Indications
Polymyxin (Polymyxin B) is an antibiotic. In the products listed here it is used on the skin, eyes or ears, usually combined with other antibiotics such as Neomycin and Bacitracin, and sometimes with a steroid such as Dexamethasone. These products treat or help prevent bacterial infections of minor cuts, scrapes and burns, and bacterial infections of the eye (such as conjunctivitis) or outer ear. Injectable forms are reserved for serious hospital infections.
How It Works
Polymyxin B attaches to the outer wall of certain bacteria, mainly Gram-negative types such as Pseudomonas and E. coli, and damages it so that the bacteria leak and die. Combining it with other antibiotics covers a wider range of germs. When a steroid is included, it also reduces redness, swelling and itching.
Dosage and Administration
Skin ointment or cream: clean the area and apply a small amount 1 to 3 times a day; it may be covered with a light dressing. Eye drops or eye ointment and ear drops: use as prescribed, usually several times a day for about 7 days. Wash your hands before and after use and do not let the tip touch the eye, ear or skin. Injections are given by a doctor or nurse in hospital. Complete the course and do not use for longer than advised.
Interactions
Interactions are unlikely with skin, eye or ear use. When given by injection, using it with other medicines that harm the kidneys or nerves, such as Gentamicin, Amikacin, Vancomycin or strong diuretics, increases the risk of side effects, and it can increase the effect of muscle relaxants used in anaesthesia.
Contraindications
Do not use if you are allergic to polymyxin or any other ingredient (for example Neomycin). Steroid-containing eye drops must not be used for viral eye infections such as herpes, fungal or tuberculous eye infections. Ear drops should not be used if the eardrum is perforated unless a doctor advises. Do not apply to large areas of broken skin or deep wounds.
Side Effects
Topical use may cause local itching, burning, redness or rash. Eye products may cause brief stinging or blurred vision. Allergic contact dermatitis, often caused by neomycin in combination products, can occur. Long use may lead to infection with resistant germs or fungi. With injections, kidney damage, numbness, tingling and muscle weakness can occur.
Get urgent medical help if you have signs of a serious allergic reaction (swelling of the face, lips or throat, difficulty breathing, widespread rash), eye pain or worsening vision, hearing loss or ringing in the ears, or if the infection spreads or does not improve.
Pregnancy and Lactation
Small amounts used on the skin, eye or ear are unlikely to harm the baby, but use only on a doctor’s advice during pregnancy and breastfeeding. Injectable polymyxin is used in pregnancy only when clearly needed.
Precautions and Warnings
Do not use for longer than recommended. Remove contact lenses before using eye products. If a steroid is included, long use in the eye can raise eye pressure or cause cataracts, so regular eye checks are needed. Do not share products with others to avoid spreading infection.
Overdose
Overdose is unlikely with topical use. If a product is swallowed, seek medical advice. Injection overdose can cause kidney failure and breathing difficulty from muscle weakness and needs urgent hospital care.
Therapeutic Class
Polypeptide antibiotic (polymyxin), topical or ophthalmic anti-infective.
Storage
Store below 30°C, away from light and out of the reach of children. Keep the container closed and discard eye and ear drops 4 weeks after opening, or as stated on the pack. Injections are stored as directed on the pack.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.