Vancomycin, Serum, Peak

Serum or plasma

1 mL

0.3 mL

Red-top tube, lavender-top (K2- or K3- EDTA) tube, or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.

Use of intravenous vancomycin should be restricted to serious infections caused by susceptible staphylococci or other gram-positive bacteria when other antibiotics are ineffective or not tolerated.

Vancomycin is the drug of choice for serious infections caused by methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci (including S epidermidis). These infections include septicemia, endocarditis, osteomyelitis, pneumonia, lung abscesses, soft tissue infections, wound infections, and meningitis. Lumbar intrathecal or intraventricular administration may be required to treat meningitis.

Methicillin-resistant Staphylococcus epidermidis (and other coagulase-negative staphylococci) has become an important cause of infections associated with indwelling devices, including prosthetic heart valves, prosthetic hips, cerebrospinal fluid shunts, and intravenous (eg, Hickman) catheters. Vancomycin is the drug of choice for treatment of these infections. For prosthetic valve endocarditis caused by methicillin-resistant S epidermidis, intravenous vancomycin in combination with rifampin and gentamicin for two weeks, followed by vancomycin plus rifampin for an additional four weeks, has been recommended. Surgical intervention is frequently required.

Vancomycin is recommended for serious staphylococcal infections in patients who cannot receive (eg, due to hypersensitivity) or have failed to respond to penicillins and cephalosporins.

The combination of vancomycin with gentamicin or streptomycin (for susceptible strains) is the regimen of choice for enterococcal endocarditis in penicillin-allergic patients. Although vancomycin can be used to treat endocarditis caused by viridans streptococci in penicillin-allergic patients, first generation cephalosporins (eg, cefazolin, cephalothin, cephapirin) usually are preferred (unless there also is cephalosporin hypersensitivity).

When given intravenously, vancomycin is useful for prophylaxis of infective endocarditis in high-risk patients who are allergic to penicillin and who are undergoing dental or certain other surgical procedures.

Vancomycin is an alternative to first generation cephalosporins or antistaphylococcal penicillins for prophylaxis during certain surgical procedures (eg, cardiac valve replacement, total hip replacement) in patients allergic to penicillins and cephalosporins.

Vancomycin is the drug of choice for the uncommon pneumococcal infections that are resistant to penicillin G and for serious infections (eg, prosthetic valve endocarditis) caused by the penicillin-resistant JK strains of corynebacteria. It may be effective for Flavobacterium meningosepticum meningitis that is resistant to other antimicrobial agents.

When administered intravenously or intraperitoneally, this drug is useful in the management of peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD). Gram-positive bacteria, particularly staphylococci, are the most common causative organisms of these infections.

Vancomycin is poorly absorbed from the gastrointestinal tract. Oral vancomycin is a drug of choice for antibiotic-associated pseudomembranous colitis (AAPMC) caused by Clostridium difficile, especially in seriously ill patients; however, oral metronidazole appears to be an effective and considerably less expensive alternative for mild-to-moderate disease and is frequently preferred in these patients.

Immunoassay

• Therapeutic: 25.0−40.0 μg/mL

• Detection limit: 2.0 μg/mL; <2.0 μg/mL indicates none detected

Note: Peak levels drawn at 30 minutes are more variable and very dependent on consistent timing of collections. Differences of as little as 15 minutes in sampling time can result in a 10−15 μg/mL difference in measured vancomycin concentrations. It is important that consistency be maintained in the dosage interval and infusion period throughout the course of therapy for comparison of vancomycin concentrations to be valid. Peak levels collected at two hours are less variable.

Following slow intravenous infusion of 1 g, peak serum concentrations of 25.0−40.0 μg/mL and trough levels of 10.0−15.0 μg/mL are observed. Approximately 55% of circulating vancomycin is bound to plasma proteins. The steady-state volumes of distribution in adult and pediatric subjects range from 0.39−0.92 L/kg and 0.45−0.97 L/kg, respectively. Adequate concentrations of drug are attained in pleural, ascitic, pericardial, and synovial fluids. Low levels are found in bile; however, in patients with normal renal function, high concentrations are attained in urine. Vancomycin does not penetrate the uninflamed meninges, but therapeutic levels may be attained in cerebrospinal fluid in the presence of meningitis. Lumbar intrathecal or intraventricular administration may be necessary in some patients. Information on concentrations in human tissues is very limited. Potentially therapeutic concentrations of vancomycin have been observed in peritoneal dialysis fluid after intravenous administration in patients undergoing continuous ambulatory peritoneal dialysis.

Vancomycin is eliminated by the kidneys, primarily by glomerular filtration; 80% to 90% of a dose appears in the urine of healthy subjects as unchanged drug within 24 hours. The usual elimination half-life in adults with normal renal function ranges from three to nine hours (mean, six hours). In one study, longer elimination half-lives were reported for men older than 60 years compared to men between 20 and 26 years (mean half-lives, 12.1 and 7.2 hours, respectively). Elimination half-lives are 5.9 to 9.8 hours in newborns, 4.1 hours in older infants, and 2.2 to 4 hours in children. In anuric patients, the half-life may be prolonged to eight or nine days. Dosage reductions are necessary in patients with renal insufficiency. Although it has been reported that elimination is prolonged in patients with impaired hepatic function, the consensus is that nonrenal elimination is minor and dosage reductions are unnecessary.