Pharmacology
Summary
Daptomycin is a cell wall-active antibiotic effective against gram-positive bacteria, particularly those resistant to other treatments. It uses calcium ions to disrupt the bacterial membrane potential and inhibit DNA, RNA, and protein synthesis, and it also demonstrates efficacy against severe infections caused by MRSA and MSSA.
Daptomycin specifically uses two free calcium ions to insert its lipid tail into the bacterial cell wall, which creates a little channel for rapid ion flux. The cell membrane depolarizes, potassium ions flow out of the cell, and subsequently, all potassium-dependent DNA, RNA and protein synthesis come to a halt, and the cell dies.
The range of activity of daptomycin is comparable to that of vancomycin, and it is proficient in targeting gram-positive bacteria like streptococcus, staphylococcus, and enterococcus species. However, it is also effective against vancomycin-resistant enterococcus, bacteremia caused by MRSA and MSSA, and other complicated skin infections.
Daptomycin, however, is contraindicated for pneumonia, because surfactant inactivates the drug. Among its potential side effects, daptomycin can trigger rhabdomyolysis, a condition involving the breakdown of muscle tissue, which mandates the monitoring of CPK levels before and during treatment. Other side effects could arise, such as peripheral neuropathy and eosinophilic pneumonitis, which is a rare but serious allergic response to the drug.
Lesson Outline
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FAQs
Daptomycin is a bactericidal, cell wall-active antibiotic. It operates by inserting its charged lipid tail into the bacterial cell wall, which results in ion flux and rapid depolarization, causing a cessation in potassium-dependent DNA, RNA, and protein synthesis. This sequence effectively ends the life of the bacterial cell.
Daptomycin's spectrum of activity resembles that of vancomycin and includes many gram-positive bacteria, such as staphylococcus, streptococcus, and enterococcus. It also showcases effectiveness against vancomycin-resistant bacterial strains and is active against Staphylococcus aureus, including MSSA and MRSA.
Daptomycin is primarily used to treat MRSA (and MSSA) bacteremia, tricuspid valve endocarditis, and complicated cases of skin infections. However, it should not be considered for pulmonary infections as the drug is inactivated by surfactant.
Daptomycin can have harmful effects on muscle tissue, and potentially cause myopathy and rhabdomyolysis. Monitoring creatine phosphokinase (CPK) levels weekly is suggested for patients receiving prolonged therapy. Daptomycin use can also result in peripheral neuropathy manifesting as numbness, burning, or tingling of the hands and feet (i.e., stocking and glove distribution). There's also a risk of eosinophilic pneumonia due to daptomycin use.
