Protein Syntheis inhibitors Flashcards
Which Drug and adverse effect pairing is correct? She likes these types of questions**
A erythromycin : CNS toxicity
B. Chloramphenicol : cholestatic hepatitis
C. gentamicin : gray baby syndrome
D. doxycycline : tooth discoloration
E. mupirocin : renal toxicity
D
what ribosome subunits do bacteria use?
50s and 30s. (70s ribosome-similar to mitochondria - toxicity)
Tetracyclins, Tigecycline, Aminoglycosides, and Spectinomycin all act on what?
30S ribosome
Most protein synthesis inhibitors are
bacteriostatic, given orally, and broad spectrum
Tetracylcines
bind to 30S. very broad; superinfections! bacteriostatic
Tetracyclines cont.
decrease by divalent and trivalent cations (Fe and K) so they shouldn’t have food at same time. absorption is decreased when pH is elevated.
Which is False. Tetracyclines have narrow distribution, have good penetration into the CNS, and are deposited in bone, dentine, and enamel
They have a WIDE distribution in the body
Doxycyclines and monocyclines are always the exception to tetracyclines
namely they are eliminated in the feces so they don’t have an impact on the normal flora=makes them safer
Uses of tetracyclines
Acne, Drug of choice for treatment of rickettsial disease
Adverse effects of tetracyclines
pseudomembranous colitis, discoloration of teeth and fetal childhood risks, bluing of tissue, DO NOT give to pregnant women and children
tetracyclines should be used with cidal antibiotics like penicills. true or false
false. drug interactions between tetracycline and bacteriocidal drugs.
Tigecycline
similar mechanism of action to tetracyclines, but binds higher affinity to 30s ribosome. . used for strains that are tetracycline resistant and some MRSA.
Aminoglycosides
Gentamicin. ***Bactericidal! bind irreversible to 30S ribosome. concentration dependent killing with significant PAE (uncommon)
Uses of Aminoglycosides
Primarily gram negative aerobic bacilli. synergistic Combination therapy with penicillin or vancomycin (acts synergistically on staph aureus and epidermidis
Toxicities of Aminoglycosides
Ototoxicity (irreversible loss of hearing) and renal toxicities. also vestibular toxicities
Gentamicin
aminoglycoside. resistance is due to poor drug uptake. synergistic with penicillins and vancomycin. Main use is SEVERE gram - infections. ototoxicity, vestibular, and renal damage
What is false about spectinomycin
It binds to the 50S subunit
It works mostly on gram negatives but some gram + as well.
Main use is for antibiotic resistant gonorrhea and MRSA
It is bacteriostatic
It works on the 30S subunit, not the 50S.
What class are azithromycin, erythromycin, and clarithromycin in?
Macrolides. erythromycin is founding member. azi and clar have better distribution and absorption
Macrolide target
50S subunit very close to same site as streptogramin, slindamycin, and chloramphenicol. Competitively inhibits them/Antagonism
What is false about macrolides Binds reversibly to the 50S subunit its bacteriostatic Have a broad spectrum of activity Organisms build rapid cross-resistance to it
They have a narrow spectrum of activity.
MLS-type B resistance
macrolide lincosamide streptogramin. expresses methylase that modifies the bacterial ribosome and drug is unable to bind
Erythromycin
not acid stable like the other macrolides (azithromycin, clarithromycin),
Uses of macrolides
good substitution for penicillins in allergic patients. Also acne.
what is the key weakness of the macrolides?
resistance develops rapidly
