Cubicin Drug Interactions

Interactions with Other Medicinal Products: CUBICIN was studied in adult human drug-drug interaction studies with aztreonam, tobramycin, warfarin, simvastatin, and probenecid. Daptomycin had no effect on the pharmacokinetics of warfarin or probenecid, nor did these drugs alter the pharmacokinetics of daptomycin. The pharmacokinetics of daptomycin were not significantly altered by aztreonam.
Experience with the concomitant administration of CUBICIN and warfarin is limited. Studies of CUBICIN with anticoagulants other than warfarin have not been conducted. Monitor anticoagulant activity in patients receiving CUBICIN and warfarin for the first several days after therapy with CUBICIN is initiated.
Experience with the coadministration of HMG-CoA reductase inhibitors and CUBICIN in patients is limited; therefore, consider suspending use of HMG-CoA reductase inhibitors temporarily in patients receiving CUBICIN.
Although small changes in the pharmacokinetics of daptomycin and tobramycin were observed during coadministration by IV infusion over a 30-minute period using a CUBICIN dose of 2 mg/kg, the changes were not statistically significant. The interaction between daptomycin and tobramycin with a clinical dose of CUBICIN is unknown. Caution is warranted when CUBICIN is coadministered with tobramycin.
Drug-Laboratory Test Interactions: Clinically relevant plasma concentrations of daptomycin have been observed to cause a significant concentration-dependent false prolongation of prothrombin time (PT) and elevation of International Normalized Ratio (INR) when certain recombinant thromboplastin reagents are utilized for the assay. The possibility of an erroneously elevated PT/INR result due to interaction with a recombinant thromboplastin reagent may be minimized by drawing specimens for PT or INR testing near the time of trough plasma concentrations of daptomycin. However, sufficient daptomycin concentrations may be present at trough to cause interaction.
If confronted with an abnormally high PT/INR result in a patient being treated with CUBICIN, it is recommended that clinicians: Repeat the assessment of PT/INR, requesting that the specimen be drawn just prior to the next CUBICIN dose (i.e., at trough concentration). If the PT/INR value obtained at trough remains substantially elevated above what would otherwise be expected, consider evaluating PT/INR utilizing an alternative method.
Evaluate for other causes of abnormally elevated PT/INR results.