The pharmacokinetics of levocetirizine is linear and practically does not differ from the properties of cetirizine.
When taken orally, the medicine is absorbed intensively and quickly. At the same time, the degree of absorption does not change with the use of food and the size of the dose taken, although a decrease in the peak concentration and an extension of the time of its attainment are observed. The level of bioavailability is 100%.
In 5% of patients treated, the drug begins 12 minutes after a single use, and the rest 95% after 0.5-1 hour. Plasma peak level is observed after 50 minutes after oral single dose of drug, and its duration is 2 days. The peak value is 270 ng / ml for a single dose, as well as 308 ng / ml for 5 mg of the drug again.
There is no information about the distribution of the drug inside the tissues and its passage through the BBB. Tests have shown that the highest concentration is observed in the kidneys with the liver, and the lowest - inside the tissues of the central nervous system. The distribution volume is 0.4 l / kg. The synthesis of a substance with a plasma protein is 90%.
Inside the body, approximately 14% of levocetirizine is metabolized. During this process, there is a connection with taurine, oxidation, also N- and O-dealkylation. The latter are carried out with the help of the hemoprotein CYP 3A4, while the oxidative processes are assisted by numerous or unknown isoforms of the CYP element.
Levocetirizine has no effect on the activity of hemoprotein isoenzymes 1A2 with 2C9, as well as 2C19 and 2D6, together with 2E1 and 3A4 at rates that exceed the maximum level by oral intake of 5 mg of the drug at times. Since the metabolism is quite low, and the ability to inhibit this process is absent, the likelihood of interaction of levocetirizine and other medicinal components is extremely small.
Excretion of the substance is mainly performed by filtration of glomeruli and active secretion of the tubules. The half-life from plasma (adults) is 7.9 + 1.9 hours. This segment is shorter in children. The total clearance rate (adults) is 0.63 ml / minute / kg. Excretion of the active ingredient and decay products mainly occurs in the urine (the average is 85.4% of the dose used). Only 12.9% of the substance is excreted with feces.
The apparent coefficient of purification of levocetirizine in the body is in correlation with the KK index. Because of this, people with severe or moderate degree of disorders in the work of the kidneys need to select the intervals between the use of levocetirizine, given the QC values. In the presence of anuria in the final stage of the terminal stage of renal pathology, the overall level of clearance in such people, in comparison with similar indicators in persons without similar disorders, is reduced by approximately 80%.
The amount of active substance released during hemodialysis (the standard procedure lasting 4 hours) is equal to <10%.