An inhaled antibiotic for Pseudomonas in cystic fibrosis
Colistimethate
An inhaled (or hospital intravenous) antibiotic used against Pseudomonas lung infection in cystic fibrosis.
What is Colistimethate?
Colistimethate is an antibiotic used in cystic fibrosis to control infection with a germ called Pseudomonas, which often settles in the lungs. It is usually breathed in — either as a dry powder or through a nebuliser — to deliver it straight to the lungs, and it can also be given by drip in hospital for serious infections. Inhaling it can cause cough, chest tightness or wheeze, so a reliever inhaler is sometimes used first. The intravenous form can affect the kidneys and nerves. It is part of specialist cystic fibrosis care.
Education and reference only. This is a plain-language guide to Colistimethate — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Colistimethate is an antibiotic used to treat and control Pseudomonas aeruginosa, a bacterium that commonly infects the lungs in cystic fibrosis and is hard to clear. In cystic fibrosis it is most often given by inhalation — as a dry powder from an inhaler device or as a liquid through a nebuliser — so that high amounts reach the lungs with less effect on the rest of the body. In hospital it can also be given into a vein for severe infections. It is prescribed and supervised by a specialist cystic fibrosis team.
How it works
Colistimethate is converted in the body into colistin, an antibiotic that damages the outer wall of certain bacteria, including Pseudomonas, killing them. By breathing it in, the medicine is delivered straight to the airways where the infection lives, keeping the bacteria under control and helping protect lung function. Long-term inhaled use aims to suppress chronic Pseudomonas infection rather than always cure it outright. When given into a vein in hospital, it treats more serious infection but reaches the whole body, which is why it can affect the kidneys and nerves.
Company & origin
Originated / developed by: Generic (also branded).
An antibiotic used in the UK, usually inhaled, to control Pseudomonas lung infection in people with cystic fibrosis.
Practical use
How to take Colistimethate
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by inhalation as directed — either as a dry powder through the inhaler device or freshly prepared through your nebuliser.
- If advised, use your reliever (bronchodilator) inhaler beforehand to reduce coughing, chest tightness or wheeze.
- Do not mix the nebulised form with other medicines in the same chamber, and follow the order your team gives for your treatments.
- Learn and use the correct technique for the dry-powder inhaler, and clean nebuliser equipment as instructed.
- Tell your team if you get marked wheeze, breathlessness or chest tightness after a dose.
- If you receive the intravenous form in hospital, report any tingling, numbness or changes in passing urine.
Weighing it up
Advantages & disadvantages of Colistimethate
Advantages
- Delivered by inhalation straight to the lungs, controlling Pseudomonas with less effect on the rest of the body.
- Helps suppress chronic lung infection and protect lung function over time.
- Available as a dry-powder inhaler or nebuliser solution, and as an intravenous option for severe infection.
Disadvantages
- Inhaling it can cause cough, chest tightness or wheeze, sometimes needing a reliever inhaler first.
- Needs careful preparation, inhaler technique and equipment cleaning.
- The intravenous form can affect the kidneys and nerves, so it needs monitoring in hospital.
Practical use
Good to know
Colistimethate is mainly used to keep Pseudomonas lung infection under control in cystic fibrosis. Breathing it in can irritate the airways and cause cough, chest tightness or wheeze, so your team may advise using a reliever (bronchodilator) inhaler first and may check your breathing before and after the first dose. With the nebulised form, it must be freshly prepared and not mixed with other nebuliser medicines, and the dry-powder inhaler has its own technique to learn. The intravenous form used in hospital can affect the kidneys and nerves (causing tingling or numbness), so kidney function is monitored. As with all antibiotics, finish courses as directed and keep up the rest of your cystic fibrosis care.
Who should not take it / use with caution
- Anyone who has had a serious allergic reaction to colistimethate (colistin) or related antibiotics (polymyxins).
- It is used with extra care and monitoring in people with kidney problems, especially the intravenous form.
- Inhaled use is reviewed if it consistently triggers marked wheeze or breathlessness.
Monitoring
- Checking breathing before and after early inhaled doses, and watching for wheeze or chest tightness.
- Monitoring kidney function and nerve symptoms when the intravenous form is used.
- Reviewing lung infection control, lung function and inhaler or nebuliser technique.
Side effects
- Cough, chest tightness, wheeze, sore throat or a change in voice with the inhaled form.
- An unpleasant taste with the dry powder, and sometimes breathlessness after a dose.
- With the intravenous form, effects on the kidneys and nerves (such as tingling or numbness).
Key interactions
- Care is needed with other medicines that can affect the kidneys, especially when given into a vein.
- It should not be mixed with other medicines in the nebuliser chamber.
- Tell your cystic fibrosis team and pharmacist about all the medicines you take, including other antibiotics.
Available as: A dry-powder inhaler, a nebuliser solution, and an intravenous form used in hospital.
Answers
Colistimethate: frequently asked questions
What is colistimethate used for in cystic fibrosis?
It is an antibiotic used to control Pseudomonas, a germ that commonly infects the lungs, and is usually breathed in to deliver it straight to the chest.
Why do I cough or feel tight-chested after inhaling it?
Inhaling it can irritate the airways; your team may advise using a reliever inhaler first and may check your breathing around early doses.
Can I mix the nebulised form with my other medicines?
No, it should be freshly prepared and not mixed with other medicines in the same chamber; follow the order your team gives.
Is the drip form different?
Yes, the intravenous form is used in hospital for more serious infection and reaches the whole body, so it can affect the kidneys and nerves and needs monitoring.
Do I keep taking it long term?
Inhaled colistimethate is often used long term to keep chronic Pseudomonas infection under control; follow your team's plan and report any problems.
Authoritative sources
- BNF
- NICE CKS
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