L6 Cushman Flashcards
T or F:
lincomycin has antibiotic activity
true but not used bc tox
clindamycin MOA
inhibit protein synthesis by binding to 50S
T or F:
there is no cross-resistance b/w clindamycin and erythromycin
F, there is
Clindamycin effective against _____
AErobic GP Cocci
ANaerobic GN bacilli
(both most common morphologies)
T or F:
Clindamycin can treat MRSA
true
life threatening toxicity of clindamycin
pseudomembranous colitis
clindamycin dosage forms
IV, topical foams, topical solutions, capsules, suspensions
how is clindamycin metabolized
by cyp p450 enzymes in the liver
T or F:
Clindamycin penetrates the CSF with ease
true actually
two treatment options for pseudomembranous colitis from clindamycin
metronidazole or vancomycin
T or F:
tetracycline is broad spectrum
true
what is the relationship between metal ions and tetracyclines
tetracyclines form stable chelates with metal ions
dont give tetracyclines with what
milk, food w/ calcium, tums, hema-anything
if you HAVE to have concomitant therapy with tetracyclines and metals cant be avoided what do you do
metal 1 hour before OR 2 hours after to stop chelation
what weird thing can tetracyclines cause if given to not-fully-developed people
permanently brown or grey teeth since they chelate calcium during tooth formation
T or F:
you can give tetracyclines during pregnancy
true, but avoid after 4th month
how do old tetracyclines lose half their potency
epimerization
Epimerization is _____ in the solid state and ______ in solution at ph4
slow, rapid
where can dehydration occur in tetracyclines
benzylic hydroxyl group at C-6
dehydration of tetracyclines produces a toxic metabolite, what is it called and what can it produce?
4-epianhydrotetracycline, Falconi-like syndrome that can be fatal
which tetracyclines are completely free of a dehydration reaction and why does this happen?
Doxycycline, Minocycline, and tigecycline they lack a C-6 hydroxyl group
When do tetracyclines undergo cleavage
pH values over 8.5
Tetracyclines MOA
bind to 30S ribosomal subunit and inhibit bacterial protein synthesis by blocking attachment of the aminoacyl-tRNA to the A SITE of ribosome, this terminates peptide chain growth
T or F:
tetracycline binding sites overlap with erythromycin binding sites
false
how many different locations on the small ribosomal subunit do tetracyclines bind to
6
T or F:
tetracyclines are broad spectrum
true
most common use of tetracyclines
acne
tetracyclines also treatment of choice for infections cause by?
chlamydia
Difference in structure between tetracycline and demeclocycline
demec has a secondary hydroxyl at C6 instead of tertiary, this makes it dehydrate slower because the cation intermediate is less stable (higher energy)
“tetracycline of choice”
doxycycline
Which tetracycline has a long half life that permits once a day dosing
doxycycline shit also sarecycline
T or F:
sarecycline can cause fetal harm to a pregnant woman
true
why should sarecycline not be administered with oral retinoids
bc both can cause increased intracranial pressure
sarecycline dosage reduction is recommended with what drug class
anticoagulants
Chloramphenicol moa
binds reversibly to 50S, inhibits peptidyl transferase activity and blocks peptide bond formation between P and A site
3 resistance mechs for chloramphenicol
1) reduced membrane permeability
2) mutation of 50S
3) elaboration of chloramphenicol acetyltransferase, acetylates hydroxy group(s) to form metabolites that do NOT bind 50S
chloramphenicol metabolism
metabolized to glucuronide in the liver
most serious toxicity of chloramphenicol
aplastic anemia, fatal, more likely with oral and lowest risk with eye drops
T or F:
chloramphenicol inhibits cyp p450
true
T or F:
chloramphenicol reaches CSF
true
1st gen quinolones activity against?
GN
what is different about 2nd gen quinolones
have a fluorine sub. at C6 and a heterocyclic ring at C7
what is the most potent fluoroquinolone?
ciprofloxacin
2nd gen quinolones have activity against
More activity against GP and still GN coverage
3rd and 4th gen quinolones have activity against
more for GP than 1st and 2nd, still GN but not as much as ciprofloxacin
what quinolone is considered the “last resort” due to its toxicities
moxifloxacin
what gen is cipro
2nd
what gen is levofloxacin
3rd/4th? (he doesnt actually say i think)
used topically to treat impetigo
A. Ciprofloxacin
B. Levofloxacin
C. Moxifloxacin
D. Ozenoxacin
D
Ozenoxacin precaution
overgrowth with non-susceptible bacteria and fungi
general adverse effects for all quinolones (unique ones)
tendonitis, tendon rupture, peripheral neuropathy, CNS effects
quinolone MOA
inhibition of DNA religation in the topo II-DNA complex
UTIs
A. Ciprofloxacin
B. Levofloxacin
C. Moxifloxacin
D. Ozenoxacin
A
Prostatitis
A. Ciprofloxacin
B. Levofloxacin
C. Moxifloxacin
D. Ofloxacin
A and D
Shigellosis
A. Ciprofloxacin
B. Levofloxacin
C. Moxifloxacin
D. Ozenoxacin
A
diabetic foot infections
A. Ciprofloxacin
B. Levofloxacin
C. Moxifloxacin
D. Ozenoxacin
A
3 resistance mechs for fluoroquinolones
1) decreased cellular permeability
2) efflux pumps
3) mutation of target enzymes
T or F:
fluoroquinolones are readily absorbed orally
true
T or F:
all fluoroquinolones are widely distributed
true
major inactive metabolite of quinolones
glucuronide at 3-carboxyl position
why are fluoroquinolones not recommended for pts under 18?
they can damage growing cartilage and cause arthropathy
which random ass quinolone has been associated with hyperglycemia and hypoglycemia in diabetic patients
gatifloxacin
