Colistimethate Sodium Altan

Indications

Colistimethate Sodium (colistin) is an antibiotic kept for serious infections caused by multidrug-resistant Gram-negative bacteria, such as Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella, when other antibiotics cannot be used. It is given by injection for severe infections such as hospital pneumonia, bloodstream and urinary infections, and by inhalation (nebuliser) to control chronic Pseudomonas lung infection in people with cystic fibrosis or bronchiectasis.

How It Works

Colistimethate is converted in the body to colistin, a polymyxin antibiotic. Colistin acts like a detergent on the outer membrane of Gram-negative bacteria, binding to fats in the membrane and making it leaky, so the contents of the bacterial cell escape and the bacteria die.

Dosage and Administration

Colistimethate is given by doctors and nurses in hospital, as an infusion into a vein or an injection into a muscle, usually two or three times a day after a loading dose. For lung infections it may be inhaled through a nebuliser, often started in hospital. Doses are expressed in million international units (MIU), depend on body weight and kidney function, and are given as prescribed. Kidney function and drug levels may be checked during treatment.

Interactions

• Other kidney-harming medicines (aminoglycosides such as Gentamicin and Amikacin, Vancomycin, Amphotericin B, Cisplatin, loop diuretics) increase the risk of kidney damage.
• Muscle relaxants used in anaesthesia, aminoglycosides and some sedatives can increase muscle weakness and breathing problems (neuromuscular blockade).
• Macrolides such as Azithromycin may add to nerve and muscle effects in people with myasthenia gravis.

Contraindications

• Allergy to colistimethate, colistin or polymyxin B.
• Myasthenia gravis (a disease causing muscle weakness).

Side Effects

Common: reduced kidney function, tingling or numbness around the mouth or in the hands and feet, dizziness, slurred speech and itching. Inhaled use can cause cough, chest tightness, wheezing and sore throat. Less common: muscle weakness, confusion and rash.

Get urgent medical help (tell staff at once) for difficulty breathing, severe muscle weakness, greatly reduced urine, swelling of the face or throat, severe wheezing after inhalation, or severe watery or bloody diarrhoea.

Pregnancy and Lactation

Colistimethate crosses the placenta and may harm the baby's kidneys and nerves; it is used in pregnancy only for life-threatening infections when no alternative exists. It passes into breast milk; the doctor will decide whether breastfeeding should continue.

Precautions and Warnings

• Kidney function is monitored and the dose adjusted to it.
• Use with care in people with kidney disease, porphyria or nerve and muscle disorders.
• For inhaled use, a bronchodilator may be given first to prevent wheezing.
• Use only when needed to limit antibiotic resistance.

Overdose

Overdose can cause kidney failure, muscle weakness, breathing failure (apnoea), confusion and seizures. It is treated in hospital with supportive care, which may include breathing support and dialysis.

Therapeutic Class

Antibacterial, polymyxin.

Storage

Hospital medicine: store unopened vials below 25°C, away from light, as directed on the pack; use prepared solutions promptly. Keep out of the reach of children.