Antibiotics III: Inhibitors of Protein Synthesis Flashcards
Macrolide drug
Azithromycin (Z-pak)
Macrolides are bacteriocidal/bacteriostatic
Bacteriostatic (can become bactericidal at high concentrations)
Macrolides are excreted ____
In bile/feces
Macrolides are _____ inhibitors
CYP3A4
Adverse reactions of Macrolides
GI irritation
Hepatotoxicity
Prolonged Q-T interval
Lincosamide drug
Clindamycin
Clindamycin MOA
Binds 50S to block peptide bond formation
Bacteriostatic
Clindamycin penetrates well into ____ and ____
Bone; abscessed tissue
Boxed warming of Clindamycin
C. diff colitis/diarrhea
Oxazolidinone drug
Linezolid
Linezolid MOA
Binds to 23S rRNA of 50S subunit to block formation of initiation complex
Linezolid can be used to treat drug-resistant infections but is limited by its ______
Toxicity
Adverse effects of Linezolid
Myelosuppression (check CBC weekly)
Neuropathy
Lactic acidosis
Boxed warning for Linezolid
Inhibits MAO; avoid use with antidepressants
Can cause lethal serotonin syndrome
Inhibition of ribosomal function is bacteriostatic, not bacteriocidal, except for which protein synthesis inhibitor class?
Aminoglycosides (cause mRNA miscoding)
Why do protein synthesis inhibitors have selective toxicity?
They bind with higher affinity to bacterial 70S ribosomes than mammalian 80S ribosomes
Aminoglycoside drug
Gentamicin
Aminoglycosides are highly polar and positive/negative charged
Positive
Aminoglycosides are bacteri____ and active against G_ bacilli
Bactericidal
Aerobic G- bacilli
Aminoglycosides reach cytosol of bacteria by ____ and ____
Filtration through porins
O2 dependent transport across membrane
Post-antibiotic effect
Residual activity after drug falls below MIC
Most antibiotics should be dosed according to ___ body weight
Ideal (doesn’t distribute through fat well)
Gentamicin adverse effects
Nephrotoxicity
Ototoxicity (tinnitus and hearing loss)
Is it better to give one large dose of gentamicin or 3 smaller doses per day?
1 large dose (longer “washout” time limits ototoxicity)
Tetracycline drug
Doxycycline
Doxycycline MOA
Actively transported into bacterial cells; binds to 30S ribosomal subunit and prevents addition of amino acids
Tetracyclines are very broad/narrow spectrum
Broad (includes tick-born illnesses and malaria)
Tetracycline drug interactions
Dairy
Iron supplements
Mg-laxatives
Antacids
Tetracycline adverse reactions
GI upset
Photosensitivity
Deposits into developing bone and teeth (discoloration)
All tetracyclines except ___ should be avoided in pregnant people and children <8
Doxycycline
