Microbiology: Mupirocin is an antibacterial agent produced by fermentation using the organism Pseudomonas fluorescens. Its spectrum of activity includes gram-positive bacteria. It is also active, in vitro only, against certain gram-negative bacteria. Mupirocin inhibits bacterial protein synthesis by reversibly and specifically binding to bacterial isoleucyl transfer-RNA synthetase. Due to this unique mode of action, mupirocin does not demonstrate cross-resistance with other classes of antimicrobial agents.

When mupirocin resistance occurs, it results from the production of a modified isoleucyl-tRNA synthetase or the acquisition, by genetic transfer, of a plasmid mediating a new isoleucyl-tRNA synthetase. High-level plasmid-mediated resistance (MIC > 500 mcg/mL) has been reported in increasing numbers of isolates of Staphylococcus aureus and with higher frequency in coagulase-negative staphylococci. Methicillin resistance and mupirocin resistance commonly occur together in Staphylococcus aureus and coagulase negative staphylococci.

Mupirocin is bactericidal at concentrations achieved by topical administration. However, the minimum bactericidal concentration (MBC) against relevant pathogens is generally eight-fold to thirty-fold higher than the minimum inhibitory concentration (MIC). In addition, mupirocin is highly protein bound (>97%), and the effect of wound secretions on the MICs of mupirocin has not been determined.

Mupirocin has been shown to be active against susceptible strains of Staphylococcus aureus and Streptococcus pyogenes, both in vitro and in clinical studies. (See INDICATIONS AND USAGE.)

Information for Patients: Use this medication only as directed by your healthcare provider. It is for external use only. Avoid contact with the eyes. The medication should be stopped and your healthcare practitioner contacted if irritation, severe itching or rash occurs. If impetigo has not improved in 3 to 5 days, contact your healthcare practitioner.

Drug Interactions: The effect of the concurrent application of Centany (mupirocin ointment),2% and other drug products is unknown.

Carcinogenesis, Mutagenesis, Impairment of Fertility: Long-term studies in animals to evaluate carcinogenic potential of mupirocin have not been conducted.

Results of the following studies performed with mupirocin calcium or mupirocin sodium in vitro and in vivo did not indicate a potential for genotoxicity: rat primary hepatocyte unscheduled DNA synthesis, sediment analysis for DNA strand breaks, Salmonella reversion test (Ames), Escherichia coli mutation assay, metaphase analysis of human lymphocytes, mouse lymphoma assay, and bone marrow micronuclei assay in mice.

Reproduction studies were performed in male and female rats with mupirocin administered subcutaneously at doses up to 14 times the human topical dose (approximately 60 mg mupirocin/ day) on a mg/m2 basis and revealed neither evidence of impaired fertility nor impaired reproductive performance attributable to mupirocin.

Pregnancy

Nursing Mothers: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Centany (mupirocin ointment),2% is administered to a nursing woman.

Pediatric Use: The safety and effectiveness of Centany (mupirocin ointment),2% have been established in the age range of 2 months to 16 years. Use of Centany (mupirocin ointment),2% in these age groups is supported by evidence from adequate and well-controlled studies of Centany (mupirocin ointment),2% in impetigo in pediatric patients studied as a part of the pivotal clinical trials. (See CLINICAL STUDIES.)

Pediatrics

There were 413 pediatric patients aged 2 months to 15 years in the clinical study described above. Clinical efficacy rates at follow-up in the evaluable populations were 93% for Centany (mupirocin ointment), 2% (n=199) and 95% for Bactroban® Ointment (mupirocin ointment, 2%) (n=214).