Products
Hydroxyzine is commercially available in the form of film-coated tablets and as a syrup (Atarax). It has been approved in many countries since 1956.
Structure and properties
Hydroxyzine (C21H27ClN2O2, Mr = 374.9 g/mol) is a piperazine derivative. It is present in drugs as hydroxyzine hydrochloride, a white crystalline powder that is readily soluble in water. It is oxidized in the organism to the major metabolite cetirizine, among others, which is also commercially available (Zyrtec, generics).
Effects
Hydroxyzine (ATC N05BB01) has sedative, depressant, antianxiety, antihistamine, anticholinergic, anticonvulsant, antiemetic, and antiallergic properties. The effects are due in part to antagonism at histamine H1 receptors and anticholinergic properties. It is a 1st generation nonselective antihistamine.
Indications
For the treatment of psychovegetative disorders (such as hyperexcitability, tension, nervousness, insomnia, anticipatory anxiety), allergic disorders, and as a sedative before surgical procedures.
Dosage
According to the professional information. The tablets are usually taken in the morning and evening.
Contraindications
- Hypersensitivity
- Severe hepatic or renal insufficiency
- Prostate enlargement with residual urine formation
- Narrow-angle glaucoma
- Porphyria
- Patients with pre-existing QT interval prolongation.
- Treatment with MAO inhibitors
- Pregnancy and lactation
Full precautions can be found in the drug label.
Interactions
Hydroxyzine is metabolized by CYP3A and alcohol dehydrogenase and is an inhibitor of CYP2D6. Drug interactions are possible with alcohol, central depressant drugs, MAO inhibitors, antihypertensives, betahistine, parasympathomimetics, epinephrine, phenytoin, and cimetidine, among others.
Adverse effects
The most common possible adverse effects include drowsiness, headache, dullness, and dry mouth. Hydroxyzine is less selective than modern second-generation antihistamines and therefore may cause more side effects.
