Polymyxin B is a medication given to treat a number of different types of infections caused by bacteria. It works by destroying the integrity of the bacterial cell walls, making them susceptible to external pathogenic agents and rendering them unable to maintain a stable internal environment conducive to survival. Most often polymyxin B is included in an ointment, eye drops, or ear drops as a way to treat bacterial infections affecting these parts of the body. Side effects of the medication most commonly include local irritation and redness of the skin.
The mechanism of action of polymyxin B is to harm the integrity of bacterial cell walls. It is able to do this by interfering with some of the chemical bonds that are important in maintaining the strength of these protective structures. The drug is naturally produced by a bacterial species known as Bacillus polymyxa, which makes the substance as a defense mechanism against other types of bacteria. Types of bacteria known as gram negative bacteria are the most susceptible to being killed by this mechanism of action.
Typically, polymyxin B is not given as a pill or an injection. Instead, it is applied locally to different parts of the body that might be affected by bacterial infections. One popular use of the medication is to include it in an ointment to treat skin infections. Preparations are also available as eye drops to treat eye infections, or as ear drops to treat ear infections. Often the medication is combined with other antibacterial agents in order to best kill a variety of bacteria.
Side effects of polymyxin B are typically minimal, but can include skin reactions such as redness or irritation. Some people might be allergic to the medication, and they can develop more severe side effects including swelling and a rash. Patients who use preparations of polymyxin B for extended periods of time could become susceptible to infection with bacteria that are resistant to the medication, and could have problems with fully eradicating their infections.
In most cases, polymyxin B is well tolerated, and it is even available in ointment form over the counter in the United States. Some people, however, should avoid the use of this medication. The safety of the drug in pregnant and lactating women is not well established. Also, patients with undiagnosed conditions should consult with a doctor or other health care professional prior to using the medication to ensure they are receiving the best possible treatment.