Colistimethate Sodium (Inhaled)

How it works

Colistimethate is a prodrug that converts to colistin, which disrupts the Gram-negative bacterial outer membrane to produce a bactericidal effect against Pseudomonas. Delivery directly to the lungs concentrates drug at the site of infection.

Prescribing in practice

• Inhalation can provoke bronchospasm and chest tightness, so the first dose should be given under supervision with assessment of lung function, and a bronchodilator is usually given beforehand.
• Each nebuliser dose must be freshly reconstituted and used promptly, and patients should be trained in correct device and inhaler technique.
• Avoid in known polymyxin hypersensitivity and use cautiously where there is significant haemoptysis.

Monitoring

Assess lung function around the first dose for bronchoconstriction and monitor respiratory tolerance and sputum response over treatment.

Counselling the patient

• Use a bronchodilator first if advised, and take any other inhaled treatments in the recommended order.
• Report wheeze, cough, or chest tightness after inhaling.
• Clean and maintain your nebuliser or inhaler device as instructed.

Evidence & guidelines

Inhaled colistimethate is established in UK cystic fibrosis and bronchiectasis practice for suppression of chronic Pseudomonas aeruginosa airway infection.