Loratadine Dosing
For adults and children ≥6 years, administer loratadine 10 mg once daily; for children 2 to <6 years, give 5 mg once daily. 1
Standard Dosing by Age Group
Adults and Children ≥6 Years
- 10 mg once daily (2 teaspoonfuls of syrup or one 10 mg tablet) 1
- Do not exceed 10 mg in 24 hours 1
- Onset of action occurs within 1 hour, with duration of at least 24 hours 2
Children 2 to <6 Years
- 5 mg once daily (1 teaspoonful of syrup) 1
- Do not exceed 5 mg in 24 hours 1
- This dose provides similar systemic exposure to the adult 10 mg dose when adjusted for body weight 3
Children <2 Years
- Consult a physician before use 1
- Safety and efficacy have not been adequately established in this age group 1
Dosing in Renal or Hepatic Impairment
Patients with liver or kidney disease should consult a physician before using loratadine. 1
- The FDA label recommends caution in renal or hepatic impairment but does not provide specific dose adjustments 1
- Loratadine is metabolized hepatically to its active metabolite descarboethoxyloratadine, which has four times the activity of the parent drug 2
- In severe renal impairment (creatinine clearance <10 mL/min), loratadine and desloratadine should be used with caution, though the British guidelines suggest halving the dose of related antihistamines like cetirizine in this setting 4
Clinical Pharmacology Considerations
Pharmacokinetics
- Peak plasma concentration of loratadine occurs at 1-2 hours; the active metabolite peaks at 2-4 hours 3, 2
- Elimination half-life is approximately 10 hours for loratadine and 20 hours for descarboethoxyloratadine 2
- In children aged 2-5 years receiving 5 mg, peak concentrations were 7.78 ng/mL for loratadine and 5.09 ng/mL for desloratadine 3
Efficacy
- Loratadine is superior to placebo and as effective as other second-generation antihistamines (cetirizine, terfenadine) for allergic rhinitis and chronic urticaria 5
- In children aged 3-12 years with allergic rhinitis, loratadine syrup significantly reduced total symptom scores compared to placebo at day 7 (p=0.003) and day 21 (p=0.06) 6
Safety Profile
Tolerability
- Loratadine causes minimal sedation compared to first-generation antihistamines (chlorphenamine, hydroxyzine) 4, 5
- Common adverse events at 10 mg daily include somnolence, fatigue, and headache, occurring at rates similar to placebo 5
- In children aged 2-5 years, single and multiple doses were well tolerated with no adverse events occurring more frequently than placebo 3
Cardiovascular Safety
- Unlike some second-generation antihistamines, serious ventricular arrhythmias have not been reported with loratadine 5
- Electrocardiographic parameters were not altered in pediatric studies 3
Special Considerations
Pregnancy and Lactation
- Loratadine is classified as FDA Pregnancy Category B, indicating no evidence of fetal harm in animal studies, though well-controlled human studies are lacking 4
- It is often chosen when antihistamine therapy is necessary during pregnancy due to its safety record 4
Timing of Administration
- Loratadine can be taken without regard to meals 2
- Once-daily dosing improves compliance, particularly in pediatric populations 6
Comparison with Other Antihistamines
- Loratadine has a faster onset (1 hour) compared to astemizole (several days) and comparable efficacy to terfenadine but with longer duration of action 2
- Desloratadine (the active metabolite, available as a separate drug) has similar pharmacokinetics in children, with doses of 1.25 mg for ages 2-5 years and 2.5 mg for ages 6-11 years providing exposure comparable to adult 5 mg doses 7
Common Prescribing Pitfalls
- Do not exceed the recommended daily dose: 10 mg for adults/children ≥6 years or 5 mg for children 2 to <6 years 1
- Do not use liquid formulations interchangeably without checking concentration: The syrup is 1 mg/mL, requiring 10 mL (2 teaspoonfuls) for a 10 mg dose 1
- Do not assume dose adjustments are unnecessary in renal/hepatic impairment: Always consult a physician for these patients 1