VPT 311: General and Systemic Veterinary Pharmacology (2+1)

MUCOLYTICS 

• Mucolytics assist in preventing or removing mucus plugs that cause atelectasis and this may progress to bronchiectasis.Sodium acetylcysteine solution 20% is inhaled in the form of spray or aerosol. The sulphydryl group of acetylcysteine breaks disulphide bonds in the glycoproteins in exudates. The drug shares with DMSO the property of scavenging hydroxyl radicals.
• It causes mild irritation to the respiratory tract, but its otherwise safe and successful in effecting the rapid liquefaction of mucopurulent materials. 
• Several minutes of exposure repeated two or three times a day, perhaps with positive pressure, gives the best results.
• Acetylcysteine is also used as an intravenous antidote for acetaminophen toxicity in cats.
•  Bromhexine is of value in achieving liquefaction and improved flow characteristics of mucus by increasing its volume and decreasing its viscidity.
• It is available in solution or as a powder, alone or mixed with antibacterial agents.
• Bromhexine brings about an increase in the content of immunboglobulin and oxytetracycline in bronchial secretions, presumably by increasing membrane permeability.
• The drug improves lysosomal function and that lysosomal enzymes hydrolyse the mucopolysaccharide fibers of mucous.
• The dose rate is 1 mg/kg body weight twice daily in small animals and 0.1 – 0.25 mg/kg body weight in horses, either orally or parenterally, for 7 days.
• Dembrexine is of value in treating equines and for its action on the secretory activity of serous glandular cells in respiratory mucosae.
• The mucus of modified composition and hence decreased viscosity is secreted.
• Such mucus is more amenable to mucociliary clearance and cause speedier reduction in coughing and cessation of mucus production in treated animals.
• The product can be administered intravenously or by mouth at a dose rate of 0.3-0.5mg/kg twice daily for 10 days.