Does loratadine have anticholinergic properties?

Loratadine's Anticholinergic Properties

Loratadine does not have significant anticholinergic properties when used at recommended doses. 1

Evidence on Loratadine's Anticholinergic Profile

The 2008 practice parameter on diagnosis and management of rhinitis clearly distinguishes between first-generation and second-generation antihistamines regarding anticholinergic effects:

• First-generation antihistamines (like diphenhydramine, hydroxyzine) have significant anticholinergic effects including:

  • Dryness of mouth and eyes
  • Constipation
  • Inhibition of micturition
  • Increased risk for narrow angle glaucoma 1

• Second-generation antihistamines, including loratadine, have "less or no tendency" for anticholinergic effects 1

The practice parameter specifically states that second-generation antihistamines like loratadine are "generally preferred over first-generation antihistamines" precisely because they lack significant anticholinergic properties 1.

Clinical Studies Supporting Lack of Anticholinergic Effects

Multiple clinical studies have confirmed the absence of anticholinergic effects with loratadine:

• In a comparative study with terfenadine, no anticholinergic side effects were observed in patients receiving loratadine, while dry mouth (an anticholinergic effect) was reported in one terfenadine-treated patient 2

• Another study specifically noted that "no anti-cholinergic effects occurred" with loratadine use 3

Dosage Considerations

It's important to note that loratadine's safety profile is dose-dependent:

• At recommended doses (typically 10mg daily), loratadine does not cause sedation or significant anticholinergic effects 1
• However, at doses exceeding the recommended amount, loratadine may cause sedation 1

Clinical Implications

The lack of significant anticholinergic properties makes loratadine a safer choice for:

• Elderly patients who are more susceptible to adverse anticholinergic effects 1, 4
• Patients with conditions that could be exacerbated by anticholinergic effects, such as:
  • Increased intraocular pressure
  • Benign prostatic hypertrophy
  • Preexisting cognitive impairment 1
  • Urinary retention 4

Practical Prescribing Considerations

When prescribing antihistamines and concerned about anticholinergic burden:

1. Choose second-generation antihistamines like loratadine over first-generation options
2. Adhere to recommended dosing (10mg daily for loratadine)
3. Be particularly cautious in elderly patients, who are more sensitive to anticholinergic effects
4. Consider the patient's total anticholinergic burden from all medications

Pitfalls to Avoid

• Don't confuse loratadine with first-generation antihistamines, which do have significant anticholinergic properties
• Avoid exceeding recommended doses of loratadine, as higher doses may increase risk of side effects
• Be aware that patients with low body mass may experience higher effective doses on a mg/kg basis, potentially increasing risk of side effects 1
• Remember that anticholinergic effects can be cumulative when multiple medications with such properties are used simultaneously 4