From the Guidelines
Vistaril (hydroxyzine) is considered an anticholinergic medication, albeit with mild anticholinergic properties compared to other medications like diphenhydramine or tricyclic antidepressants. While its primary mechanism of action is as an antihistamine that blocks H1 receptors, it does possess some anticholinergic properties, which can include dry mouth, blurred vision, urinary retention, and constipation, particularly at higher doses 1. This occurs because hydroxyzine partially blocks muscarinic acetylcholine receptors in various tissues throughout the body.
Key Points to Consider
- The anticholinergic effects of Vistaril contribute to some of its therapeutic effects, such as reducing secretions and helping with nausea, but also account for some of its side effects 1.
- For elderly patients or those with conditions like glaucoma, prostatic hyperplasia, or cognitive impairment, the anticholinergic burden of Vistaril should be considered when prescribing, as these patients may be more sensitive to these effects 1.
- The use of anticholinergic medications like Vistaril in older adults can lead to a decline in cognition, functional status, and activities of daily living (ADL) scores, and is associated with an increased risk of injurious falls, episodes of confusion or delirium, visits to the emergency department, and hospitalizations 1.
Clinical Implications
- When prescribing Vistaril, particularly to elderly patients or those with certain medical conditions, it is essential to weigh the potential benefits against the potential risks associated with its anticholinergic properties 1.
- Consideration should be given to alternative medications with fewer anticholinergic effects, especially in patients who are more susceptible to these adverse effects 1.
From the FDA Drug Label
Anticholinergic: Dry mouth
- Anticholinergic effects are present, as evidenced by the side effect of dry mouth.
- The presence of anticholinergic effects, such as dry mouth, indicates that Vistaril (hydroxyzine) has anticholinergic properties 2.
From the Research
Anticholinergic Properties of Vistaril (Hydroxyzine)
- Vistaril (hydroxyzine) is an antihistamine medication that has been used in the treatment of anxiety 3.
- While hydroxyzine is not primarily classified as an anticholinergic, it does possess some anticholinergic properties 4.
- A study on sedating antihistamines, including hydroxyzine, noted that these substances have antihistaminergic and anticholinergic effects 4.
- Another study found that hydroxyzine, along with other anxiolytics, inhibited acetylcholine-induced contractions in rat detrusor smooth muscle, suggesting some anticholinergic activity 5.
- However, the same study noted that this inhibition occurred at concentrations that substantially exceeded clinically achievable blood levels 5.
Comparison with Other Anticholinergic Agents
- Hydroxyzine was compared to other anxiolytic agents, including benzodiazepines and buspirone, and found to be equivalent in terms of efficacy, acceptability, and tolerability 3.
- A review of anticholinergic drugs noted that many commonly used medications, including antihistamines, have mild anticholinergic properties 6, 7.
- The cumulative effects of using multiple drugs with mild anticholinergic properties, such as hydroxyzine, may lead to increased falls risk in older adults 7.
Clinical Implications
- Prescribers should be vigilant for adverse anticholinergic effects, particularly in older patients, when using hydroxyzine or other medications with anticholinergic properties 6.
- The Anticholinergic Drug Scale and tables listing drugs with known anticholinergic properties may help guide clinical decision-making to reduce anticholinergic burden 6.
- When prescribing hydroxyzine, consideration should be given to its pharmacological properties, including antihistaminergic and anticholinergic effects, as well as the risks of severe intoxication in case of overdose 4.