CH3 | Protein Synthesis Inhibitors (Streptogramins) Flashcards
What are the two components of Streptogramins?
Quinupristin and dalfopristin in a 30:70 ratio.
What is the mechanism of action of Streptogramins?
Each component binds to separate sites on the 50S bacterial ribosome.
How does dalfopristin affect protein synthesis?
It disrupts elongation by interfering with the addition of new amino acids to the peptide chain.
What role does quinupristin play in protein synthesis?
It prevents elongation similar to macrolides and causes the release of incomplete peptide chains.
What is the effect of the synergistic action of Streptogramins?
It is bactericidal and has a long post-antibiotic effect (PAE).
What types of infections are Streptogramins used to treat?
Severe infections caused by vancomycin-resistant Enterococcus (VRE) in the absence of other therapeutic options.
What are the resistance mechanisms to Streptogramins?
Enzymatic processes, target site methylation, plasmid-associated acetyltransferase, and efflux pumps.
How does target site methylation contribute to Streptogramin resistance?
It interferes with quinupristin binding.
What role does plasmid-associated acetyltransferase play in Streptogramin resistance?
It inactivates dalfopristin.
What is the method of administration for Streptogramins?
Intravenous (IV).
Do Streptogramins achieve therapeutic concentrations in cerebrospinal fluid (CSF)?
No, they do not achieve therapeutic concentrations in CSF.
How are Streptogramins metabolized and excreted?
They undergo hepatic metabolism and are excreted in feces.
What are the adverse side effects associated with Streptogramins?
- Venous irritation.
- Hyperbilirubinemia.
- Arthralgia and myalgia when used in high doses.
- Cytochrome P450 CYP3A4 isoenzymes inhibition, resulting in drug-drug interactions.
What condition can Streptogramins cause related to bilirubin?
Hyperbilirubinemia.
What is adverse effect associated with high doses of Streptogramins?
Arthralgia and myalgia.
