(oritavancin) Injection for Intravenous Administration
ORBACTIV (oritavancin) for injection contains oritavancin diphosphate, a semisynthetic lipoglycopeptide antibacterial drug.
The chemical name for oritavancin is [4"R]-22-O-(3-amino-2,3,6-trideoxy-3-C-methyl-α-L-arabinohexopyranosyl)- N3''-[(4'-chloro[1,1'-biphenyl]-4-yl)methyl] vancomycin phosphate [1:2] [salt]. The empirical formula of oritavancin diphosphate is C86H97N10O26Cl3 •2H3PO4 and the molecular weight is 1989.09. The chemical structure is represented below:
ORBACTIV is supplied as a sterile white to off-white lyophilized powder for intravenous infusion that contains oritavancin diphosphate, mannitol (an inactive ingredient) and phosphoric acid (to adjust pH 3.1 to 4.3). Each 50 ml capacity glass vial contains 449 mg oritavancin diphosphate (equivalent to 405 mg of oritavancin, 5 mg excess is to ensure withdrawal of 400 mg oritavancin), 400 mg oritavancin (free base equivalent).
Each vial is reconstituted with sterile water for injection and further diluted with 5% Dextrose in sterile Water for intravenous infusion. Both the reconstituted solution and the diluted solution for infusion should be clear, colorless to pale yellow solution [see DOSAGE AND ADMINISTRATION].
Acute Bacterial Skin And Skin Structure Infections
ORBACTIV® (oritavancin) for injection is indicated for the treatment of adult patients with acute bacterial skin and skin structure infections (ABSSSI) caused by susceptible isolates of the following Gram-positive microorganisms:
Staphylococcus aureus (including methicillin-susceptible and methicillin–resistant isolates), Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus anginosus group (includes S. anginosus, S. intermedius, and S. constellatus), and Enterococcus faecalis (vancomycin-susceptible isolates only).
To reduce the development of drug-resistant bacteria and maintain the effectiveness of ORBACTIV and other antibacterial drugs, ORBACTIV should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.
DOSAGE AND ADMINISTRATION
The recommended dosing for ORBACTIV is a single 1200 mg dose administered by intravenous infusion over 3 hours in patients 18 years and older.
Preparation Of ORBACTIV For Intravenous Infusion
ORBACTIV is intended for intravenous infusion, only after reconstitution and dilution.
Three ORBACTIV 400 mg vials need to be reconstituted and diluted to prepare a single 1200 mg intravenous dose.
Aseptic technique should be used to reconstitute three ORBACTIV 400 mg vials.
- Add 40 mL of sterile water for injection (WFI) to reconstitute each vial to provide a 10 mg/mL solution per vial.
- For each vial, gently swirl to avoid foaming and ensure that all ORBACTIV powder is completely reconstituted in solution.
- Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Each reconstituted vial should appear to be clear, colorless to pale yellow solution.
Use ONLY 5% dextrose in sterile water (D5W) for dilution. Do NOT use Normal Saline for dilution as it is incompatible with ORBACTIV and may cause precipitation of the drug. Use aseptic technique to:
- Withdraw and discard 120 mL from a 1000 mL intravenous bag of D5W.
- Withdraw 40 mL from each of the three reconstituted vials and add to D5W intravenous bag to bring the bag volume to 1000 mL. This yields a concentration of 1.2 mg/mL.
Discard any unused portion of reconstituted solution.
Since no preservative or bacteriostatic agent is present in this product, aseptic technique must be used in preparing the final intravenous solution.
Diluted intravenous solution in an infusion bag should be used within 6 hours when stored at room temperature, or used within 12 hours when refrigerated at 2 to 8°C (36 to 46°F). The combined storage time (reconstituted solution in the vial and diluted solution in the bag) and 3 hour infusion time should not exceed 6 hours at room temperature or 12 hours if refrigerated.
ORBACTIV is administered intravenously. ORBACTIV should only be diluted in D5W. Do NOT use normal saline for dilution as it is incompatible with ORBACTIV and may cause precipitation of the drug. Therefore other intravenous substances, additives or other medications mixed in normal saline should not be added to ORBACTIV single-dose vials or infused simultaneously through the same IV line or through a common intravenous port. In addition, drugs formulated at a basic or neutral pH may be incompatible with ORBACTIV. ORBACTIV should not be administered simultaneously with commonly used intravenous drugs through a common intravenous port. If the same intravenous line is used for sequential infusion of additional medications, the line should be flushed before and after infusion of ORBACTIV with D5W.
Dosage Forms And Strengths
ORBACTIV is supplied as sterile, white to off-white lyophilized powder equivalent to 400 mg of oritavancin in a single-dose 50 mL clear glass vial.
Storage And Handling
ORBACTIV is supplied as single-dose 50 mL capacity glass vials containing sterile lyophilized powder equivalent to 400 mg of oritavancin (NDC 70842-140-01). Three vials are packaged in a carton to supply a single 1200 mg dose treatment (NDC 70842-140-03).
ORBACTIV vials should be stored at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F) [see USP, Controlled Room Temperature (CRT)].
Marketed By: Melinta Therapeutics, Inc. Lincolnshire, IL 60069 USA. Revised: Dec 2019
The following adverse reactions are also discussed in the Warnings and Precautions section of labeling:
Hypersensitivity Reactions [see WARNINGS AND PRECAUTIONS]
Infusion Related Reactions [see WARNINGS AND PRECAUTIONS]
Clostridium difficile-associated Diarrhea [see WARNINGS AND PRECAUTIONS]
Osteomyelitis [see WARNINGS AND PRECAUTIONS]
Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of ORBACTIV cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
ORBACTIV has been evaluated in two, double-blind, controlled ABSSSI clinical trials, which included 976 adult patients treated with a single 1200 mg intravenous dose of ORBACTIV and 983 patients treated with intravenous vancomycin for 7 to 10 days. The median age of patients treated with ORBACTIV was 45.6 years, ranging between 18 and 89 years of age with 8.8% ≥65 years of age. Patients treated with ORBACTIV were predominantly male (65.4%), 64.4% were Caucasian, 5.8% were African American, and 28.1% were Asian. Safety was evaluated for up to 60 days after dosing.
In the pooled ABSSSI clinical trials, serious adverse reactions were reported in 57/976 (5.8%) patients treated with ORBACTIV and 58/983 (5.9%) treated with vancomycin. The most commonly reported serious adverse reaction was cellulitis in both treatment groups: 11/976 (1.1%) in ORBACTIV and 12/983 (1.2%) in the vancomycin arms, respectively.
The most commonly reported adverse reactions (≥3%) in patients receiving a single 1200 mg dose of ORBACTIV in the pooled ABSSSI clinical trials were: headache, nausea, vomiting, limb and subcutaneous abscesses, and diarrhea.
In the pooled ABSSSI clinical trials, ORBACTIV was discontinued due to adverse reactions in 36/976 (3.7%) of patients; the most common reported reactions leading to discontinuation were cellulitis (4/976, 0.4%) and osteomyelitis (3/976, 0.3%).
Table 1 provides selected adverse reactions occurring in ≥1.5% of patients receiving ORBACTIV in the pooled ABSSSI clinical trials. There were 540 (55.3%) patients in the ORBACTIV arm and 559 (56.9%) patients in the vancomycin arm, who reported ≥1 adverse reaction.
Table 1: Incidence of Selected Adverse Reactions Occurring in ≥1.5% of Patients Receiving ORBACTIV in the Pooled ABSSSI Clinical Trials
|Diarrhea||36 (3.7)||32 (3.4)|
|Nausea||97 (9.9)||103 (10.5)|
|Vomiting||45 (4.6)||46 (4.7)|
|Nervous system disorders|
|Dizziness||26 (2.7)||26 (2.6)|
|Headache||69 (7.1)||66 (6.7)|
|General disorders and administration|
|Infusion site phlebitis||24 (2.5)||15 (1.5)|
|Infusion site reaction||19 (1.9)||34 (3.5)|
|Infections and infestations|
|Abscess (limb and subcutaneous)||37 (3.8)||23 (2.3)|
|Alanine aminotransferase increased||27 (2.8)||15 (1.5)|
|Aspartate aminotransferase increased||18 (1.8)||15 (1.5)|
|Tachycardia||24 (2.5)||11 (1.1)|
The following selected adverse reactions were reported in ORBACTIV-treated patients at a rate of less than 1.5%:
Immune system disorders: hypersensitivity
Infections and infestations: osteomyelitis
Investigations: total bilirubin increased, hyperuricemia
Metabolism and nutrition disorders: hypoglycemia
Musculoskeletal and connective tissue disorders: tenosynovitis, myalgia
Respiratory, thoracic and mediastinal disorders: bronchospasm, wheezing
Effect Of ORBACTIV On CYP Substrates
A screening drug-drug interaction study indicated that ORBACTIV is a nonspecific, weak inhibitor (CYP2C9 and CYP2C19) or inducer (CYP3A4 and CYP2D6) of several CYP isoforms [see CLINICAL PHARMACOLOGY]. A drug-drug interaction study that assessed the interaction potential of a single 1200 mg dose of ORBACTIV on the pharmacokinetics of S-warfarin (CYP2C9 probe substrate) showed no effect of ORBACTIV on S-warfarin Cmax or AUC.
Avoid administering ORBACTIV concomitantly with drugs that are predominantly metabolized by one of the affected CYP450 enzymes, as co-administration may increase or decrease concentrations of those drugs. Patients should be closely monitored for signs of toxicity or lack of efficacy if they have been given ORBACTIV while on a potentially affected compound (e.g. patients should be monitored for bleeding if concomitantly receiving ORBACTIV and warfarin).
Drug-Laboratory Test Interactions
ORBACTIV may artificially prolong certain laboratory coagulation tests (see Table 2) by binding to and preventing the action of the phospholipid reagents which activate coagulation in commonly used laboratory coagulation tests [see CONTRAINDICATIONS and WARNINGS AND PRECAUTIONS]. For patients who require monitoring of anticoagulation effect within the indicated time after ORBACTIV dosing, a non-phospholipid dependent coagulation test such as a Factor Xa (chromogenic) assay or an alternative anticoagulant not requiring aPTT monitoring may be considered.
Table 2: Coagulation Tests Affected and Unaffected by ORBACTIV
|Elevated by ORBACTIV||Unaffected by ORBACTIV|
|Prothrombin time (PT) up to 12 hours||Chromogenic Factor Xa Assay|
|International normalized ratio (INR) up to 12 hours||Thrombin Time (TT)|
|Activated partial thromboplastin time (aPTT) up to 120 hours|
|Activated clotting time (ACT) up to 24 hours|
|Silica clot time (SCT) up to 18 hours|
|Dilute Russell’s viper venom time (DRVVT) up to 72 hours|
|D-dimer up to 72 hours|
Included as part of the "PRECAUTIONS" Section
Coagulation Test Interference
ORBACTIV has been shown to artificially prolong aPTT for up to 120 hours, PT and INR for up to 12 hours, and activated clotting time (ACT) for up to 24 hours following administration of a single 1200 mg dose by binding to and preventing action of the phospholipid reagents commonly used in laboratory coagulation tests. ORBACTIV has also been shown to elevate D-dimer concentrations up to 72 hours after ORBACTIV administration.
For patients who require aPTT monitoring within 120 hours of ORBACTIV dosing, a non-phospholipid dependent coagulation test such as a Factor Xa (chromogenic) assay or an alternative anticoagulant not requiring aPTT monitoring may be considered [see CONTRAINDICATIONS and DRUG INTERACTIONS].
ORBACTIV has no effect on the coagulation system in vivo.
Serious hypersensitivity reactions, including anaphylaxis, have been reported with the use of ORBACTIV. If an acute hypersensitivity reaction occurs during ORBACTIV infusion, discontinue ORBACTIV immediately and institute appropriate supportive care. Before using ORBACTIV, inquire carefully about previous hypersensitivity reactions to glycopeptides. Due to the possibility of cross-sensitivity, carefully monitor for signs of hypersensitivity during ORBACTIV infusion in patients with a history of glycopeptide allergy. In the Phase 3 ABSSSI clinical trials, the median onset of hypersensitivity reactions in ORBACTIV-treated patients was 1.2 days and the median duration of these reactions was 2.4 days [see ADVERSE REACTIONS].
Infusion Related Reactions
ORBACTIV is administered as a single dose by intravenous infusion, using a total infusion time of 3 hours to minimize the risk of infusion-related reactions. Infusion related reactions have been reported with the glycopeptide class of antimicrobial agents, including ORBACTIV, that resemble “Red-man Syndrome”, including flushing of the upper body, urticaria, pruritus and/or rash [see ADVERSE REACTIONS]. Infusion reactions characterized by chest pain, back pain, chills and tremor have been observed with the use of ORBACTIV, including after the administration of more than one dose of ORBACTIV during a single course of therapy. Stopping or slowing the infusion may result in cessation of these reactions. The safety and effectiveness of more than one dose of ORBACTIV during a single course of therapy have not been established [see DOSAGE AND ADMINISTRATION].
Clostridium Difficile-Associated Diarrhea
Clostridium difficile-associated diarrhea (CDAD) has been reported for nearly all systemic antibacterial drugs, including ORBACTIV, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon and may permit overgrowth of C. difficile.
C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin-producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antibacterial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibacterial use. Careful medical history is necessary because CDAD has been reported to occur more than 2 months after the administration of antibacterial agents.
If CDAD is suspected or confirmed, antibacterial use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibacterial treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.
Potential Risk Of Bleeding With Concomitant Use Of Warfarin
ORBACTIV has been shown to artificially prolong prothrombin time (PT) and international normalized ratio (INR) for up to 12 hours, making the monitoring of the anticoagulation effect of warfarin unreliable up to 12 hours after an ORBACTIV dose [see Coagulation Test Interference].
Patients should be monitored for bleeding if concomitantly receiving ORBACTIV and warfarin [see DRUG INTERACTIONS].
In Phase 3 ABSSSI clinical trials, more cases of osteomyelitis were reported in the ORBACTIV treated arm than in the vancomycin-treated arm. Monitor patients for signs and symptoms of osteomyelitis. If osteomyelitis is suspected or diagnosed, institute appropriate alternate antibacterial therapy [see ADVERSE REACTIONS].
Development Of Drug Resistant Bacteria
Prescribing ORBACTIV in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria [see PATIENT INFORMATION].
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Long term studies in animals have not been conducted to determine the carcinogenic potential of oritavancin.
No mutagenic or clastogenic potential of oritavancin was found in a battery of tests, including an Ames assay, in vitro chromosome aberration assay in Chinese hamster ovary cells, in vitro forward mutation assay in mouse lymphoma cells and an in vivo mouse micronucleus assay.
Oritavancin did not affect the fertility or reproductive performance of male rats (exposed to daily doses up to 30 mg/kg for at least 4 weeks) and female rats (exposed to daily doses up to 30 mg/kg for at least 2 weeks prior to mating). Those daily doses would be equivalent to a human dose of 300 mg, or 25% of clinical dose. Higher doses were not evaluated in nonclinical fertility studies.
Use In Specific Populations
There are no available data on ORBACTIV use in pregnant women to evaluate for a drugassociated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. In animal reproduction studies, no effects on embryo-fetal development or survival were observed in pregnant rats or rabbits treated at the highest doses throughout organogenesis with intravenous oritavancin, at doses equivalent to 25% of the single clinical dose of 1200 mg (see Data).
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 estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.
Reproduction studies performed in rats and rabbits have revealed no evidence of harm to the fetus due to oritavancin at the highest doses administered throughout organogenesis, 30 mg/kg/day (gestation days 6-17) and 15 mg/kg/day (gestation days 7-19), respectively. Those doses would be equivalent to a human dose of 300 mg, or 25% of the single clinical dose of 1200 mg. Higher doses were not evaluated in nonclinical developmental and reproductive toxicology studies.
There are no data on the presence of oritavancin in human milk, the effects on the breastfedchild, or the effects on milk production. ORBACTIV is present in the breast milk of rats (see Data). When a drug is present in animal milk, it is likely that the drug will be present in human milk.
The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for ORBACTIV and any potential adverse effects on the breast-fed child from ORBACTIV or from the underlying maternal condition.
Following a single intravenous infusion in lactating rats, radio-labeled [14C]-oritavancin was excreted in milk and absorbed by nursing pups.
Safety and effectiveness of ORBACTIV in pediatric patients (younger than 18 years of age) has not been studied.
The pooled Phase 3 ABSSSI clinical trials of ORBACTIV did not include sufficient numbers of subjects aged 65 and older to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.
No dosage adjustment of ORBACTIV is needed in patients with mild or moderate renal impairment [see DOSAGE AND ADMINISTRATION, CLINICAL PHARMACOLOGY]. The pharmacokinetics of ORBACTIV in severe renal impairment have not been evaluated.
ORBACTIV is not removed from blood by hemodialysis.
No dosage adjustment of ORBACTIV is needed in patients with mild or moderate hepatic impairment. The pharmacokinetics of ORBACTIV in patients with severe hepatic insufficiency has not been studied [see DOSAGE AND ADMINISTRATION, CLINICAL PHARMACOLOGY].
In the ORBACTIV clinical program there was no incidence of accidental overdose of ORBACTIV.
Based on an in vitro hemodialysis study, ORBACTIV is unlikely to be removed from blood by hemodialysis. In the event of overdose, supportive measures should be taken.
Intravenous Unfractionated Heparin Sodium
Use of intravenous unfractionated heparin sodium is contraindicated for 120 hours (5 days) after ORBACTIV administration because the activated partial thromboplastin time (aPTT) test results may remain falsely elevated for up to 120 hours (5 days) after ORBACTIV administration [see WARNINGS AND PRECAUTIONS and DRUG INTERACTIONS].
ORBACTIV is contraindicated in patients with known hypersensitivity to ORBACTIV.
Mechanism Of Action
Oritavancin is an antibacterial drug [see Microbiology].
The antimicrobial activity of oritavancin appears to correlate with the ratio of area under the concentration-time curve to minimal inhibitory concentration (AUC/MIC) based on animal models of infection.
Exposure-response analyses from both preclinical and clinical studies support the treatment of clinically relevant Gram-positive microorganisms (e.g. S. aureus and S. pyogenes) causative of ABSSSI with a single 1200 mg dose of ORBACTIV.
In a thorough QTc study of 135 healthy subjects at a dose 1.3 times the 1200 mg recommended dose, ORBACTIV did not prolong the QTc interval to any clinically relevant extent.
The population PK analysis was derived using data from the two Phase 3 ABSSSI clinical trials in 297 patients. The mean pharmacokinetic parameters of oritavancin in patients following a single 1200 mg dose are presented in Table 3.
Table 3: Mean PK parameters for patients receiving a single 1200 mg dose for ABSSSI (n=297)
|Cmax (μg/mL)||138 (23.0%)|
|AUC0-24 (μg•h/mL)||1110 (33.9%)|
|AUC0-∞ (μg•h/mL)||2800 (28.6%)|
|Cmax, Maximum plasma concentration; AUC0-24, Area under the plasma concentration-time curve from time zero to 24 hours, AUC0-∞ = Area under the plasma concentration time curve from time zero to infinity; CV% = Percent Coefficient of variation.|
Oritavancin exhibits linear pharmacokinetics at a dose up to 1200 mg. The mean, populationpredicted oritavancin concentration-time profile displays a multi-exponential decline with a long terminal plasma half-life.
Oritavancin is approximately 85% bound to human plasma proteins.
Based on population PK analysis, the population mean total volume of distribution is estimated to be approximately 87.6 L, indicating oritavancin is extensively distributed into the tissues.
Exposures of oritavancin in skin blister fluid were approximately 20% of those in plasma (AUC0-24) after single 800 mg dose in healthy subjects.
Non-clinical studies including in vitro human liver microsome studies indicated that oritavancin is not metabolized. No mass balance study has been conducted in humans. In humans, oritavancin is slowly excreted unchanged in feces and urine with less than 1% and 5% of the dose recovered in feces and urine, respectively, after 2 weeks of collection.
Oritavancin has a terminal half-life of approximately 245 hours and a clearance of 0.445 L/h based on population pharmacokinetic analyses.
No dosage adjustments of ORBACTIV are required for patients with mild to moderate renal or mild to moderate hepatic impairment or other subpopulations including age, gender, race and weight.
The pharmacokinetics of oritavancin was examined in the Phase 3 ABSSSI trials in patients with normal renal function, CrCL ≥80 mL/min (n=238), mild renal impairment, CrCL 50-79 mL/min (n=48), and moderate renal impairment, CrCL 30-49 mL/min (n=11). Population pharmacokinetic analysis indicated that mild to moderate renal impairment had no clinically relevant effect on the exposure of oritavancin. No dedicated studies in dialysis patients have been conducted.
Dosage adjustment of ORBACTIV is not needed in patients with mild or moderate renal impairment. The pharmacokinetics of oritavancin in patients with severe renal impairment have not been evaluated.
The pharmacokinetics of oritavancin were evaluated in study of subjects with moderate hepatic impairment (Child-Pugh Class B) (n=20) and compared with healthy subjects (n=20) matched for gender, age and weight. There were no relevant changes in pharmacokinetics of oritavancin in subjects with moderate hepatic impairment.
Dosage adjustment of ORBACTIV is not needed in patients with mild or moderate hepatic impairment. The pharmacokinetics of oritavancin in patients with severe hepatic insufficiency has not been studied.
The pharmacokinetics of ORBACTIV in pediatric populations (<18 years of age) has not been studied [see Use In Specific Populations].
Age, Gender, Weight And Race
Population pharmacokinetic analysis from the Phase 3 ABSSSI trials in patients indicated that gender, age, weight or race had no clinically relevant effect on the exposure of ORBACTIV. No dosage adjustment is warranted in these subpopulations.
In vitro studies with human liver microsomes showed that oritavancin inhibited the activities of cytochrome P450 (CYP) enzymes 1A2, 2B6, 2D6, 2C9, 2C19, and 3A4. The observed inhibition of multiple CYP isoforms by oritavancin in vitro is likely to be reversible and noncompetitive. In vitro studies indicate that oritavancin is neither a substrate nor an inhibitor of the efflux transporter P-glycoprotein (P-gp).
Drugs That Inhibit Or Induce CYP450 Enzymes
A screening drug-drug interaction study was conducted in healthy volunteers (n=16) evaluating the concomitant administration of a single 1200 mg dose of ORBACTIV with probe substrates for several CYP450 enzymes. The results showed that ORBACTIV is a weak inducer of CYP3A4 (a decrease of 18% in the mean AUC of midazolam) and CYP2D6 (decrease of 31% in the ratio of dextromethorphan to dextrorphan concentrations in the urine after administration of dextromethorphan). ORBACTIV was also a weak inhibitor of CYP2C19 (increase of 15% in the ratio of omeprazole to 5-OH-omeprazole concentrations in the plasma after administration of omeprazole) and also showed to be a weak inhibitor of CYP2C9 (with an increase of 31% in the mean AUC of warfarin) [see WARNINGS AND PRECAUTIONS, and DRUG INTERACTIONS].
In the screening drug-drug interaction study, co-administration of ORBACTIV resulted in an increase of 18% in the ratio of 1-methylxanthine + 1 methylurate + 5-acetylamino-6- formylamino-3-methyluracil (1X + 1U + AFMU) to 1,7-dimethylurate (17U) concentrations in the urine after administration of caffeine (CYP1A2 probe substrate), and an increase of 16% in the ratio of AFMU to (1X +1U) concentrations in the urine after administration of caffeine (NAcetyltransferase- 2 probe substrate). Co-administration of ORBACTIV did not change the mean systemic exposure of caffeine metabolite (Xanthine oxidase probe substrate).
A study to assess the drug-drug interaction potential of a single 1200 mg dose of ORBACTIV on the pharmacokinetics of S-warfarin following a single dose was conducted in 36 healthy subjects. S-warfarin pharmacokinetics were evaluated following a single dose of warfarin 25 mg given alone, or administered at the start, 24, or 72 hours after a single 1200 mg ORBACTIV dose. The results showed no effect of ORBACTIV on S-warfarin Cmax or AUC.
ORBACTIV is a semi-synthetic, lipoglycopeptide antibacterial drug. ORBACTIV exerts a concentration-dependent bactericidal activity in vitro against S. aureus, S. pyogenes, and E. faecalis.
Mechanism Of Action
Oritavancin has three mechanisms of action: (i) inhibition of the transglycosylation (polymerization) step of cell wall biosynthesis by binding to the stem peptide of peptidoglycan precursors; (ii) inhibition of the transpeptidation (crosslinking) step of cell wall biosynthesis by binding to the peptide bridging segments of the cell wall; and (iii) disruption of bacterial membrane integrity, leading to depolarization, permeabilization, and cell death. These multiple mechanisms contribute to the concentration-dependent bactericidal activity of oritavancin.
In serial passage studies, resistance to oritavancin was observed in isolates of S. aureus and E. faecalis. Resistance to oritavancin was not observed in clinical studies.
Interaction With Other Antimicrobial Agents
In in vitro studies, oritavancin exhibits synergistic bactericidal activity in combination with gentamicin, moxifloxacin or rifampicin against isolates of methicillin-susceptible S. aureus (MSSA), with gentamicin or linezolid against isolates of heterogeneous vancomycin-intermediate S. aureus (hVISA), VISA, and vancomycin-resistant S. aureus (VRSA), and with rifampin against isolates of VRSA. In vitro studies demonstrated no antagonism between oritavancin and gentamicin, moxifloxacin, linezolid or rifampin.
Oritavancin has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections [see INDICATIONS].
Staphylococcus aureus (including methicillin-resistant isolates)
Streptococcus anginosus group (includes S. anginosus, S. intermedius, and S. constellatus)
Enterococcus faecalis (vancomycin-susceptible isolates only)
The following in vitro data are available but their clinical significance is unknown. At least 90 percent of the following bacteria exhibit an in vitro minimum inhibitory concentration (MIC) less than or equal to the susceptible breakpoint for oritavancin against isolates of a similar organism group. However, the efficacy of oritavancin in treating clinical infections due to these bacteria has not been established in adequate and well-controlled clinical trials.
Enterococcus faecium (vancomycin-susceptible isolates only)
Susceptibility Testing Methods
For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see: https://www.fda.gov/STIC.
Acute Bacterial Skin And Skin Structure Infections (ABSSSI)
A total of 1987 adults with clinically documented ABSSSI suspected or proven to be due to Gram-positive pathogens were randomized into two identically designed, randomized, doubleblind, multi-center, multinational, non-inferiority trials (Trial 1 and Trial 2) comparing a single 1200 mg intravenous dose of ORBACTIV to intravenous vancomycin (1 g or 15 mg/kg every 12 hours) for 7 to 10 days. The primary analysis population (modified intent to treat, mITT) included all randomized patients who received any study drug. Patients could receive concomitant aztreonam or metronidazole for suspected Gram-negative and anaerobic infection, respectively. Patient demographic and baseline characteristics were balanced between treatment groups. Approximately 64% of patients were Caucasian and 65% were males. The mean age was 45 years and the mean body mass index was 27 kg/m2. Across both trials, approximately 60% of patients were enrolled from the United States and 27% of patients from Asia. A history of diabetes was present in 14% of patients. The types of ABSSSI across both trials included cellulitis/erysipelas (40%), wound infection (29%), and major cutaneous abscesses (31%). Median infection area at baseline across both trials was 266.6 cm2. The primary endpoint in both trials was early clinical response (responder), defined as cessation of spread or reduction in size of baseline lesion, absence of fever, and no rescue antibacterial drug at 48 to 72 hours after initiation of therapy.
Table 4 provides the efficacy results for the primary endpoint in Trial 1 and Trial 2 in the primary analysis population.
Table 4: Clinical Response Rates in ABSSSI Trials using Responders1, 2 at 48-72 Hours after Initiation of Therapy
n /N (%)
n /N (%)
|Difference (95% CI)3|
|Trial 1||391/475 (82.3)||378/479 (78.9)||3.4 (-1.6, 8.4)|
|Trial 2||403/503 (80.1)||416/502 (82.9)||-2.7 (-7.5, 2.0)|
|1 Cessation of spread or reduction in size of baseline lesion, absence of fever (<37.7°C) and no rescue antibacterial drug at 48 to 72 hours.|
2 Patients who died at 48 to 72 hours, after initiation of therapy or who had increase in lesion size at 48 to 72 hours, after initiation of therapy or who used non-study antibacterial therapy during first 72 hours or who had an additional, unplanned, surgical procedure or who had missing measurements during the first 72 hours from initiation of study drug were classified as non-responders.
3 95% CI based on the Normal approximation to Binomial distribution.
A key secondary endpoint in these two ABSSSI trials evaluated the percentage of patients achieving a 20% or greater reduction in lesion area from baseline at 48-72 hours after initiation of therapy. Table 5 summarizes the findings for this endpoint in the two ABSSSI trials.
Table 5: Clinical Response Rates1 in ABSSSI Trials using Reduction in Lesion Area of 20% or Greater at 48-72 Hours after Initiation of Therapy
n /N (%)
n /N (%)
|Difference (95% CI)2|
|Trial 1||413/475 (86.9)||397/479 (82.9)||4.1 (-0.5, 8.6)|
|Trial 2||432/503 (85.9)||428/502 (85.3)||0.6 (-3.7, 5.0)|
|1 Patients who died at 48 to 72 hours, after initiation of therapy or who had increase in lesion size at 48 to 72 hours, after initiation of therapy or who used non-study antibacterial therapy during first 72 hours or who had an additional, unplanned, surgical procedure or who had missing measurements during the first 72 hours from initiation of study drug were classified as non-responders.|
2 95% CI based on the Normal approximation to Binomial distribution.
Another secondary efficacy endpoint in the two trials was investigator-assessed clinical success at post therapy evaluation at Day 14 to 24 (7 to 14 days from end of blinded therapy). A patient was categorized as a clinical success if the patient experienced a complete or nearly complete resolution of baseline signs and symptoms related to primary ABSSSI site (erythema, induration/edema, purulent drainage, fluctuance, pain, tenderness, local increase in heat/warmth) such that no further treatment with antibacterial drugs was needed.
Table 6 summarizes the findings for this endpoint in the mITT and clinically evaluable population in these two ABSSSI trials. Note that there are insufficient historical data to establish the magnitude of drug effect for antibacterial drugs compared with placebo at the post therapy visits. Therefore, comparisons of ORBACTIV to vancomycin based on clinical success rates at these visits cannot be utilized to establish non-inferiority conclusions.
Table 6: Clinical Success Rates1 in ABSSSI Trials at the Follow-Up Visit (7-14 days after end of therapy)
n /N (%)
n /N (%)
|Difference (95% CI)2|
|mITT||378/475 (79.6)||383/479 (80.0)||-0.4 (-5.5, 4.7)|
|CE||362/394 (91.9)||370/397 (93.2)||-1.3 (-5.0,2.3)|
|mITT||416/503 (82.7)||404/502 (80.5)||2.2 (-2.6, 7.0)|
|CE||398/427 (93.2)||387/408 (94.9)||-1.6 (-4.9,1.6)|
|1 Clinical success was defined if the patient experienced a complete or nearly complete resolution of baseline signs and symptoms as described above.|
2 95% CI based on the Normal approximation to Binomial distribution.
3 mITT population consisted of all randomized patients who received study drug; CE population consisted of all mITT patients who did not have violations of inclusion and exclusion criteria, completed treatment and had investigator assessment at the Follow-Up Visit.
Outcomes By Baseline Pathogen
Table 7 shows outcomes in patients with an identified baseline pathogen in the microbiological Intent-to-Treat (microITT) population in a pooled analysis of Trial 1 and Trial 2. The outcomes shown in the table are clinical response rates at 48 to 72 hours and clinical success rates at follow-up study day 14 to 24.
Table 7: Outcomes by Baseline Pathogen (microITT)
|At 48-72 hours||Study day 14 to 24|
|Early Clinical Responder1||≥ 20% reduction in lesion size2||Clinical Success3|
|Staphylococcus aureus||388/472 (82.2)||395/473 (83.5)||421/472 (89.2)||407/473 (86.0)||390/472 (82.6)||398/473 (84.1)|
|Methicillinsusceptible||222/268 (82.8)||233/272 (85.7)||231/268 (86.2)||232/272 (85.3)||220/268 (82.1)||229/272 (84.2)|
|Methicillinresistant||166/204 (81.4)||162/201 (80.6)||190/204 (93.1)||175/201 (87.1)||170/204 (83.3)||169/201 (84.1)|
|Streptococcus pyogenes||21/31 (67.7)||23/32 (71.9)||24/31 (77.4)||24/32 (75.0)||25/31 (80.6)||23/32 (71.9)|
|Streptococcus agalactiae||7/8 (87.5)||12/12 (100.0)||8/8 (100.0)||12/12 (100.0)||7/8 (87.5)||11/12 (91.7)|
|Streptococcus dysgalactiae||7/9 (77.8)||6/6 (100.0)||6/9 (66.7)||5/6 (83.3)||7/9 (77.8)||3/6 (50.0)|
|Streptococcus anginosus group||28/33 (84.8)||40/45 (88.9)||29/33 (87.9)||42/45 (93.3)||25/33 (75.8)||38/45 (84.4)|
|Enterococcus faecalis||11/13 (84.6)||10/12 (83.3)||10/13 (76.9)||8/12 (66.7)||8/13 (61.5)||9/12 (75.0)|
|1Early clinical response defined as a composite of the cessation of spread or reduction in size of baseline lesion, absence of fever and no rescue antibacterial drug at 48-72 hours.|
2 Patients achieving a 20% or greater reduction in lesion area from baseline at 48-72 hours after initiation of therapy.
3Clinical success was defined if the patient experienced a complete or nearly complete resolution of baseline signs and symptoms as described above.
4 Baseline bacteremia in the oritavancin arm with relevant microorganisms causing ABSSSI included four subjects with MSSA and seven subjects with MRSA. Eight of these eleven subjects were responders at 48 to 72 hours after initiation of therapy.
Patients should be advised that allergic reactions, including serious allergic reactions, could occur and that serious reactions require immediate treatment. They should inform their healthcare provider about any previous hypersensitivity reactions to ORBACTIV, other glycopeptides (vancomycin, telavancin, or dalbavancin) or other allergens.
Patients should be advised that diarrhea is a common problem caused by antibacterial drugs including ORBACTIV, which usually resolves when the drug is discontinued. Sometimes, frequent watery or bloody diarrhea may occur and may be a sign of a more serious intestinal infection. If severe watery or bloody diarrhea develops, patients should contact their healthcare provider.
Development Of Antibacterial Resistance
Patients should be counseled that antibacterial drugs including ORBACTIV should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold). When ORBACTIV is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by ORBACTIV or other antibacterial drugs in the future.
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