Indications
Colistin (given as colistimethate sodium) is an antibiotic used in hospital for serious infections caused by Gram-negative bacteria that are resistant to most other antibiotics, such as multidrug-resistant Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae. These include pneumonia (including ventilator-associated), bloodstream infections, urinary tract infections and other severe hospital infections. It is usually a last-resort option.
How It Works
Colistin belongs to the polymyxin group of antibiotics. It binds to the outer membrane of Gram-negative bacteria and disrupts it like a detergent, causing the contents of the bacterial cell to leak out and the bacteria to die.
Dosage and Administration
Colistin injection is given only in hospital by a doctor or nurse, into a vein (by slow injection or infusion) or into a muscle. Doses are expressed in million international units (MIU) and are calculated by body weight and kidney function, often with a loading dose first, as prescribed. A nebulised form may be used for some chest infections. It is often combined with another antibiotic.
Interactions
Other medicines that can harm the kidneys, such as aminoglycosides (Gentamicin, Amikacin), Vancomycin, Amphotericin B, Cisplatin and loop diuretics, increase the risk of kidney damage. Muscle relaxants used in anaesthesia and aminoglycosides may increase nerve and muscle blockade, which can weaken breathing. Tell the doctor about all medicines.
Contraindications
- Allergy to colistin or polymyxin B.
- Myasthenia gravis, unless the doctor decides it is essential.
Side Effects
The main side effects are kidney damage (reduced urine output, rising creatinine) and nerve effects such as tingling around the mouth or in the hands and feet, dizziness, confusion, slurred speech, vision problems and muscle weakness. Pain at the injection site, rash and itching can occur. Rarely, it can cause breathing to stop (respiratory arrest) because of muscle weakness. Inhaled forms may cause cough or chest tightness.
Tell the nurse or doctor immediately if you have difficulty breathing, severe weakness, much less urine, severe numbness or tingling, confusion, or signs of an allergic reaction such as swelling or a widespread rash. Severe diarrhoea during or after treatment should also be reported.
Pregnancy and Lactation
Colistin crosses the placenta and may harm the baby’s kidneys or nerves. It is used in pregnancy only for life-threatening infections when no safer option exists. It passes into breast milk; the doctor will advise whether breastfeeding should pause.
Precautions and Warnings
Kidney function is checked before and regularly during treatment, and the dose is adjusted if kidney function changes. Use with care in people with kidney disease, porphyria, myasthenia gravis or other nerve and muscle disorders, and in older people. Patients are watched for breathing problems. It should not be used for minor infections, to reduce the spread of resistance.
Overdose
Overdose can cause kidney failure, muscle weakness and breathing failure. The infusion is stopped and supportive care, including breathing support, is given in hospital; haemodialysis may help remove some of the medicine.
Therapeutic Class
Polymyxin antibiotic.
Storage
Store unopened vials below 25°C, away from light, as directed on the pack. Use prepared solutions promptly as advised by the pharmacy. Keep out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.