TELAVANCIN Drug Interactions: What You Need to Know

INTERACTIONS

7.1 Drug-Laboratory Test Interactions Effects of Telavancin on Coagulation Test Parameters Telavancin binds to the artificial phospholipid surfaces added to common anticoagulation tests, thereby interfering with the ability of the coagulation complexes to assemble on the surface of the phospholipids and promote clotting in vitro . These effects appear to depend on the type of reagents used in commercially available assays. Thus, when measured shortly after completion of an infusion of VIBATIV, increases in the PT, INR, aPTT, and ACT have been observed. These effects dissipate over time, as plasma concentrations of telavancin decrease.

Urine Protein Tests

Telavancin interferes with urine qualitative dipstick protein assays, as well as quantitative dye methods (e.g., pyrogallol red-molybdate). However, microalbumin assays are not affected and can be used to monitor urinary protein excretion during VIBATIV treatment.

Intravenous Unfractionated Heparin Sodium ( 4.1 , 5.5 , 7.1 ) Known hypersensitivity to VIBATIV ( 4.2 , 5.6 , 6.2 )

4.1 Intravenous Unfractionated Heparin Sodium Use of intravenous unfractionated heparin sodium is contraindicated with VIBATIV administration because the activated partial thromboplastin time (aPTT) test results are expected to be artificially prolonged for 0 to 18 hours after VIBATIV administration [ see Warnings and Precautions ( 5.5 ) and Drug Interactions ( 7.1 ) ].

4.2 Known Hypersensitivity to VIBATIV VIBATIV is contraindicated in patients with known hypersensitivity to telavancin.

AND PRECAUTIONS Decreased efficacy among patients treated for skin and skin structure infections with moderate/severe pre-existing renal impairment: Consider these data when selecting antibacterial therapy for patients with baseline CrCl ≤50 mL/min. ( 5.2 ) Coagulation test interference: Telavancin interferes with some laboratory coagulation tests, including prothrombin time, international normalized ratio, and activated partial thromboplastin time. ( 5.5 , 7.1 ) Hypersensitivity reactions: Serious and potentially fatal hypersensitivity reactions, including anaphylactic reactions, may occur after first or subsequent doses. VIBATIV should be used with caution in patients with known hypersensitivity to vancomycin. ( 5.6 , 6.2 ) Infusion-related reactions: Administer VIBATIV over at least 60 minutes to minimize infusion-related reactions. ( 5.7 ) Clostridium difficile -Associated Diarrhea: May range from mild diarrhea to fatal colitis. Evaluate if diarrhea occurs. ( 5.8 ) QTc prolongation: Avoid use in patients at risk. Use with caution in patients taking drugs known to prolong the QT interval. ( 5.10 )

5.1 Increased Mortality in Patients with HABP/VABP and Pre-existing Moderate to Severe Renal Impairment (CrCl ≤50 mL/min) In the analysis of patients (classified by the treatment received) in the two combined HABP/VABP trials with preexisting moderate/severe renal impairment (CrCl ≤50 mL/min), all-cause mortality within 28 days of starting treatment was 95/241 (39%) in the VIBATIV group, compared with 72/243 (30%) in the vancomycin group. Allcause mortality at 28 days in patients without pre-existing moderate/severe renal impairment (CrCl >50 mL/min) was 86/510 (17%) in the VIBATIV group and 92/510 (18%) in the vancomycin group. Therefore, VIBATIV use in patients with baseline CrCl ≤50 mL/min should be considered only when the anticipated benefit to the patient outweighs the potential risk [ see Adverse Reactions ( 6.1 ), Use in Specific Populations ( 8.4 ) and Clinical Studies ( 14.2 ) ].

5.2 Decreased Clinical Response in Patients with cSSSI and Pre-existing Moderate/Severe Renal Impairment (CrCl ≤50 mL/min) In a subgroup analysis of the combined cSSSI trials, clinical cure rates in the VIBATIV-treated patients were lower in patients with baseline CrCl ≤50 mL/min compared with those with CrCl >50 mL/min ( Table 2 ). A decrease of this magnitude was not observed in vancomycin-treated patients. Consider these data when selecting antibacterial therapy for use in patients with cSSSI and with baseline moderate/severe renal impairment.

Table

2: Clinical Cure by Pre-existing Renal Impairment – Clinically Evaluable Population VIBATIV % (n/N) Vancomycin % (n/N) cSSSI Trials CrCl >50 mL/min 87.0% (520/598) 85.9% (524/610) CrCl ≤50 mL/min 67.4% (58/86) 82.7% (67/81)

5.3 Nephrotoxicity In both the HABP/VABP trials and the cSSSI trials, renal adverse events were more likely to occur in patients with baseline comorbidities known to predispose patients to kidney dysfunction (pre-existing renal disease, diabetes mellitus, congestive heart failure, or hypertension). The renal adverse event rates were also higher in patients who received concomitant medications known to affect kidney function (e.g., non-steroidal anti-inflammatory drugs, ACE inhibitors, and loop diuretics). Monitor renal function (i.e., serum creatinine, creatinine clearance) in all patients receiving VIBATIV. Values should be obtained prior to initiation of treatment, during treatment (at 48- to 72-hour intervals or more frequently, if clinically indicated), and at the end of therapy. If renal function decreases, the benefit of continuing VIBATIV versus discontinuing and initiating therapy with an alternative agent should be assessed [ see Dosage and Administration ( 2 ), Adverse Reactions ( 6 ), and Clinical Pharmacology ( 12.3 ) ]. In patients with renal dysfunction, accumulation of the solubilizer hydroxypropyl-beta-cyclodextrin can occur [ see Patients with Renal Impairment ( 8.6 ) and Clinical Pharmacology ( 12.3 ) ].

5.4 Embryo-Fetal Toxicity Based on findings in animal reproduction studies, VIBATIV may cause fetal harm. VIBATIV caused adverse developmental outcomes in 3 animal species at clinically relevant doses. Verify pregnancy status in females of reproductive potential prior to initiating VIBATIV. Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with VIBATIV and for 2 days after the final dose [ see Use in Specific Populations ( 8.1 , 8.3 ) ].

5.5 Coagulation Test Interference Although telavancin does not interfere with coagulation, it interfered with certain tests used to monitor coagulation ( Table 3 ), when conducted using samples drawn 0 to 18 hours after VIBATIV administration for patients being treated once every 24 hours. Blood samples for these coagulation tests should be collected as close as possible prior to a patient's next dose of VIBATIV. Blood samples for coagulation tests unaffected by VIBATIV may be collected at any time [ see Drug Interactions ( 7.1 ) ]. For patients who require aPTT monitoring while being treated with VIBATIV, 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

3: Coagulation Tests Affected and Unaffected by Telavancin Affected by Telavancin Unaffected by Telavancin Prothrombin time/international normalized ratio Activated partial thromboplastin time Activated clotting time Coagulation based factor X activity assay Thrombin time Whole blood (Lee-White) clotting time Platelet aggregation study Chromogenic anti-factor Xa assay Functional (chromogenic) factor X activity assay Bleeding time D-dimer Fibrin degradation products No evidence of increased bleeding risk has been observed in clinical trials with VIBATIV. Telavancin has no effect on platelet aggregation. Furthermore, no evidence of hypercoagulability has been seen, as healthy subjects receiving VIBATIV have normal levels of D-dimer and fibrin degradation products.

5.6 Hypersensitivity Reactions Serious and sometimes fatal hypersensitivity reactions, including anaphylactic reactions, may occur after first or subsequent doses. Discontinue VIBATIV at first sign of skin rash, or any other sign of hypersensitivity. Telavancin is a semi-synthetic derivative of vancomycin; it is unknown if patients with hypersensitivity reactions to vancomycin will experience cross-reactivity to telavancin. VIBATIV should be used with caution in patients with known hypersensitivity to vancomycin [ see Postmarketing Experience ( 6.2 ) ].

5.7 Infusion-Related Reactions VIBATIV is a lipoglycopeptide antibacterial agent and should be administered over a period of 60 minutes to reduce the risk of infusion-related reactions. Rapid intravenous infusions of the glycopeptide class of antimicrobial agents can cause “Red-man Syndrome”-like reactions including: flushing of the upper body, urticaria, pruritus, or rash. Stopping or slowing the infusion may result in cessation of these reactions.

5.8 Clostridium difficile -Associated Diarrhea Clostridium difficile -associated diarrhea (CDAD) has been reported with nearly all antibacterial agents and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the 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. Hyper-toxin-producing strains of C. difficile cause increased morbidity and mortality, since these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibiotic 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, ongoing antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile , and surgical evaluation should be instituted as clinically indicated.

5.9 Development of Drug-Resistant Bacteria Prescribing VIBATIV in the absence of a proven or strongly suspected bacterial infection is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria. As with other antibacterial drugs, use of VIBATIV may result in overgrowth of nonsusceptible organisms, including fungi. Patients should be carefully monitored during therapy. If superinfection occurs, appropriate measures should be taken.

5.10 QTc Prolongation In a study involving healthy volunteers, doses of 7.5 and 15 mg/kg of VIBATIV prolonged the QTc interval [ see Clinical Pharmacology ( 12.2 ) ]. Caution is warranted when prescribing VIBATIV to patients taking drugs known to prolong the QT interval. Patients with congenital long QT syndrome, known prolongation of the QTc interval, uncompensated heart failure, or severe left ventricular hypertrophy were not included in clinical trials of VIBATIV. Use of VIBATIV should be avoided in patients with these conditions.