No Clinically Significant Interaction Between Metoprolol and Daptomycin
Metoprolol (Metrol dose pack) does not interfere with daptomycin—these medications can be safely co-administered without dose adjustments or special monitoring beyond what is already indicated for each drug individually.
Evidence Basis
The FDA drug label for daptomycin explicitly addresses drug-drug interactions and demonstrates no involvement with the cytochrome P450 system 1. Daptomycin does not inhibit or induce CYP450 isoforms (1A2, 2A6, 2C9, 2C19, 2D6, 2E1, and 3A4), which are the primary metabolic pathways for most medications including metoprolol 1.
Key Pharmacologic Considerations:
Daptomycin metabolism: Daptomycin is renally excreted and does not undergo hepatic metabolism via CYP450 enzymes 1, 2
Metoprolol metabolism: Metoprolol is primarily metabolized through CYP2D6 3, but since daptomycin has no effect on this pathway, no interaction occurs
Documented drug interactions with daptomycin: The FDA label specifically studied and documented interactions only with aztreonam, tobramycin, warfarin, simvastatin, and probenecid—none of which showed clinically significant alterations in daptomycin pharmacokinetics 1
Clinical Implications
When prescribing these medications together:
- No dose adjustment needed for either medication based on the co-administration
- Continue standard monitoring for daptomycin (weekly CPK levels for myopathy risk, especially if patient is also on statins) 4
- Continue standard monitoring for metoprolol (heart rate, blood pressure, signs of heart failure)
- No additional drug interaction monitoring is required specifically for this combination
Important Caveat
While metoprolol does not interact with daptomycin, be aware that daptomycin does have a documented interaction with HMG-CoA reductase inhibitors (statins) regarding increased risk of skeletal myopathy 1. If your patient is on both metoprolol and a statin, the statin interaction with daptomycin requires attention, but this is unrelated to the metoprolol.