Carbocisteine

Carbocisteine (5-carboxymethyl L-cysteine) has been shown in normal and bronchitic animal models to affect the nature and amount of mucus glycoprotein that is secreted by the respiratory tract. An increase in the acid:neutral glycoprotein ratio of the mucus and a transformation of serous cells to mucus cells is known to be the initial response to irritation and will normally be followed by hypersecretion.

The administration of carbocisteine to animals exposed to irritants indicates that the glycoprotein secreted remains normal; administration after exposure indicates that return to the normal state is accelerated.

Studies in humans have demonstrated that carbocisteine reduces goblet cell hyperplasia. Carbocisteine can therefore play a role in the management of disorders characterised by abnormal mucus.

After oral administration, carbocisteine is quickly absorbed; maximum plasma concentration is reached in two hours.

Its bioavailability is low, less than 10% of the administered dose, most likely via intraluminal metabolism with a significant hepatic first pass effect.

Elimination half-life is about 2 hours. Carbocisteine and its metabolites are excreted primarily through the kidneys.

Tests in a wide range of animal species have revealed no significant toxicity. Serious adverse events associated with the use of carbocisteine have not been reported. Even symptomatic adverse events are very rare.