Antibiotics used for Tuberculosis Flashcards
Why is TB hard to treat?
it is slow growing. It is intracellular It develops resistance quickly Patient compliance Drug Toxicity
What are the first-line therapies for M. tuberculosis?
Combo of Isoniazid, Rifampin, pyrazinamide, and ethambutol (or streptomycin).
What are the first-line therapies for M. Avium complex?
clarithromycin and ethambutol (or clofazimine or ciprofloxacin or amikacin)
What is most effective treatment for Latent TB?
INH-RPT with direct observed therapy.
Who is INH-RPT not recommended for?
children < 2 years of age and HIV patients on HAART
What is the MOA of isoniazid?
interferes with mycolic acid synthesis. Bacteriostatic. Penetrates host cells so good for intracellular.
What is the primary elimination route of isoniazid?
Metabolized in liver. 75% excreted in urine. No dosage adjustment necessary for renal failure.
What are the main adverse effects of isoniazid?
Hand-foot neuropathy. Hepatotoxicity. Give Vitamin B6 supplements to prevent Hand-foot neuropathy.
What are contraindications of isoniazid?
Can’t give with antacids containing Al.
What is the MOA of rifampin? Resistance?
inhibition of RNA synthesis, binds B subunit of RNA polymerase. Bactericidal.
Resistance if DNA-dependent RAN polymerase does not bind drug. Effective against slow growing and rapidly dividing cells. First line drug for TB
What are the main adverse effects of rifampin drugs?
discolors body fluid to orange-red. Hepatotoxicity, P450 interactions. No adjustment needed for renal failure.
What is the MOA of ethambutol? Resistance?
inhibition of RNA synthesis. Disruption of cell wall synthesis by inhibiting arabinosyl transferase.
Bacteriostatic. Bacilli MUST be rapidly dividing. Not good for latent phase.
What is the most active antileprosy drug?
Rifampin - inhibition of RNA synthesis by binding B subunit of RNA polymerase.
What are the main adverse effects of ethambutol? Any contraindications?
optic neuritis (vision problems) and hyperuricemia. Cant give with antacids.
What is MOA of pyrazinamide?
Bacilli convert pyrazinamide to pyrazinoic acid and this decreases pH below growth threshold. Cidal and static. Active against tubercle bacilli intracellularly.
What are main adverse effects of pyrazinamide?
hepatotoxicity, non-gouty arthralgia, hyperuricemia. Must stop is gout occurs.
What is MDR TB?
resistant to the two best antibiotics, isoniazid and rifampin.
What is the MOA of cycloserine?
broad spectrum, second line agent. Blocks cell wall synthesis. It is a structural analog of D-alanine. cidal or static. Not protein bound.
What are main adverse effects of cycloserine?
CNS problems and suicidal tendencies. Contraindicated in history of epilepsy.
What is XDR TB?
resistant to two best antibiotics, INH and RIF, as well as most of the alternative drugs.
