Reserve & Special Use AB - 10Qs Flashcards
Why are they called reserve AB?
Becuz of narrow spectrum and/or severe toxicities
List the reserve agents
A. Chloramphenicol B. Glycopeptides e.g. Vancomycin, Teicoplanin C. Linezolid (Zyvox) D. Streptograminss e.g. Quinopristin+Dalfopristin E. Cyclic Lipopeptides e.g. Daptomycin F. Cyclopeptides e.g. Bacitracin G. Novobiocin H. Mupirocin
What are the AEs of chloramphenicol?
A. Blood dyscrasias
B. Gray syndrome
MOA of chloramphenicol
BacterioSTATIC or BacteriCIDAL depending on m.o. and dose (UNIQUE)
Target of chloramphenicol
Binds to 50s ribosomal subunit and inh protein synthesis
What other drugs does chloramphenicol’s target overlap with?
Macrolides e.g. Erythromycin, Clarithromycin, Azithromycine Lincosamides e.g. Clindamycin, clindamycin phosphate,
Lincomycin
Is the antianabolic effect of chloramphenicol also seen in humans?
Yes
Name the m.o. Chloramphenicol is reserved for?
Gram tve
Anaerobes
How does resistance dev to chloramphenicol?
Stepwise and involves INDUCTION OF AN ENZYME that acetylates the drug
What’s chloramphenicol used primarily for?
Typhoid fever (Salmonella typhi)
H. Influenza meningitis
Uses of Chloramphenicol’s pro drugs
A. Hemisuccinate ester
B. palmitate ester
A. IV injection
B. oral suspension
MOA of Vancomycin
BacteriSTATIC
What’s vancomycin’s target?
Binding to acyl D-Ala-D-Ala peptides and so inh bacterial cell wall biosynthesis
Uses of vancomycin
Gram tve
Anaerobes
MRSA
Uses of PO vancomycin
C. Diff (colitis)
How does resistance dev against vanco?
Alteration of cell wall D-ala groups precursors to a lactate precipitate
T/4 vanco can’t recognize target
What’s the unique SE of vancomycin?
Red-man/ red-neck syndrome
How’s Teiocoplanin’s (similar to vanco) delivered to the body?
IM
As a depot (highly protein bound), t4 dosed once daily
Whats d Relationship btw Teicoplanin and histamine release?
Doesn’t cuz significant histamine release ff IV admin
T4, fewer SEs
Is Teicoplanin used over vanco?
No.
Becuz of cost. It’s reserved for when vanco is ineffective)
What’s linezolid’s target?
Binds to 23s ribosomal subunits of the 50s subunit
MOA of Linezolid.
BacteriCIDAL against Streptococci sp
BacterioSTATIC against other gram tve
What’s Linezolid clinically used for?
Inf caused by AEROBIC gram tv
What’s the recommended use for Linezolid?
For VRE - Vanco resistant enterococci
Staph aureus (including MRSA)
Streptococcus sp
How’s Linezolid metabolized?
By oxidative opening of the morpholine ring
Is drug-drug int cuzed by metabolism a concern for Linezolid?
No.
P-450 doesn’t metabolize Linezolid, so no d-d int
Does Linezolid affect MAO?
Yes.
Linezolid is a non-selective inh of MAO
What’s the relationship btw Macrolides and streptogramniss?
There’s a remote relationship, but little or no cross sensitivity.
Name the targets of streptogramniss (Quinopristin + Dalfopristin).
50s subunit
What’s the primary use of streptogramniss (Quinopristin + Dalfopristin)?
For VRE faecium, NOT VRE faecalis
What are the special cases that streptogramniss (Quinopristin + Dalfopristin) is used for?
Gram tve org e.g. S. aureus and Streptococci sp
Any significant metabolism for streptogramniss (Quinopristin + Dalfopristin)?
Potent inh of P-450 3A4
T4 d-d int is possible
What’s the target of Daptomycin?
Bacterial membranes causing rapid depolarization
What’s Daptomycin indicated for?
SSSI caused by a variety of gram tve org e.g.
E. faecalis
Staph aureus including MRSA
What parameter should be monitored if a pt is on Daptomycin?
CPK
Elevation of CPK has been reported => muscle pain/ weakness
What enhances the activity of Bacitracin?
Zn ion
How should bacitracin be stored?
Refrigerated and should not be kept for more than 1 week
MOA of bacitracin
BacteriSTATIC/CIDAL depending on m.o. and conc.
What’s the target of bacitracin?
Interferes with late stage cell wall formation and cell membrane
What’s bacitracin occasionally used to treat?
PMC
Following what route of admin is bacitracin well absorbed?
IM
Bacitracin is widely distributed into the tissues except in
CNS
MOA of Polymixin B sulfate
BacteriCIDAL after binding to phospholipids of CYTOPLASMIC MEMBRANE.
SEs of bacitracin
Severe nephro- & neurotoxicity
What’s the MOA of Novobiocin?
BacterioSTATIC by inh DNA gyrase
What’s Novobiocin reserved for?
For resistant gram tve m.o. - Staph aureus, Proteus vulgaris
What’s the effect of rapid hydrolysis in vivo in Mupirocin?
Used Topically only for Staph and Strept. skin inf
What’s Mupirocin’s target?
Binds to bacterial enzyme isoleucyl transfer-RNA synthase preventing the incorporation of isoleucine into bacterial proteins
Which AB is cidal against Strep and static against other gram tv m,o.?
Linezolid
Which AB causes an increase in CPK, therefore, muscle pain/weakness may be an issue?
Daptomycin
Which AB does Zn ion. Enhances its activity?
Bacitran
Which atypical / reserve AB are both bacteriSTATIC and CIDAL?
Chloramphenicol
Linezolid
Bacitracin
Which reserve AB are active against VRE?
Linezolid
Quinopristin+Dalfopristin [VRE faecium only]
What reserve AB are inh of P-450?
Quinopristin+Dalfopristin
Which atypical AB are effective against gram tve Anaerobes?
Chloramphenicol
Vancomycin
Which atypical AB is effective against gram tve Aerobes?
Linezolid
Which reserve AB attacks bacterial membrane?
Daptomycin
Bacitracin