Antibiotics - Clindamycin/Tetracycline/Chloramphenicol Flashcards
Clindamycin mechanism of action
50S inhibitor
similar to macrolides
Clindamycin clinical use
aerobic G+ (staph/strep) & anaerobic G- (Bacteroides/Fusobacterium)
Ex: S. Aureus bone infections; pen for lung abscesses; MRSA; IV for Toxo in AIDS
Clindamycin danger
C. diff
Clindamycin dosage
oral suspensions and IV (clindamycin phosphate) and topical
Clindamycin metabolism
P450s into 1) sulfoxidation 2) N-demthylation
metabolites inactive
Clindamycin pharmacokinetics
90% absorption orally; t1/2 = 1.5-5h; good CNS penetration (toxo)
Clindamycin adverse effects
diarrhea, C.diff, nasuea, vomiting, cramps, rash
If you get C.diff with clindamycin
switch to metro or vanco
Tetracycline history tidbit
in mummies from beer production
Tetracycline and metals
chelation with Ca/Al/Cu/Mg
Tetracycline administration route
still oral despite chelation
Tetracycline warnings
discolors developing teeth in kids
don’t inject w/o EDTA as it hurts when chelated w/ Ca2+
Tetracycline epimerization
forms epitetracycline (inactive) happens with old solutions and pH
Tetracycline dehydration
due to C-6 hydroxyl group
forms 4-epianhydrotetracycline (inactive and TOXIC)
Fanconi-like syndrome
Why are minocycline and doxycycline safer
do not form 4-epianhydrotetracycline so no risk of toxicity (Fanconi-like syndrome) - lack the C-6 OH group
90-100% oral F
Tetracycline mechanism of action
30S inhibitor; blocks A site attachment; do not overlap with macrolide binding
can block protein synthesis in host but no uptake mechanism
blocks in 6x different locations
Tetracycline therapeutic use
broad-spectrum
acne; chlamydia; rickettsia; brucellosis; spriochetes
anthrax/plague/tuleramia/Legionnaire’s
which tetracyclines absorption lowered 50% by food/milk
tetracycline/demeclocycline/oxytetracycline
which tetracyclines have no toxicity
minocycline and doxycycline
doxycycline from
oxytetracycline
minocycline from
demeclycycline
Best tetracycline half-life and how long
doxycline
18-22hr
