Hydroxyzine – dosage, indications, contraindications, side effects, price

Proven content

Hydroxyzine (hydroxyzinum) is a preparation with a sedative, anxiolytic and itching soothing effect. It inhibits some functions of the central nervous system and blocks the action of histamine secreted by the organism. during allergic reactions. In Poland, it is a prescription drug.

Hydroxyzine is also given for itchy skin with hives, and to relieve atopic eczema or contact eczema. In addition, hydroxyzine is sometimes prescribed to children to relieve anxiety and itching. The dosage of hydroxyzine depends on the doctor’s indications, taking into account the patient’s ailments, age and clinical response.

Hydroxyzine is a prescription drug. Use the online teleconsultation with e-prescription today to get professional help in your ailments.

Hydroxyzine – action

The dominant mechanism of action of hydroxyzine is a potent and selective inverse agonist of the histamine H1 receptor. This action is responsible for its antihistamine and sedative effects. Unlike many other first-generation antihistamines, hydroxyzine has a lower affinity for the muscarinic acetylcholine receptors and therefore has a lower risk of anticholinergic side effects.

In addition to its antihistaminic activity, hydroxyzine has also been shown to be less effective as an antagonist of the serotonin 5-HT2A receptor, the dopamine D2 receptor and the α1-adrenergic receptor. The weak anti-serotonergic activity of hydroxyzine likely underlies its usefulness as an anxiolytic, since other antihistamines without such properties have not been shown to be effective in treating anxiety.

Hydroxyzine readily crosses the blood-brain barrier and has an effect on the central nervous system. A positron emission tomography (PET) study showed that H1 receptor brain involvement was 67,6% with a single 30 mg dose of hydroxyzine. Moreover, subjective sleepiness correlated well with the involvement of the brain H1 receptor. PET studies with antihistamines have shown that H1 receptor brain involvement of more than 50% is associated with a high incidence of somnolence and cognitive decline, while H1 receptor brain involvement of less than 20% is considered unsettling.

Also read: A breakthrough method of delivering drugs to the central nervous system

Hydroxyzine – absorption

Hydroxyzine is rapidly absorbed and distributed after oral and intramuscular administration and is metabolized in the liver; the major metabolite (45%), cetirizine, is formed by the oxidation of the alcohol portion to carboxylic acid by alcohol dehydrogenase, and overall effects are observed within one hour of administration. Higher concentrations are found in the skin than in the plasma. Cetirizine, although less sedative, is not dialysable and has similar antihistamine properties. Other identified metabolites are the N-dealkylated metabolite and the O-dealkylated metabolite 1/16 with a plasma half-life of 59 hours. These pathways are mainly mediated by CYP3A4 and CYP3A5.

Hydroxyzine – excretion

The Tmax (time to peak plasma concentration) of hydroxyzine is approximately 2 hours in both adults and children, and its elimination half-life is approximately 20 hours in adults (mean age 29,3 years) and 7,1 29,3 hour in children. Its elimination half-life is shorter in children compared to adults. In another study, the elimination half-life of hydroxyzine in the elderly was XNUMX hours.

One study found that the elimination half-life of hydroxyzine in adults was only 3 hours, but this could only be due to methodological limitations. Although hydroxyzine has a long elimination half-life and produces an antihistamine for up to 24 hours, the CNS effects of hydroxyzine and other long-term antihistamines appear to diminish after 8 hours.

Hydroxyzine – dosage

The duration of treatment with hydroxyzine should be as short as possible, therefore it is recommended to use the lowest effective dose. The maximum dose for adults and children weighing more than 40 kg should not exceed 100 mg of the active ingredient. In children and adolescents with lower body weight, the daily dose of hydroxyzine of 2 mg per kilogram body weight should not be exceeded.. You should always pay attention to the content of hydroxyzine in one dose (e.g. tablet) of the medicine you buy.

For the elderly, it is recommended not to use hydroxyzine or to reduce the standard adult dose by half.

For adult but sick patients:

1. with hepatic insufficiency the daily dose should be reduced by 33%;
2. With renal insufficiency (moderate or severe form), the usual dose should be reduced.

In the case of children under 6 years of age, the use of an oral syrup is sometimes recommended (due to the risk of choking).

Hydroxyzine can also be administered intramuscularly. As such, usually:

1. in adults, for symptomatic treatment of anxiety, the dose should be between 25 and 100 mg (a day);
2. in children with a sedative effect, the dose should be 0,6 mg / kg to 1 mg / kg (daily).

As in the case of oral administration, the doses of intramuscular hydroxyzine depend on the target group of patients, i.e. the elderly are treated with a lower dose than usually recommended. In the case of impaired liver and / or kidney function, a single and daily dose depends on the individual response of the patient.

If an overdose has occurred, medical attention must be sought – the signaling symptoms are, inter alia, feeling of extreme drowsiness and impending fainting, nausea, vomiting. As with the use of other sedative and anti-anxiety medications, high caution is required in taking hydroxyzine.

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The sedative effect of hydroxyzine is observed approx. 30–45 minutes after taking the tablets and 5–10 minutes after drinking the syrup. You need to wait an average of an hour for the antihistamine effect of the substance.

See also: Calming tablets – composition, action, contraindications

Contraindications are also some diseases and conditions, e.g. porphyria, glaucoma, impaired digestive tract peristalsis, bladder outflow disorders, acquired or congenital prolongation of the QT interval, cardiovascular disease, significant electrolyte disturbances (hypokalemia, hypomagnesemia), bradycardia.

Sudden cardiac death in the patient’s family and the use of drugs known to prolong the QT interval and / or cause torsades de pointes in the patient’s family at the same time also contraindicate the use of hydroxyzine.

Before issuing a prescription, the physician should obtain information about the patient’s health. The occurrence of symptoms and ailments such as:

1. seizures
2. kidney and liver diseases,
3. Heart arythmia,
4. prostate enlargement,
5. thyroid disease
6. hypertension,
7. asthma,
8. breathing problems,
9. ulcers
10. bowel obstruction.

Read also: Antihistamines – action, types of drugs, side effects

Hydroxyzine – precautions

In the elderly, hydroxyzine may impair cognitive function and cause more side effects, so it is important to strictly follow the dosage recommendations. You should stop taking hydroxyzine and consult a specialist if you experience disturbing symptoms, such as:

1. seizures
2. a feeling of confusion in the head,
3. heart problems; 
4. tremors and muscle spasms around the eyes, tongue, jaw and neck.

Patients prone to convulsions should take special care when using hydroxyzine (the occurrence of seizures in children has been reported more frequently than in adults). An increased risk of side effects also occurs in people with myasthenia gravis and obstructed outflow of urine from the bladder, glaucoma, impaired gastrointestinal motility, dementia, dementia (in such people hydroxyzine has an anticholinergic effect).

Young children are more likely to experience side effects from the central nervous system (CNS).

People suffering from renal insufficiency should be especially careful, because one of the metabolites of hydroxyzine is ceritizine (an active metabolite). The clearance of cetirizine is reduced in patients with known renal impairment.

Some patients experienced torsades de pointes and QT prolongation. Accompanying factors were also electrolyte and drug disturbances, which could have contributed to the occurrence of these disturbances.

Hydroxyzine in solution for injection is used intramuscularly, it cannot be used in subcutaneous, intravenous or intraarterial applications.

Caution should be exercised when using hydroxyzine in patients with asthma.

When using hydroxyzine, you should not drive motor vehicles and perform activities requiring reflexes and high precision.

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Hydroxyzine – possible side effects

Potential side effects of taking hydroxyzine include headache, lethargy, and dry mouth (the most common). The less frequent side effects include symptoms from:

1. nervous system (drowsiness or difficulty falling asleep, fatigue, depression, headache, nervousness),
2. digestive system (nausea, diarrhea, stomach pain, increase in appetite and weight gain),
3. cardiovascular system (hypotension, palpitations, edema),
4. dermatological problems (rash, photosensitivity),
5. difficult urination,
6. excessive sweating,
7. blurred vision,
8. problems with the respiratory system.

An overdose of hydroxyzine may lead to vomiting, tachycardia (tachycardia), fever, drowsiness, excessive sedation, and disturbed coordination of movements, consciousness and breathing. Other possible reactions include seizures, confusion and hallucinations, as well as abnormal heart beats and cardiovascular collapse. The type and severity of symptoms depends on how much the recommended dose of the preparation has been exceeded.

Also, remember to avoid drinking alcohol while you are taking hydroxyzine. Hydroxyzine and alcohol depress the CNS, which may result in: drowsiness, excessive sedation, and decreased psychomotor skills.

Interactions of hydroxyzine with other drugs

Before taking hydroxyzine, it is absolutely necessary to inform the doctor about the medications you are taking. Hydroxyzine enhances the effect of drugs depressing the central nervous system, therefore their doses should be reduced. It is an active substance that also has a potentiating effect on alcohol and anticoagulants.

Hydroxyzine used with tricyclic antidepressants may increase their cardiotoxicity. It is not recommended to use hydroxyzine together with cholinolytic preparations. The spectrum of likely interactions is wide, therefore it is necessary to discuss the dosages used with the specialist.

It should also be remembered that hydroxyzine may affect the results of some tests, including allergy tests and methacholine provocation tests.

Check: Non-prescription and prescription sedatives – characteristics and effects

Hydroxyzine – driving vehicles

Hydroxyzine may impair psychomotor performance and cause fatigue, dizziness, sedation, and visual disturbances, and thus have a moderate to severe influence on the ability, reaction speed and concentration, especially in high doses and / or in the case of concomitant use of alcohol or sedatives.

Hydroxyzine – pregnancy and breastfeeding

Hydroxyzine crosses the placental barrier and reaches a higher concentration in the body of the fetus than in the mother.

Hydroxyzine administered in late pregnancy and / or labor may cause hypotension, movement disorders (including extrapyramidal disorders), clonic movements, CNS depression, wetting retention, or neonatal hypoxia.

Regarding the effects of hydroxyzine on lactation, cetirizine, the main (active) metabolite of hydroxyzine, passes into breast milk. Breast-feeding should be discontinued if the use of hydroxyzine is necessary.