Colistin sulfate is a medication that has antibiotic properties, and is therefore often used to treat bacterial infections. A form of this compound is naturally produced by some bacteria in nature as a defense mechanism against other species. Its discovery led to colistin becoming adapted for medicinal use. Only certain types of bacteria are affected by this drug, which is why it is generally taken for intestinal infections, and sometimes for infections on the surface of the skin. Usually it is only used in last-resort situations, against germs that have proven to be resistant against other antibiotics.
Bacterial cell membranes have ions that help keep these barriers intact. Colistin sulfate can replace these ions, opening up the membrane and dissolving it. Liquids can then enter the affected bacterium, which destroy it. Variations in the ionic region of this medication have led to two distinguishable forms of this drug, colistin sulfate and colistimethate sodium. Each of these compounds can be optimally effective against different species of germs.
Like other medications, the right colistin sulfate dose must be used to provide benefits while minimizing side effects. Often, a colistin dose is used that is equal to 1 and 1.5 mg for every 2.2 pounds (1 kilogram) of body weight. Otherwise healthy children and adults may use this dose every eight hours, but people with kidney damage may only take their doses one to two times a day. Sometimes, dosages are given in a measurement called international units. In this case, one to two million units are usually considered a full dose for treatment.
In most cases, colistin sulfate is used in an injectable form, either through intramuscular (IM) or intravenous (IV) injection. This form of the medication can be combined with other IV solutions like saline, but usually not with other drugs. Topical preparations of this drug have been produced in some areas to treat infections on the skin, however, and these may feature colistin mixed with other drugs, like hydrocortisone.
As mentioned, adverse effects can occur when taking this drug, occasionally at therapeutic levels. Side effects of colistin sulfate can include nausea, tingling or numb sensations in the hands and feet, and breathing problems. High doses of this medication have been linked to nerve and kidney damage. Generally, the risk of this damage is small at lower doses, even when these doses are used for months at a time.