What Factors Affect a Sufficient Vancomycin Dosage?

Vancomycin, a powerful antibiotic medication used to treat a number of different infections, can be difficult to administer correctly. A number of factors affect proper vancomycin dosage, including the patient's weight and how well his or her kidneys work. Often the levels of vancomycin in the patient’s blood are monitored as he or she is being treated with this medication. Although typically vancomycin is given as an intravenous medication, it can also be given as an oral medication.

The most important factor affecting vancomycin dosage is the patient's body weight. In order to calculate how much of this antibiotic a person requires, it is important to know his or her current weight, either in pounds or kilograms. Typically patients are given 66-132 milligrams (mg) per pound (lb) or 30-60 mg per kilogram (kg) per day. Often this total daily requirement is spread over a couple of doses, for example two doses each comprising 33-44 mg per lb (15-20 mg per kg) per day.

A person's dose of vancomycin is also affected by how well his or her kidneys are functioning. The medication is removed from the body by the kidneys, and if these organs are not working well, it tends to build up to high levels in the body. This can be dangerous because vancomycin can cause damage to the body at high doses. Patients with impaired kidney function are therefore generally given a decreased vancomycin dosage, which is adjusted based on their underlying renal function.

Some people have variations in how their body metabolizes and gets rid of vancomycin. For this reason, in hospitals it is a common practice to monitor the level of vancomycin in the patient's blood during the course of treatment. Often, a vancomycin trough level is checked. The concentration of the medication is checked half an hour prior to the administration of the morning dose on the third day of treatment. This value should fall within a certain range in order for the current vancomycin dosage to be considered therapeutic; if it does not, subsequent doses can be increased or decreased as needed.

Although vancomycin is usually given as an intravenous medication, meaning that it is administered as a solution directly into a patient's veins, for select infections it is given as a medication taken by mouth. Infections of the gastrointestinal tract, such as an infection of the colon known as colitis, respond better to vancomycin when it is given orally. Patients taking the medication by mouth take 500-2,000 mg of vancomycin per day, taking a portion of this total daily dose every six hours.