Indications
Cetirizine is mainly used in the treatment of existing allergies or skin diseases. For example, cetirizine can be used for hay fever (allergic rhinitis) and thus treats the typical symptoms such as itching, a runny nose, reddened eyes, lacrimation and sneezing. In chronic urticaria, cetirizine can help to reduce the symptoms such as reddened skin and itching and is approved as an active ingredient for the treatment of these symptoms in existing urticaria. The dilative effect on the muscles of the bronchi can be used in supportive therapy for chronic asthma. Since chronic bronchial asthma is characterized by narrow bronchial passages and the associated shortness of breath, cetirizine can be used to support the treatment of these symptoms.
Metabolism
The so-called pharmacokinetics describes how a certain active substance is absorbed, distributed and finally degraded and excreted in the body. The active ingredient is usually taken orally and then first reaches the gastrointestinal tract, where it is absorbed through the mucous membrane and enters the blood. The maximum concentration of cetirizine in the blood is reached after about 1-2 hours after taking the drug.
The maximum concentration can be reached even faster if a liquid dosage form, such as drops or juice, is chosen instead of the tablet form. About 60% of the active substance is excreted unchanged via the kidneys and can thus be found in the urine. About 10 hours after taking the active substance, only 50% of the amount is still present in the blood.
A so-called “steady state”, in which approximately the same amount of the active substance is constantly present in the blood, is reached after three days with a daily intake of 10 mg cetirizine. Pharmacokinetics play an important role in the intake of cetirizine in people with impaired kidney function. This also applies to older people, as kidney function decreases over time.
Since cetirizine is excreted via the kidneys, the active substance remains in the blood for longer if renal function is impaired. This can and should be corrected in this group of people with an adjusted, lower dose. In any case, it is important that if impaired renal function is known, the treating physician is informed about the previous illness before taking the active substance cetirizine.
The pharmacokinetics of the active substance in children do not differ significantly from those in adults. However, the dose should be adjusted to body weight. For example, children usually take a dose of 5mg a day.
It is not recommended for children under two years of age. Interactions between cetirizine and other drugs or substances are not known. The effect of alcohol is also not increased by taking cetirizine. Taking cetirizine and other foods at the same time slows down the absorption of the active substance.
