Hydroxyzine doses
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Hydroxyzine Doses: Efficacy, Safety, and Side Effects
Introduction to Hydroxyzine
Hydroxyzine is an antihistamine commonly used for its sedative and anti-anxiety properties. It is also effective in treating allergic reactions and pruritus. This article synthesizes research findings on the efficacy, safety, and side effects of various hydroxyzine doses.
Efficacy of Hydroxyzine in Treating Anxiety and Allergies
Generalized Anxiety Disorder (GAD)
Hydroxyzine has been shown to be effective in treating Generalized Anxiety Disorder (GAD). A study involving 334 outpatients demonstrated that a daily dose of 50 mg hydroxyzine significantly reduced anxiety symptoms compared to placebo, as measured by the Hamilton Rating Scale for Anxiety (HAM-A) . The study also found that hydroxyzine was as effective as bromazepam, a commonly prescribed benzodiazepine, but with fewer side effects like drowsiness .
Allergic Reactions and Pruritus
Hydroxyzine is effective in suppressing histamine-induced wheals, flares, and pruritus. A single dose of 0.7 mg/kg (approximately 39 mg) was found to significantly reduce these symptoms for up to 36 hours . Another study confirmed that hydroxyzine, at doses of 25 mg, effectively suppressed skin wheal responses to histamine, comparable to cetirizine, a non-sedating antihistamine .
Seasonal Allergic Rhinitis
In a study during the ragweed season, hydroxyzine at doses up to 150 mg/day was effective in reducing symptoms of seasonal allergic rhinitis. Patients reported fewer days with severe symptoms compared to those on placebo, although initial side effects like drowsiness and dry mouth were noted .
Safety and Side Effects of Hydroxyzine
Central Nervous System (CNS) Effects
Hydroxyzine is known to cause CNS effects such as drowsiness and impaired psychomotor performance. A study comparing hydroxyzine (25 mg) with cetirizine found that hydroxyzine significantly affected CNS parameters, including critical flicker frequency and Stroop word testing, while cetirizine did not . Another study showed that hydroxyzine (50 mg) significantly impaired driving performance, as measured by the standard deviation of lateral position (SDLP) in a highway driving test .
Cardiovascular Effects
Hydroxyzine has been observed to cause a transient fall in arterial blood pressure and reduce the incidence of ventricular arrhythmias in animal studies. It also increased coronary flow and dilated femoral blood vessels .
Sedation in Pediatric Patients
In pediatric dental patients, hydroxyzine at a dose of 3.7 mg/kg was effective for sedation when combined with nitrous oxide. However, administering an additional 20 mg dose 24 hours preoperatively did not provide any significant benefit .
Reaction Times and Cognitive Performance
Hydroxyzine (25 mg twice daily) significantly prolonged both simple and choice reaction times in healthy adults, indicating impaired cognitive performance. This effect was not observed with terfenadine, a non-sedating antihistamine .
Conclusion
Hydroxyzine is effective in treating anxiety, allergic reactions, and pruritus at various doses. However, its use is associated with significant CNS side effects, including drowsiness and impaired psychomotor performance. While it is a viable alternative to benzodiazepines for anxiety treatment, caution is advised due to its sedative properties, especially in activities requiring alertness, such as driving. Further research comparing hydroxyzine with newer, non-sedating antihistamines could provide additional insights into its optimal use.
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