: 97-99% bound to plasma proteins (mainly albumin and α1-acid glycoprotein); desloratadine: 73-76% bound.
Volume of Distribution	Loratadine: 119 L/kg (apparent Vd/F ~1000 L). High Vd indicates extensive tissue distribution. Desloratadine: 148 L/kg (apparent Vd/F ~2500 L).
Bioavailability	Oral: Loratadine absolute bioavailability is ~40% due to first-pass metabolism; food increases AUC by 40% and delays Tmax. Desloratadine absolute bioavailability is ~50%.
Onset of Action	Oral: Symptom relief begins within 1-3 hours; maximum effect at 2-4 hours.
Duration of Action	24 hours (clinical effect persists for 24 hours). Steady-state achieved after 5 days of once-daily dosing.

Classification & Brands

Dosing & administration

1 tablet (10 mg loratadine/240 mg pseudoephedrine) orally once daily

Dosage form	TABLET, EXTENDED RELEASE
Renal impairment	GFR 30-89 mL/min: no adjustment; GFR <30 mL/min or ESRD: contraindicated due to pseudoephedrine component
Liver impairment	Child-Pugh class A: no adjustment; Child-Pugh class B or C: contraindicated due to insufficient data
Pediatric use	Not recommended for children under 12 years; age 12-17 years: 1 tablet orally once daily
Geriatric use	Caution in patients >60 years due to increased sensitivity to pseudoephedrine (nervousness, dizziness, sleep disturbances) and higher risk of adverse effects; consider alternative therapy

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for CLARITIN-D 24 HOUR (CLARITIN-D 24 HOUR).

Breastfeeding	Loratadine: M/P ratio ~1.2; excreted in breast milk in low amounts (0.029% of maternal dose). Pseudoephedrine: M/P ratio ~3.5; excreted in milk (4-6% of maternal dose), may reduce milk production and cause irritability in infants. Use caution, especially with high doses or prolonged use.
Teratogenic Risk	FDA Pregnancy Category B. Animal studies show no fetal risk; no adequate human studies in first trimester. Pseudoephedrine may cause uterine vasoconstriction; avoid in preeclampsia or reduced placental perfusion. No known teratogenicity from loratadine or pseudoephedrine in human pregnancy.

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

Clinical Precautions

Precautions	["Cardiovascular effects: caution in hypertension, arrhythmias, ischemic heart disease","Central nervous system stimulation: may cause insomnia, dizziness, tremor","Urinary retention: caution in patients with prostatic hypertrophy","Glaucoma: may increase intraocular pressure","Use with MAOIs: hypertensive crisis risk","Diabetes: may increase blood glucose"]
Food/Dietary	Avoid high-tyramine foods (e.g., aged cheeses, cured meats, fermented products) due to potential hypertensive crisis with pseudoephedrine. Grapefruit juice may increase pseudoephedrine absorption; limit intake. Avoid alcohol, which can exacerbate CNS sedation from loratadine.

Clinical Tips & Counseling

Drug interactions

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Clinical Pearls	CLARITIN-D 24 HOUR combines loratadine (antihistamine) and pseudoephedrine (decongestant). Avoid in patients with severe hypertension, coronary artery disease, or MAOI use within 14 days. Monitor for insomnia, tachycardia, and urinary retention, especially in elderly males with BPH. Contraindicated in narrow-angle glaucoma.
Patient Advice	Do not crush or chew the tablet; swallow whole with a full glass of water. · Avoid taking within 4-6 hours of bedtime to prevent insomnia. · Do not use with other decongestants or cold remedies containing pseudoephedrine. · Discontinue and consult healthcare provider if you experience chest pain, rapid heart rate, dizziness, or difficulty urinating.