Mehanism of action and spectrum:
Daptomycin binds to the cell membrane of gram-positive bacteria, weakening it and allowing essential ions to leak out of the organism. This leads to a rapid depolarization of the membrane potential and cessation of needed cell processes, leading to cell death. Instead of blowing the bacteria apart as beta lactams do, daptomycin leaves the dead bacteria intact.
Lipid portion of the drug inserts into the cell membrane of gram-positive organisms, leading to the leakage of intracellular cations that maintain membrane polarization. The result is rapid depolarization and cell death. Daptomycin is active against many resistant gram-positive organisms, including VRE and MRSA. It has been proven effective in staphylococcal endocarditis (specifically right-sided endocarditis), an indication that few antibiotics have. Though it penetrates lung tissue very well, daptomycin cannot be used to treat pneumonia. Human pulmonary surfactant binds to daptomycin, rendering it inactive.
Uses:
is effective for treating complicated skin and soft tissue infections. It is administered intravenously once daily and is excreted unchanged in urine; dose adjustments are required when given to individuals with severe renal insufficiency
Adverse effects:
Daptomycin has effects on skeletal muscle that can manifest (rarely) as muscle pain or weakness, or possibly rhabdomyolysis. To monitor for this effect, creatine kinase (CK) concentrations should be checked weekly while a patient is on therapy. This toxicity can be decreased by administering the drug no more than once daily and by adjusting the interval in renal dysfunction. Eosinophilic pneumonia has been reported in patients on daptomycin therapy