Second-generation H1 antihistamine (active loratadine metabolite)
Desloratadine is a non-sedating antihistamine, used to relieve the symptoms of allergic rhinitis (sneezing, runny nose, itchy eyes and nose). It is taken once a day and causes little drowsiness. It is the active metabolite of loratadine.
Also known as: Aerius, desloratadina, desloratadine
Desloratadine + ketoconazole: possible increased desloratadine concentrations.
Ketoconazole, by inhibiting CYP3A4, can raise desloratadine concentrations; however, desloratadine and its active metabolite have a wide safety margin and the combination is not associated with significant QT prolongation (unlike the old terfenadine/astemizole). In practice, the interaction is generally well tolerated; monitor drowsiness or sedation in susceptible patients and use the lowest effective antihistamine dose during antifungal treatment.
Ketoconazole + desloratadine: the azole raises desloratadine levels (CYP3A4), usually without relevant QT prolongation. Monitor drowsiness.
Ketoconazole inhibits CYP3A4, raising desloratadine levels.
Symptoms of antihistamine excess.
Drowsiness, palpitations, dizziness.
Watch for sedation and adverse effects.
DailyMed (FDA) — approved Desloratadine label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2a90b899-7746-43dc-ac8a-e754428eb30c ; approved Ketoconazole label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f162e616-21b4-49b1-b437-15e21001a6f0 — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Desloratadine + erythromycin: possible increased desloratadine concentrations.
The desloratadine label documents that coadministration with "erythromycin... resulted in increased plasma concentrations of desloratadine and 3-hydroxydesloratadine, but there were no clinically relevant changes in the safety profile of desloratadine" — desloratadine is metabolised by CYP3A4 (and CYP2D6), which erythromycin inhibits. The combination is generally well tolerated; the main concerns are potentiation of somnolence/CNS effects (especially in the elderly) and the QT risk of erythromycin itself, which "should be avoided in patients with known QT prolongation, uncorrected hypokalaemia or hypomagnesaemia, clinically significant bradycardia, and with class IA/III antiarrhythmics" (erythromycin label). Routine dose adjustment of desloratadine is not needed; watch for somnolence and inform the patient.
Erythromycin + desloratadine: erythromycin (CYP3A4 inhibitor) raises desloratadine levels, without clinically relevant safety changes. Watch for somnolence.
Erythromycin reduces desloratadine metabolism (CYP3A4).
Antihistamine adverse effects.
Drowsiness, dry mouth, headache.
Watch for sedation; dose adjustment is usually not required.
DailyMed (FDA) — approved Desloratadine label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2a90b899-7746-43dc-ac8a-e754428eb30c ; approved Erythromycin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0c05e1f7-a3d4-8e69-e063-6394a90aecc3 — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Grapefruit (juice) may raise desloratadine concentrations.
Avoid grapefruit juice during treatment.
EMC-UK (MHRA) — approved Desloratadine SmPC: https://www.medicines.org.uk/emc/product/14722/smpc
Alcohol may potentiate drowsiness.
Limit alcohol in susceptible patients.
EMC-UK (MHRA) — approved Desloratadine SmPC: https://www.medicines.org.uk/emc/product/14722/smpc
Reduced elimination may increase exposure.
Use with caution.
EMC-UK (MHRA) — approved Desloratadine SmPC: https://www.medicines.org.uk/emc/product/14722/smpc
Desloratadine is eliminated renally.
Use with caution and adjust the dose in severe renal impairment.
EMC-UK (MHRA) — approved Desloratadine SmPC: https://www.medicines.org.uk/emc/product/14722/smpc
Limited data in pregnancy; active loratadine metabolite.
Use only if benefit justifies risk; prefer loratadine/cetirizine when available.
Limited data; prefer to avoid during breastfeeding.
No specific additional contraception.
EMC-UK (MHRA) — approved Desloratadine SmPC: https://www.medicines.org.uk/emc/product/14722/smpc
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Long-acting tricyclic H1 antihistamine, non-sedating (does not readily cross the blood-brain barrier), indicated for allergic rhinitis and urticaria. Antihistaminic effect (wheal and flare) within 1 hour, persisting up to 24 hours, without tachyphylaxis over 28 days. No clinically relevant QTc prolongation (mean increase of 8.1 ms by Bazett method at 45 mg/day, with no adverse events).
Long-acting selective histamine H1-receptor antagonist (significant interaction with the human H1 receptor at 2-3 ng/mL); inhibits histamine release from human mast cells in vitro. Does not readily cross the blood-brain barrier (radiolabelled tissue distribution and H1-receptor binding studies).
Tmax of about 3 hours after a 5 mg oral dose (mean steady-state Cmax ~4 ng/mL, AUC 56.9 ng·h/mL). Neither food nor grapefruit juice affects bioavailability. Plasma protein binding of 82-87% (desloratadine) and 85-89% (3-hydroxydesloratadine). Cmax and AUC dose-proportional between 5-20 mg.
Extensively metabolised to 3-hydroxydesloratadine (an active metabolite), which is subsequently glucuronidated; the responsible enzymes have not been identified. About 6% of the population are poor metabolisers (half-life >50 h or 3-OH/desloratadine AUC ratio <0.1; more frequent in Blacks, 17%). Mass balance study: recovery of ~87% of the dose, equally distributed in urine and faeces as metabolic products.
Mean plasma elimination half-life of approximately 27 hours (33.7 h in elderly subjects ≥65 years); 3-hydroxydesloratadine shows similar Tmax and half-life. In hepatic impairment AUC increases ~2.4-fold and half-life is prolonged; in severe renal impairment AUC increases ~2.5-fold. Allows once-daily dosing.
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
