"Scientists at the National Institutes of Health report they have discovered in mouse studies that a small molecule released in the spinal cord triggers a process that is later experienced in the brain as the sensation of itch.
Systemic absorption of mupirocin through intact human skin is minimal. The systemic absorption of mupirocin was studied following application of BACTROBAN Cream 3 times daily for 5 days to various skin lesions ( > 10 cm in length or 100 cm² in area) in 16 adults (aged 29 to 60 years) and 10 children (aged 3 to 12 years). Some systemic absorption was observed as evidenced by the detection of the metabolite, monic acid, in urine. Data from this trial indicated more frequent occurrence of percutaneous absorption in children (90% of subjects) compared with adults (44% of subjects); however, the observed urinary concentrations in children (0.07 to 1.3 mcg/mL [1 pediatric subject had no detectable level]) are within the observed range (0.08 to 10.03 mcg/mL [9 adults had no detectable level]) in the adult population. In general, the degree of percutaneous absorption following multiple dosing appears to be minimal in adults and children. Any mupirocin reaching the systemic circulation is rapidly metabolized, predominantly to inactive monic acid, which is eliminated by renal excretion.
Mupirocin is an antibacterial agent produced by fermentation using the organism Pseudomonas fluorescens. Mupirocin inhibits bacterial protein synthesis by reversibly 2 and specifically binding to bacterial isoleucyl transfer-RNA (tRNA) 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 of, by genetic transfer, a plasmid mediating a new isoleucyl-tRNA synthetase. High-level plasmid-mediated resistance (MIC > 512 mcg/mL) has been reported in increasing numbers of isolates of Staphylococcus aureus and with higher frequency in coagulase-negative staphylococci. Mupirocin resistance occurs with greater frequency in methicillin-resistant than methicillin-susceptible staphylococci. Because of the occurrence of mupirocin resistance in methicillin-resistant Staphylococcus aureus (MRSA), it is appropriate to test MRSA populations for mupirocin susceptibility prior to the use of mupirocin using a standardized method.1,2,3
Mupirocin is bactericidal at concentrations achieved by topical application. 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 S. aureus and Streptococcus pyogenes, both in vitro and in clinical trials (see INDICATIONS AND USAGE). The following in vitro data are available, but their clinical significance is unknown. Mupirocin is active against most isolates of Staphylococcus epidermidis.
The efficacy of topical BACTROBAN Cream for the treatment of secondarily infected traumatic skin lesions (e.g., lacerations, sutured wounds, and abrasions not more than 10 cm in length or 100 cm² in total area) was compared with that of oral cephalexin in 2 randomized, double-blind, double-dummy clinical trials. Clinical efficacy rates at follow-up in the per protocol populations (adults and pediatric subjects included) were 96.1% for BACTROBAN Cream (n = 231) and 93.1% for oral cephalexin (n = 219). Pathogen eradication rates at follow-up in the per-protocol populations were 100% for both BACTROBAN Cream and oral cephalexin.
There were 93 pediatric subjects aged 2 weeks to 16 years enrolled per protocol in the secondarily infected skin lesion trials, although only 3 were less than 2 years of age in the population treated with BACTROBAN Cream. Subjects were randomized to either 10 days of topical BACTROBAN Cream 3 times daily or 10 days of oral cephalexin (250 mg 4 times daily for subjects > 40 kg or 25 mg/kg/day oral suspension in 4 divided doses for subjects ≤ 40 kg). Clinical efficacy at follow-up (7 to 12 days post-therapy) in the per-protocol populations was 97.7% (43/44) for BACTROBAN Cream and 93.9% (46/49) for cephalexin. Only 1 adverse event (headache) was thought to be possibly or probably related to drug therapy with BACTROBAN Cream in the intent-to-treat pediatric population of 70 children (1.4%).
1. Clinical and Laboratory Standards Institute (CLSI). Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically; Approved Standard – Tenth Edition. CLSI document M07-A10 , Clinical and Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne, Pennsylvania 19087, USA.
2. Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Antimicrobial Disk Diffusion Susceptibility Tests; Approved Standard – Twelfth Edition. CLSI document M02-A12 , Clinical and Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne, Pennsylvania 19087, USA.
3. Finlay JE, Miller LA, Poupard JA. Interpretive criteria for testing susceptibility of staphylococci to mupirocin. Antimicrob Agents Chemother 1997;41(5):1137-1139.
Last reviewed on RxList: 6/1/2015
This monograph has been modified to include the generic and brand name in many instances.
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