Overview
This lecture covers the pharmacology, indications, contraindications, dosing, administration, and safety details of loratadine, a non-sedating antihistamine.
Mechanism of Action
- Loratadine is a non-sedating antihistamine that blocks peripheral H1 histamine receptors.
- By inhibiting histamine, it reduces itching and redness during allergic reactions.
- Antihistamines counteract histamine, a mediator released during inflammation.
Indications
- Used for minor allergic reactions limited to skin symptoms.
- Used for itch or rash with anaphylaxis, only if systemic symptoms are improving.
Contraindications and Cautions
- Contraindicated in those with known severe allergy to loratadine or age less than one year.
- Use with caution during pregnancy; usually withheld unless essential.
- Safe to administer when breastfeeding, but advise stopping breastfeeding and seeking medical guidance.
Dosage & Administration
- Adults and children ≥12 years: 20 mg orally.
- Children 1–11 years: 10 mg orally.
- Give orally; crush tablets in soft food for those who can't swallow.
- Follow the five 'rights': right patient, medicine, dose, route, and time.
Adverse Effects and Onset
- No common adverse effects reported.
- Onset of action: 30 –60 minutes.
- Duration of effect: 12–24 hours.
Pharmacokinetics
- Predominantly metabolised by the liver.
- No significant effect from liver impairment in acute use.
Drug Interactions
- No common drug interactions.
- Plasma loratadine may increase with ketoconazole, erythromycin, or roxithromycin, with possible QT prolongation on ECG after long-term use.
Additional Information
- Loratadine is typically packaged as 10 mg tablets.
- Any healthcare personnel may provide loratadine for self-administration if package instructions are followed.
Key Terms & Definitions
- Antihistamine — A medication that blocks the effects of histamine.
- Histamine — A chemical mediator causing inflammation and itching.
- Inotrope — A substance that increases heart muscle contractility.
- PO (per-oral) — Administration by mouth.
Action Items / Next Steps
- Complete the accompanying quiz on loratadine.
- Review the skill sheet: Loratadine (Clinical Wiki).