At a glance......
- 1 Mechanism of Action of Hydroxyzine
- 2 Indications of Hydroxyzine
- 3 Contra-Indications of Hydroxyzine
- 4 Side Effects of Hydroxyzine
- 5 Drug Interactions of Hydroxyzine
- 6 Pregnancy & Lactation of Hydroxyzine
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Hydroxyzine is a piperazine derivative with antihistamine, antiemetic, and anxiolytic properties. Hydroxyzine’s antihistaminic effect is due to its metabolite, cetirizine, a potent H1 receptor antagonist and selective inhibitor of peripheral H1 receptors. This agent competes with histamine for binding at H1-receptor sites on the effector cell surface. The sedative properties of hydroxyzine occur as a result of the suppression of certain subcortical regions of the brain. Secondary to its central anticholinergic actions, hydroxyzine may be effective as an antiemetic.
Hydroxyzine is a first-generation antihistamine that is used largely for symptoms of itching, nausea, anxiety, and tension. Hydroxyzine has not been linked to instances of clinically apparent acute liver injury.
Mechanism of Action of Hydroxyzine
Hydroxyzine competes with histamine for binding at H1-receptor sites on the effector cell surface, resulting in suppression of histaminic edema, flare, and pruritus. The sedative properties of hydroxyzine occur at the subcortical level of the CNS. Secondary to its central anticholinergic actions, hydroxyzine may be effective as an antiemetic.
The effects of the drug hydroxyzine on the activities of the rat liver monoamine oxidases and the membrane-bound and soluble forms of bovine semicarbazide-sensitive amine oxidase were studied. Hydroxyzine was found to be a competitive inhibitor of MAO-B (Ki – 38 microM), whereas it had a low potency towards MAO-A (IC50 > 630 microM). Although it was a relatively potent competitive inhibitor of bovine plasma SSAO (Ki approximately 1.5 microM), it was a weak inhibitor of the membrane-bound form of the enzyme from bovine lung (IC50 approximately 1 mM). These findings extend our knowledge of the drug binding capabilities of the amine oxidases and suggest that these interactions may contribute to the complex actions of this drug.
Indications of Hydroxyzine
- Allergic Urticaria
- Interstitial Cystitis
- Alcohol Withdrawal Syndrome
- Psychomotor Agitation
- Acute Anxiety
- For symptomatic relief of anxiety and tension associated with psychoneurosis and as an adjunct in organic disease states in which anxiety is manifested. Useful in the management of pruritus due to allergic conditions such as chronic urticaria.
Contra-Indications of Hydroxyzine
- Low amount of magnesium in the blood
- Low amount of potassium in the blood
- Wide-angle glaucoma
- Closed-angle glaucoma
- Heart attack
- Prolonged QT interval on EKG
- Chronic heart failure
- Abnormal EKG with QT changes from birth
- Stenosing peptic ulcer
- Narrowing of opening between stomach and small intestine
- Blockage of urinary bladder
- Enlarged prostate
- Cannot empty bladder
Side Effects of Hydroxyzine
The most common
- Nausea and vomiting
- Severe stomach ache
- epigastric pain,
- fainting, fast or pounding heartbeats;
- Chest pain or discomfort
- difficulty with swallowing
- fast heartbeat
- hives, itching, or skin rash
- irregular or slow heart rate
- puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
- shortness of breath
- tightness in the chest
- unusual tiredness or weakness
Drug Interactions of Hydroxyzine
- “azole” antifungals (e.g., itraconazole, ketoconazole, voriconazole)
- barbiturates (e.g., butalbital, pentobarbital, phenobarbital)
- sulfonamide antibiotics (e.g., sulfadiazine, sulfamethoxazole, sulfisoxazole)
Hydroxyzine should not be used during early pregnancy. It should be used during later pregnancy only if the potential benefits outweigh the risks.
It is not known if hydroxyzine passes into breast milk. Hydroxyzine should not be used by breastfeeding mothers.