How It Works
Vancomycin is a naturally produced antibiotic made by a specific strain of bacteria (genus Actinonmycetes). It acts primarily by attacking the covering (or cell wall) of certain types of bacteria. These bacteria are usually referred to as “gram-positive” bacteria because their cell walls stain purple or violet during the Gram stain process, which is done to make bacteria visible under a microscope.
- Common gram-positive bacteria include: Staphylococcus, Streptococcus, Enterococcus, Clostridium, Listeria, and Bacillus.
Indications for Vancomycin
Vancomycin is usually reserved for the treatment of serious or severe infections caused by susceptible strains of methicillin-resistant staphylococci (MRSA or coagulase-negative Staphlococcus). It is also used in patients with a penicillin allergy or in infections where the bacteria are highly resistant to other standard antibiotics.
- Vancomycin use has become more restricted because of an increasing emergence of resistant strains of gram-positive bacteria, especially enterococci.
How It Is Administered
Vancomycin is usually administered as an intravenous infusion. This is because it is not well absorbed from the gastrointestinal tract and can cause tissue breakdown (necrosis) when given under the skin (subcutaneous) or in the muscle (intramuscular).
- Oral vancomycin is given for certain infections limited to the inside of the gastrointestinal tract, such as a colon infection (colitis) involving the Clostridium difficile bacteria.
How It Is Removed From the Body
Vancomycin is mainly eliminated from the body by the kidneys. With normal kidney function, half of it is gone in four to six hours. With impaired kidney function, vancomycin is removed less efficiently and lasts a lot longer.
- For someone on dialysis, a single dose of vancomycin can last up to a week.
Dosing Vancomycin
The blood level of vancomycin after a single dose is relatively unpredictable, especially when there is moderate kidney dysfunction. As a result, a number of different dosing methods have been devised. The most common approach involves an initial weight-based dose and then measuring the peak and trough blood levels. The dose and frequency of subsequent infections are then adjusted based on the blood levels.
- The peak level is usually drawn within 2 hours of getting the drug. A peak level of less than 40 ug/mL is generally considered acceptable.
- The trough level is usually drawn immediately before the next dose. A trough level of 10-20 ug/mL is generally considered acceptable.
Side Effects of Vancomycin
Vancomycin is a relativly safe drug. An important side effect to on the look out for is something called the "red man syndrome." It is a histamine-related flushing of the face, neck and trunk. It typically occurs when vancomycin is given intravenously too rapidly. Very rarely, rapid administration can cause low blood pressure and cardiac arrest (anaphylaxis). To help avoid a histamine reaction, vancomycin is usually given at a relatively slow rate (no faster than 1 gram per hour).
- Kidney and eye toxicity have been associated with very high blood levels. However, it may have also occurred because of other "toxic" drugs being given at the same time (such as aminoglycoside antibiotics).
- Oral vancomycin can occasionally cause upset stomach.
Sources:
Lentino, Joseph and Leehey, David. “Infections.” Handbook of Dialysis 3rd Edition. Eds. Daugirdas, Blake & Ing. Philadelphia: Lippincott Williams & Wilkins, 2001. 495-521.