Polymyxin antibiotics contain the active pharmaceutical ingredients (API) colistin sulfate or colistimethate sodium.
These drugs have been available since the 1960s, however, polymyxins are neurotoxic and nephrotoxic and previously their use was limited to serious infections for which no other treatments were available.
While this still holds, the rise of superbugs has changed the dynamic according to the EMA, which said greater incidence of bacterial resistance "has led to a resurgence in recent years in the use of polymyxins in patients with few other options.”
The EMA gave colistimethate sodium - used to treat Pseudomonas aeruginosa infection in cystic fibrosis sufferers - as an example, explaining that limited use means the drug "has retained activity against a number of bacteria which have become resistant to commonly used antibiotics.”
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The agency’s Committee for Medicinal Products for Human Use (CHMP) published its review of polymyxins last week, providing updated advice on when such products should be used.
The CHMP said infusions of colistimethate sodium should be used for serious infections in patients whose treatment options are limited and, ideally, given in combination with another antibiotic.
The Committee also detailed how dosages should be expressed, set out the safe levels for children and patients with kidney problems and gave advice on use of nebulisers to deliver colistimethate sodium.
The EMA added that: “The CHMP opinion will now be forwarded to the European Commission, which will issue a final decision in due course.”
API suppliers
Colistin, also known as polymyxin E, is produced naturally by certain strains of Bacillus bacteria to prevent other organisms colonising neighbouring locations.
Two forms of the compound are available commercially, colistin sulfate and colistimethate sodium, with the former being used to treat internal infections.
Peakdale Pharmaceutical, a subsidiary of King Pharmaceuticals, was previously a key colistin supplier. However, a spokeswoman for King owner Pfizer told in-pharmatechnologist.com the firm no longer makes the API and declined to comment on the EMA review.