What are the guidelines for using Loratidine (Loratadine) in patients with allergies, including those with impaired liver or kidney function, or who are pregnant/breastfeeding?

Loratadine Guidelines for Use in Allergies

Standard Dosing and Administration

Loratadine is dosed at 10 mg once daily for adults and children ≥6 years, and 5 mg once daily for children 2 to under 6 years of age, with dose adjustments required for patients with liver or kidney disease. 1

• For children under 2 years of age, consult a physician before use 1
• The medication provides rapid symptom relief with onset of action within 1 hour and duration of at least 24 hours 2
• Once-daily dosing improves adherence compared to multiple-daily-dosing antihistamines 3

Hepatic and Renal Impairment

Patients with liver or kidney disease must consult a physician before using loratadine, as dose adjustments are necessary. 1

• Loratadine should be used with caution in severe renal impairment 4
• The FDA label explicitly requires medical consultation for consumers with liver or kidney disease before initiating therapy 1

Pregnancy and Breastfeeding

Loratadine is considered safe during pregnancy, including the first trimester, based on large birth registries, case-control studies, and cohort studies showing no significant increase in congenital malformations. 4

• Second-generation antihistamines like loratadine offer the advantage of less sedation compared to first-generation agents like chlorpheniramine, making them preferable from a quality of life perspective 4
• Loratadine is FDA Pregnancy Category B 5
• Avoid combining loratadine with oral decongestants (phenylephrine, pseudoephedrine) during the first trimester due to associations with gastroschisis and small intestinal atresia 4
• The risk of malformations increases when decongestants are combined with acetaminophen or salicylates 4

Clinical Efficacy

Loratadine demonstrates superior efficacy to placebo and comparable effectiveness to other antihistamines for allergic rhinitis and chronic urticaria. 6

• In pediatric allergic rhinitis, loratadine 5-10 mg once daily significantly improved total symptom scores at day 7 and day 21 compared to placebo (p = 0.003, p = 0.06) 7
• Loratadine is faster acting than astemizole and as effective as azatadine, cetirizine, chlorpheniramine, clemastine, hydroxyzine, mequitazine, and terfenadine 6
• No tachyphylaxis develops during treatment, with efficacy maintained over 14-day courses of therapy 8

Safety Profile

Loratadine is well tolerated with sedation occurring less frequently than with first-generation antihistamines, and serious ventricular arrhythmias have not been observed. 6

• At 10 mg daily dosing, commonly reported adverse events include somnolence, fatigue, and headache, occurring at rates similar to placebo 6
• Sedation occurs less frequently with loratadine than with azatadine, cetirizine, chlorpheniramine, clemastine, and mequitazine 6
• Even high-dose exposures (300 mg in a 6-year-old) resulted only in minor elevation of blood pressure and heart rate when managed with supportive care 9
• Loratadine does not impair driving ability or work performance at recommended doses, unlike first-generation antihistamines which increase fatal accident risk by 1.5 times 3

Combination Therapy Considerations

When nighttime symptoms or sleep disturbance are problematic, loratadine can be combined with a sedating antihistamine like hydroxyzine at bedtime. 5

• Use loratadine 10 mg in the morning for daytime coverage without sedation 5
• Add hydroxyzine 10-50 mg at bedtime specifically for patients with urticaria and sleep disturbances 5
• This combination is most useful when sleep disturbance is a significant problem, not primarily for enhanced antihistamine effect 5

Important Clinical Caveats

Loratadine must be discontinued 7 days before oral food challenge testing to avoid interference with interpretation of results. 10

• The 7-day washout period is necessary because loratadine's duration of action and metabolite activity can mask allergic reactions during diagnostic testing 10
• This is longer than the 3-day washout required for fexofenadine or diphenhydramine 10