Antimycobacterials Flashcards
What are mycobacterials?
rodlike gram (+) aerobic bacteria that can form filamentous branching structures
Infections caused by mycobacteria are hard to treat. Why?
- mycobacteria grow slowly
- can lie dormant
- cell walls are thick and impermeable so hard to attain access intracellularly
- can reside inside host cells making it more difficult to reach therapeutic levels
- become resistant to antibiotic quickly
How should you treat mycobacteria (generally)? why?
- long periods
- several different antibiotics simultaneously
will help prevent emergence of resitant strains
Name the drugs that treat mycobacterial infections
- isonaizid
- rifampin
- pyrazinamide
- ethambutol
- clofazimine
What is the mechanism of action for isoniazid?
isoniazid inhibits synthesis of mycolic acids (essential component of mycobacterial cell walls)
Describe the distribution and metabolism patterns of isoniazid
distribution=> total body water including CNS
metabolism => acetylation
what do genetics play in the acetylation process for isoniazid? who is at greater risk?
fast => may not reach therapeutic levels and have short plasma half-life
slow=> at greater risk for drug-related toxicities due to long half life
What is the mechanism of action for rifampin?
inhibits bacterial RNA polymersase
this prevents transcription by suppressing initiation of RNA chain formation
Why is rifampin associated interaction a major concern?
rifampin is a potent inducer of drug metabolism and alters plasma levels of many drugs
How might pyrazinamide work?
lower the pH in tubercle cavity to inhibit growth of mycobacterium
What is the mechanism of action for ethambutol?
inhibits RNA synthesis and decreases replication of tubercle bacilli
What is the mechanism of action of clofazimine? what is the speed of the drug?
- bind to mycobacterial DNA
- inhibits RNA polymerase actions
activities are very slow and patients are treated for a minimum of 2 years and possibly for life
