In addition to reports in clinical trials, the following events have been identified during postmarketing use of ALTABAX. Because these events are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
General Disorders and Administration Site Conditions
Application site burning.
Immune System Disorders
Hypersensitivity including angioedema.
Coadministration of oral ketoconazole 200 mg twice daily increased retapamulin geometric mean AUC(0-24) and Cmax by 81% after topical application of retapamulin ointment, 1% on the abraded skin of healthy adult males. Due to low systemic exposure to retapamulin following topical application in adults and pediatric patients aged 2 years and older, dosage adjustments for retapamulin are unnecessary in these patients when coadministered with CYP3A4 inhibitors, such as ketoconazole. Based on in vitro P450 inhibition studies and the low systemic exposure observed following topical application of ALTABAX, retapamulin is unlikely to affect the metabolism of other P450 substrates.
Concomitant administration of retapamulin and CYP3A4 inhibitors, such as ketoconazole, has not been studied in pediatric patients. In pediatric subjects aged 2 to 24 months, systemic exposure of retapamulin was higher compared with subjects aged 2 years and older after topical application [see Pharmacokinetics (12.3)]. Based on the higher exposure of retapamulin, it is not recommended to coadminister ALTABAX with strong CYP3A4 inhibitors in patients younger than 24 months.
The effect of concurrent application of ALTABAX and other topical products to the same area of skin has not been studied.
There are no available data on ALTABAX use in pregnant women to inform any drug associated risk for major birth defects, miscarriage or adverse maternal or fetal outcomes. Retapamulin is negligibly absorbed systemically following topical administration and maternal use is not expected to result in fetal exposure to the retapamulin [see Clinical Pharmacology (12.3)]. Animal reproduction studies were not conducted with ALTABAX. However, in animal studies where retapamulin was administered by oral gavage or intravenous infusion to pregnant rats and rabbits, respectively, during organogenesis, maternal toxicity was seen at doses greater than or equal to 150 mg/kg/day and 7.2 mg/kg/day (8-fold the maximum achievable human exposure based on AUC) for oral and intravenous routes, respectively. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population the background risk of major birth defects in clinically recognized pregnancies is 2% to 4% and of miscarriage is 15% to 20%, respectively.
There are no data available on the presence of retapamulin in human milk, its effects on the breastfed infant or its effects on milk production. However, breastfeeding is not expected to result in exposure of the child to the drug due to the negligible systemic absorption of retapamulin in humans following topical administration of ALTABAX [see Clinical Pharmacology (12.3)].
The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for ALTABAX and any potential adverse effects on the breastfed infant from ALTABAX or from the underlying maternal condition.
The safety and effectiveness of ALTABAX in the treatment of impetigo have been established in pediatric patients aged 9 months to 17 years. Use of ALTABAX in pediatric patients (9 months to 17 years of age) is supported by evidence from adequate and well-controlled trials of ALTABAX in which 588 pediatric subjects received at least one dose of retapamulin ointment, 1% [see Adverse Reactions (6.1), Clinical Studies (14)]. The magnitude of efficacy and the safety profile of ALTABAX in pediatric subjects 9 months and older were similar to those in adults.
The safety and effectiveness of ALTABAX in pediatric patients younger than 9 months have not been established. An open-label clinical trial of topical treatment with ALTABAX (twice daily for 5 days) was conducted in subjects aged 2 to 24 months. Plasma samples were obtained from 79 subjects. In these pediatric subjects, systemic exposure of retapamulin was higher compared with subjects aged 2 to 17 years. Furthermore, a higher proportion of pediatric subjects aged 2 to 9 months had measurable concentrations (greater than 0.5 ng per mL) of retapamulin compared with subjects aged 9 to 24 months [see Pharmacokinetics (12.3)]. The highest levels were seen in subjects aged 2 to 6 months [see Pharmacokinetics (12.3)]. The use of retapamulin is not indicated in pediatric patients younger than 9 months.
Of the total number of subjects in the adequate and well-controlled trials of ALTABAX, 234 subjects were aged 65 years and older, of whom 114 subjects were aged 75 years and older. No overall differences in effectiveness or safety were observed between these subjects and younger adult subjects.
Overdosage with ALTABAX has not been reported. Any signs or symptoms of overdose, either topically or by accidental ingestion, should be treated symptomatically consistent with good clinical practice.
There is no known antidote for overdoses of ALTABAX.
ALTABAX contains retapamulin, a semisynthetic pleuromutilin antibiotic. The chemical name of retapamulin is acetic acid, [[(3-exo)-8-methyl-8-azabicyclo[3.2.1]oct-3-yl]thio]-, (3aS ,4R ,5S ,6S ,8R ,9R ,9aR ,10R)-6-ethenyldecahydro-5-hydroxy-4,6,9,10-tetramethyl-1-oxo-3a,9-propano-3aH -cyclopentacycloocten-8-yl ester. Retapamulin, a white to pale-yellow crystalline solid, has a molecular formula of C30 H47 NO4 S, and a molecular weight of 517.78. The chemical structure is:
Each gram of ointment for dermatological use contains 10 mg of retapamulin in white petrolatum.
ALTABAX is an antibacterial agent [see Clinical Pharmacology (12.4)].
In post-hoc analyses of manually over-read 12-lead ECGs from healthy subjects (N = 103), no significant effects on QT/QTc intervals were observed after topical application of retapamulin ointment on intact and abraded skin. Due to the low systemic exposure to retapamulin with topical application, QT prolongation in patients is unlikely [see Clinical Pharmacology (12.3)].
In a trial of healthy adult subjects, retapamulin ointment, 1% was applied once daily to intact skin (800 cm2 surface area) and to abraded skin (200 cm2 surface area) under occlusion for up to 7 days. Systemic exposure following topical application of retapamulin through intact and abraded skin was low. Three percent of blood samples obtained on Day 1 after topical application to intact skin had measurable retapamulin concentrations (lower limit of quantitation 0.5 ng per mL); thus Cmax values on Day 1 could not be determined. Eighty-two percent of blood samples obtained on Day 7 after topical application to intact skin and 97% and 100% of blood samples obtained after topical application to abraded skin on Days 1 and 7, respectively, had measurable retapamulin concentrations. The median Cmax value in plasma after application to 800 cm2 of intact skin was 3.5 ng per mL on Day 7 (range: 1.2 to 7.8 ng per mL). The median Cmax value in plasma after application to 200 cm2 of abraded skin was 11.7 ng per mL on Day 1 (range: 5.6 to 22.1 ng per mL) and 9.0 ng per mL on Day 7 (range: 6.7 to 12.8 ng per mL).
Plasma samples were obtained from 380 adult subjects and 136 pediatric subjects (aged 2 to 17 years) who were receiving topical treatment with ALTABAX topically twice daily. Eleven percent had measurable retapamulin concentrations (lower limit of quantitation 0.5 ng per mL), of which the median concentration was 0.8 ng per mL. The maximum measured retapamulin concentration in adults was 10.7 ng per mL and in pediatric subjects (aged 2 to 17 years) was 18.5 ng per mL.
A single plasma sample was obtained from 79 pediatric subjects (aged 2 to 24 months) who were receiving topical treatment with ALTABAX twice daily. Forty-six percent had measurable retapamulin concentrations greater than 0.5 ng per mL) compared with 7% in pediatric subjects aged 2 to 17 years. A higher proportion (69%) of pediatric subjects aged 2 to 9 months had measurable concentrations of retapamulin compared with subjects aged 9 to 24 months (32%). Among pediatric subjects aged 2 to 9 months (n = 29), 4 subjects had retapamulin concentrations that were higher (greater than or equal to 26.9 ng per mL) than the maximum concentration observed in pediatric subjects aged 2 to 17 years (18.5 ng per mL). Among pediatric subjects aged 9 to 24 months (n = 50), 1 subject had a retapamulin concentration that was higher (95.1 ng per mL) than the maximum level observed in pediatric subjects aged 2 to 17 years.
Retapamulin is approximately 94% bound to human plasma proteins, and the protein binding is independent of concentration. The apparent volume of distribution of retapamulin has not been determined in humans.
In vitro studies with human hepatocytes showed that the main routes of metabolism were mono-oxygenation and di-oxygenation. In vitro studies with human liver microsomes demonstrated that retapamulin is extensively metabolized to numerous metabolites, of which the predominant routes of metabolism were mono-oxygenation and N-demethylation. The major enzyme responsible for metabolism of retapamulin in human liver microsomes was cytochrome P450 3A4 (CYP3A4).
Retapamulin elimination in humans has not been investigated due to low systemic exposure after topical application.
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