Ibuprofen.
Absorption is high, quickly and almost completely absorbed from the gastrointestinal tract (GIT). The time to reach the maximum concentration (TCmax) after ingestion is about 1-2 hours. The connection with blood plasma proteins is more than 90%. Half-life (T1 / 2) - about 2 hours Slowly penetrates the joint cavity, accumulates in the synovial fluid, creating higher concentrations in it than in the blood plasma. After absorption, about 60% of the pharmacologically inactive R-form is slowly transformed into an active S-form. Exposed to metabolism. More than 90% is excreted by the kidneys (unchanged not more than 1%) and, to a lesser extent, with bile in the form of metabolites and their conjugates.
Paracetamol.
Absorption is high, the association with plasma proteins is less than 10% and slightly increases with an overdose. Sulfate and glucuronide metabolites do not bind to plasma proteins even at relatively high concentrations. The value of Cmax is 5-20 μg / ml, TCmax is 0.5-2 hours. It is evenly distributed in the liquid medium of the body. Penetrates through the blood-brain barrier.
About 90-95% of paracetamol is metabolized in the liver with the formation of inactive conjugates with glucuronic acid (60%), taurine (35%) and cysteine (3%), as well as a small amount of hydroxylated and deacetylated metabolites. A small part of the preparation is hydroxylated by microsomal enzymes with the formation of highly active N-acetyl-l-benzoquinonimine, which binds to the sulfhydryl groups of glutathione. When depletion of glutathione stores in the liver (with an overdose) enzyme systems of hepatocytes can be blocked, leading to the development of their necrosis.
T1 / 2 - 2-3 hours. In patients with cirrhosis of the liver, T1 / 2 slightly increases. In elderly patients the clearance of the drug decreases and T1 / 2 increases. It is excreted by the kidneys, mainly in the form of glucuronide and sulfate conjugates (less than 5% in unchanged form). Breast milk penetrates less than 1% of the accepted dose of paracetamol. In children, the ability to form conjugates with glucuronic acid is lower than in adults.