Pharmacokinetics

Following single or repeated intranasal applications of 0.2 gram of BACTROBAN NASAL 3 times daily for 3 days to 5 healthy adult male subjects, no evidence of systemic absorption of mupirocin was demonstrated. The dosage regimen used in this study was for pharmacokinetic characterization only. (See DOSAGE AND ADMINISTRATION for proper clinical dosing information.)

In this study, the concentrations of mupirocin in urine and of monic acid in urine and serum were below the limit of determination of the assay for up to 72 hours after the applications. The lowest levels of determination of the assay used were 50 ng/mL of mupirocin in urine, 75 ng/mL of monic acid in urine, and 10 ng/mL of monic acid in serum. Based on the detectable limit of the urine assay for monic acid, one can extrapolate that a mean of 3.3% (range: 1.2 to 5.1%) of the applied dose could be systemically absorbed from the nasal mucosa of adults.

Data from a report of a pharmacokinetic study in neonates and premature infants indicate that, unlike in adults, significant systemic absorption occurred following intranasal administration of BACTROBAN NASAL in this population. At this time, the pharmacokinetic properties of mupirocin following intranasal application of BACTROBAN NASAL have not been adequately characterized in neonates or other children less than 12 years of age, and in addition, the safety of the product in children less than 12 years of age has not been established.

The effect of the concurrent application of intranasal mupirocin calcium ointment, 2% with other intranasal products has not been studied. (See PRECAUTIONS, Drug Interactions.)

Following intravenous or oral administration, mupirocin is rapidly metabolized. The principal metabolite, monic acid, demonstrates no antibacterial activity. In a study conducted in 7 healthy adult male subjects, the elimination half-life after intravenous administration of mupirocin was 20 to 40 minutes for mupirocin and 30 to 80 minutes for monic acid. Monic acid is predominantly eliminated by renal excretion. The pharmacokinetics of mupirocin has not been studied in individuals with renal insufficiency.

Microbiology

Mupirocin is an antibacterial agent produced by fermentation using the organism Pseudomonas fluorescens. Mupirocin inhibits bacterial protein synthesis by reversibly and specifically binding to bacterial isoleucyl transfer-RNA synthetase. Due to this mode of action, mupirocin demonstrates no in vitro cross-resistance with other classes of antimicrobial agents.

When mupirocin resistance does occur, it appears to result from the production of a modified isoleucyl-tRNA synthetase. High-level plasmid-mediated resistance (MIC >1,024 mcg/mL) has been reported in some strains of Staphylococcus aureus and coagulase-negative staphylococci.

Mupirocin is bactericidal at concentrations achieved topically by intranasal administration. However, the minimum bactericidal concentration (MBC) against relevant intranasal pathogens is generally 8-fold to 30-fold higher than the minimum inhibitory concentration (MIC). In addition, mupirocin is highly protein bound (>97%), and the effect of nasal secretions on the MICs of intranasally applied mupirocin has not been determined.

Mupirocin has been shown to be active against most strains of methicillin-resistant S. aureus, both in vitro and in clinical studies of the eradication of nasal colonization. BACTROBAN NASAL only has established clinical utility in nasal eradication as part of a comprehensive program to curtail institutional outbreaks of infections with methicillin-resistant S. aureus. (See INDICATIONS AND USAGE.)

The following in vitro data are available, but their clinical significance is unknown. Mupirocin exhibits in vitro MICs of 1 mcg/mL or less against most (>90%) strains of methicillin-susceptible S. aureus; however, the safety and effectiveness of mupirocin calcium in eradicating nasal colonization of and preventing subsequent infections due to methicillin-susceptible S. aureus have not been established.

General

As with other antibacterial products, prolonged use may result in overgrowth of nonsusceptible microorganisms, including fungi. (See DOSAGE AND ADMINISTRATION.)

Information for Patients

Patients should be given the following instructions:

• Apply approximately one-half of the ointment from the single-use tube directly into 1 nostril and the other half into the other nostril;
• Avoid contact of the medication with the eyes;
• Discard the tube after using, do not re-use;
• Press the sides of the nose together and gently massage after application to spread the ointment throughout the inside of the nostrils; and
• Discontinue usage of the medication and call your healthcare practitioner if sensitization or severe local irritation occurs.

Drug Interactions

The effect of the concurrent application of intranasal mupirocin calcium and other intranasal products has not been studied. Until further information is known, mupirocin calcium ointment, 2% should not be applied concurrently with any other intranasal products.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Long-term studies in animals to evaluate carcinogenic potential of mupirocin calcium 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 mutagenicity: 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 rats with mupirocin administered subcutaneously at doses up to 40 times the human intranasal dose (approximately 20 mg mupirocin per day) on a mg/m2 basis and revealed no evidence of impaired fertility from mupirocin sodium.

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 BACTROBAN NASAL is administered to a nursing woman.

Pediatric Use

Safety in children under the age of 12 years has not been established. (See CLINICAL PHARMACOLOGY.)

Clinical Trials

In clinical trials, 210 domestic and 2,130 foreign adult subjects/patients received BACTROBAN NASAL ointment. Less than 1% of domestic or foreign subjects and patients in clinical trials were withdrawn due to adverse events.

The most frequently reported adverse events in foreign clinical trials were as follows: Rhinitis (1.0%), taste perversion (0.8%), pharyngitis (0.5%).

In domestic clinical trials, 17% (36/210) of adults treated with BACTROBAN NASAL ointment reported adverse events thought to be at least possibly drug-related. The incidence of adverse events that were reported in at least 1% of adults enrolled in domestic clinical trials were as follows:

The following events thought possibly drug-related were reported in less than 1% of adults enrolled in domestic clinical trials: Blepharitis, diarrhea, dry mouth, ear pain, epistaxis, nausea, and rash.

All adequate and well-controlled clinical trials have been performed using BACTROBAN NASAL ointment, 2% in 1 arm and the vehicle ointment in the other arm of the study. No adequate and well-controlled safety data are available from direct, head-to-head comparative studies of this product and other products for this indication.

Additional barcode labeling by:
Physicians Total Care, Inc.
Tulsa, Oklahoma        74146