What is the most suitable antihistamine to initiate in geriatric patients?

From the Guidelines

For geriatric patients, second-generation antihistamines like loratadine (Claritin) 10mg once daily or fexofenadine (Allegra) 60mg twice daily are generally the best initial choices. These medications provide effective allergy symptom relief with minimal anticholinergic effects and sedation compared to first-generation options 1. Start with the lowest effective dose, and increase if needed. It is essential to avoid first-generation antihistamines like diphenhydramine (Benadryl) in older adults as they cross the blood-brain barrier more readily, causing significant anticholinergic side effects including confusion, urinary retention, constipation, dry mouth, and increased fall risk 1.

When prescribing any antihistamine for geriatric patients, consider renal function adjustments, monitor for side effects, and regularly reassess the need for continued therapy to minimize polypharmacy. Key differences among second-generation antihistamines should be considered, such as their sedative properties: fexofenadine, loratadine, and desloratadine do not cause sedation at recommended doses, while cetirizine may cause sedation at recommended doses 1.

Some essential points to consider when choosing an antihistamine for geriatric patients include:

• The potential for sedation and performance impairment
• The risk of anticholinergic effects, such as dry mouth, constipation, and urinary retention
• The importance of renal function adjustments and monitoring for side effects
• The need to regularly reassess the need for continued therapy to minimize polypharmacy
• The differences in sedative properties among second-generation antihistamines, with fexofenadine, loratadine, and desloratadine being preferred options due to their low sedation risk at recommended doses 1.

From the FDA Drug Label

Clinical studies of fexofenadine hydrochloride tablets and capsules did not include sufficient numbers of subjects aged 65 years and over to determine whether this population responds differently from younger subjects. Other reported clinical experience has not identified differences in responses between the geriatric and younger subjects This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

The most suitable antihistamine to initiate in geriatric patients is not explicitly stated in the label, but fexofenadine can be considered with caution due to the potential for decreased renal function in this population, which may increase the risk of toxic reactions. Key considerations include:

• Dose selection: care should be taken when selecting a dose for geriatric patients
• Renual function monitoring: it may be useful to monitor renal function in geriatric patients taking fexofenadine 2

From the Research

Antihistamine Options for Geriatric Patients

When considering antihistamines for geriatric patients, it's essential to choose options that minimize sedation and other adverse effects. The following points highlight key considerations:

• Second-generation antihistamines, such as loratadine, cetirizine, and fexofenadine, are less likely to produce sedation compared to first-generation antihistamines 3.
• Among these options, fexofenadine is nonsedating, even at high doses, and does not impair psychomotor or cognitive skills 3, 4.
• Cetirizine has a faster onset of action but may cause some sedation, although less than first-generation antihistamines 3, 4.
• Loratadine is also nonsedating but may be less efficacious than cetirizine or fexofenadine 4.

Safety and Efficacy

The safety and efficacy of these antihistamines have been demonstrated in various studies:

• Fexofenadine, loratadine, and cetirizine have excellent safety records, including in special populations such as pediatric and elderly patients 3.
• A study comparing the effects of cetirizine, desloratadine, fexofenadine, levocetirizine, and loratadine on histamine-induced skin reactions found that all these antihistamines significantly reduced the reaction, with levocetirizine being the most effective 5.
• Another study reviewed the literature on antihistamines for acute allergic reactions and concluded that newer antihistamines, such as loratadine, desloratadine, cetirizine, and fexofenadine, provide similar efficacy to first-generation antihistamines but with less sedation 4.

Considerations for Geriatric Patients

When selecting an antihistamine for geriatric patients, it's crucial to consider their individual needs and potential interactions with other medications:

• Geriatric patients may be more susceptible to the sedating effects of antihistamines, which can impair cognitive function and increase the risk of falls 6.
• Therefore, it's essential to choose antihistamines with minimal sedating effects, such as fexofenadine or loratadine, and to monitor patients closely for any adverse effects 3, 4.