Salbutamol
Suction and distribution
After ingestion, absorption is high. Bioavailability of the ingested salbutamol is about 50%. Eating reduces the absorption rate, but does not affect bioavailability.
Connection with plasma proteins - 10%. Penetrates through the placental barrier.
Metabolism and excretion
It is subjected to presystemic metabolism in the liver and in the intestinal wall, by means of phenol sulfotransferase is inactivated to 4-o-sulfate ether.
Half-life (T1/2) - 3.8-6 hoursIt is excreted in urine (69-90%), mainly in the form of an inactive phenol sulfate metabolite (60%) for 72 hours and with bile (4%).
Bromhexine
Suction and distribution
When ingested almost completely (99%) is absorbed in the gastrointestinal tract for 30 minutes. Bioavailability is low (the effect of "first passage" through the liver). Penetrates through the placental barrier and the blood-brain barrier (BBB).
Metabolism and excretion
In the liver it is demethylated and oxidized, metabolized to pharmacologically active ambroxol.
T1/2 -15 h (due to slow back diffusion from tissues). It is excreted by the kidneys. With chronic renal failure, excretion of metabolites is impaired. With multiple applications can cumulate.
Guaifenesin
Suction and distribution
Absorption from the gastrointestinal tract is rapid (after 25-30 minutes after ingestion). Penetrates into tissues containing acidic mucopolysaccharides.
Metabolism and excretion
Approximately 60% of the injected drug is metabolized in the liver. T1/2 - 1 h. It is excreted by lungs (with phlegm) and kidneys both in unchanged form and in the form of inactive metabolites.