Daptomycin

Daptomycin: Overview

Daptomycin is a lipopeptide antibiotic primarily used for treating serious Gram-positive infections, especially when resistance is present. It is often used for VRE infections or replacement of Vancomycin due to convenient once daily dosing. 

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Spectrum:

• Gram-positive:
  • Broad coverage, including:
    • MSSA (Methicillin-sensitive Staphylococcus aureus)
    • MRSA (Methicillin-resistant Staphylococcus aureus)
    • Streptococcus species
    • VRE (Vancomycin-resistant Enterococcus faecium and faecalis)
• Gram-negative: No coverage
• Anaerobes: No significant coverage

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Key Uses:

• Bacteremia and endocarditis caused by MRSA and VRE.
• Treatment of complicated skin and soft tissue infections due to Gram-positive bacteria, particularly MRSA.
• Used when vancomycin cannot be used, especially in patients with vancomycin-resistant enterococci (VRE) or vancomycin-intermediate or resistant MRSA (VISA/VRSA).
• It is not effective in pneumonia because Daptomycin is inactivated by lung surfactant, limiting its use in respiratory infections. (Dapto No No for Pneumonia!)

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Key Notes:

• Inactivation in the lungs: Daptomycin is ineffective in treating lung infections (pneumonia) because it is inactivated by surfactant in the alveoli.
• Monitor for muscle toxicity: Prolonged use of Daptomycin can cause myopathy and rhabdomyolysis. It’s essential to monitor creatine phosphokinase (CPK) levels weekly to check for muscle damage.
• Once-daily dosing: Daptomycin is usually administered once daily via IV, which makes it convenient for inpatient treatment.
• No renal adjustment needed in mild impairment, but dosing adjustments is necessary in severe renal dysfunction.

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Mechanism of Action:

• Daptomycin works by disrupting bacterial cell membranes through calcium-dependent insertion of its lipid tail, leading to rapid depolarization of the membrane. This results in bacterial cell death due to the loss of membrane potential and failure to synthesize essential proteins.

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Common Indications:

• MRSA bacteremia and endocarditis: When vancomycin or other treatments are not effective.
• Complicated skin and soft tissue infections: Effective against resistant Gram-positive organisms.
• VRE infections: Particularly for bloodstream infections caused by vancomycin-resistant enterococci.

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Summary:

• Daptomycin is a crucial antibiotic for serious Gram-positive infections, especially MRSA and VRE, where other treatments might fail.
• It is not suitable for lung infections due to inactivation by surfactant.
• Monitoring for muscle toxicity is important during prolonged therapy.

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