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1
Q

Protein Synthesis Inhibitors MOA

A

tRNA 8 binds to acceptor site; tRNA 7 binds 7 AA to 8AA (transpeptidation); uncharged tRNA 7 released, and tRNA 8 transfers to peptidyl site (translocation);
Chloramphenicol and macrolides block transpeptidation and T blocks binding to the acceptor site on 30S ribosome

2
Q

Protein Synthesis Inhibitors

A
Erythromycin
Modified Macrolides/Azolides
Telithromycin
Cethromycin
Tetracyclines
Clindamycin
Linezolid
Nitrofurantoin
others
3
Q

Erythromycin MOA

A

Reversibily binds to 50S resulting in inhibition of translocation of tRNA, thus blockage of transpepidation reactions
Bacteriostatic
Gram + > gram -

4
Q

Erythromycin SOA Atypical pathogens

A
mycoplasma pneumoniae
chlamydia pneumoniae
chlamydia trachomatis
ureaplasma urealyticum
Does NOT cover MRSA
5
Q

Erythromycin clinical use

A

Chlamydial infections
URI/LRIs caused by strep pneumonia, mycoplasma and legionella in PCN allergy pts
strep pharyngitis in PCN allergy
Diptheria, Pertussis, cat-scratch fever (Bartonella)
Acne-topical
Oral prep for bowel surg

6
Q

Erythromycin

A

Bioavilability 35 +/- 25%
Best taken on empty stomach, take with food if n/v
Does NOT cross BBB, crosses placenta (cat B)
Primarily hepatic and biliary elimination

7
Q

Erythromycin ADEs

A
GI
hepatotoxicity: cholestatic jaundice
EES hepatotoxicity--hypersensitivty to ester
hypersensativity
Cardiotoxicity--prolonged QT
Ototoxicity
8
Q

Erythromycin drug interactions

A
Inhibition of CyP450 metabolism of other drugs
Theophylline
Carbamazepine
Warfarin
Cyclosporin
9
Q

Erythromycin Dosing

A

Erythromycin base, estolate or stearate 250 mg - 500 mg qid
EES: 400-800mg q6-12 hrs
IV: 500mg qid, up to 4gm for severe infections

10
Q

Modified Macrolides/Azolides

A

Developed to overcome limitations of erythromycin

11
Q

Modified macrolides/Azolides drugs

A

Clarithromycin (Biaxin) (PO)
Azithromycin (Zithromax) (PO and IV) (Improved resistance to acid degradation, improved tissue penetration) - azolide

Troleandomycin (TAO) – orphan drug

12
Q

Azithromycin SOA

A

Gram +, slighly less than erythro for staph
Gram -, slighly better for h. flu than erythro
Highly active against chlamydia

All macrolides/azolides: **Active against mycobacterium avium intracellulare complex

13
Q

Clarithromycin clinical use

A

treat h. pylori (with amox + omperazole)

14
Q

Azithromycin clinical use

A

STD (chlamydia, chancroid, NGU, PID)

15
Q

Both clarithromyicn and azithromycin use

A

Upper and lower respiratory tract infections, community acquired pneumonia, alternative to cephalosporin or Augmentin for sinusitis, otitis media; skin and skin structure infections;
Treatment of Mycobacterium Avium Complex

16
Q

Azithromycin Pharmacokinetics

A
best taken 1 hr before/2 hrs after meals, but with meals okay
High tissue level distribution
large Vd
Preg Cat B
Hepatic metabolism, biliary elimination
t1/2=68hrs
17
Q

Clarithromycin Pharmacokinetics

A

55-68% absorption, no effect or slightly increased with food
high tissue level distribution
Preg Cat C
hepatic metabolism with active metabolite (some renal clearance 18%)
t1/2=3.5-5 hours
Adjust dose in renal insufficiency (CrCl <30ml/min)

18
Q

Modified macrolides/azolides ADEs

A
GI (less than erythro)
metallic taste
ototoxicity in high dose, long term use
hypersensativity (<1%)
hepatotoxicity (rare)
19
Q

Macrolides/azolides drug interactions

A

similar to erythro.
azithromycin has MANY fewer; case reports with HMG-CoA RI and warfarin
Digoxin–clarith and erythro

20
Q

Azithromycin dose

A

(Zithromax) generic (Susp, tablets, IV):
500mg x1, then 250mg qd x4days (Z-pak)
1gm PO x1 for Chlamydia cervicitis, urethritis
MAC: 600mg daily

21
Q

Clarithromycin dose

A

(Biaxin) tablets, susp: 250 – 500mg bid (renal insufficiency: 500mg x1, then 250mg bid); ER tablets: 2 x 500mg qd; suspension tastes nasty

22
Q

Telithromycin

A
Active against strep pneumonia, including multi drug resistant
h. flu
moracella catarhalis
chlamydia pneumonia
mycloplasma pneumonia
USE: mild to moderate CAP
23
Q

Cethromycin

A

new ketolide with activity against CA-MRSA; studied for CAP–possible approval
FDA found safe but not effective

24
Q

Tetracyclines drugs available

A

Short acting: tetracycline
intermediate: demeclocycline (used to treat SIADH)
long-acting: doxycyclcine, minocycline, tigecycline–used most often

25
Q

Tetracyclines MOA

A

enter cell via passive diffusion or active transport, reversibly bind to 30S, prevent binding of tRNA and protein synthesis
bacteriostatic

26
Q

Tetracycline resistance

A

widely used in animal feeds

decreased intracellular concentration d/t decrease in influx or increased efflux by active transport.

27
Q

Tetracyclines SOA

A

gram + aerobes–bacillus anthracus, listeria monocytogenes, s. aures
gram - aerobes- h flu, m. catarrhalis, pasturella mluocida, bartonella, vibrio
gram + anaerobes- strep
gram 0 anaerobes: fuscobacterium
others: chlmydia, mycoplasma pneu., borrelia, ricettsial, h. pylori, treponema pallidum

28
Q

tetracyclines clinical use

A
CAP: s. pneumonia, chlamydia, mycoplasma--doxycycline
Rickettsia
Alt for syphillis, lyme disease
h. pylori
uncomme gram neg
ace--propionibacterium acnes
demecloclycline: SIADH
29
Q

Tigecycline

A

glycylcycline–tetracycline-like antibiotic
indications: skin infect00e.coli, e. faecalis, s. aurus (MRSA), strep, bacteroides frgailis
complicated abdominal infections

30
Q

tetracyclines pharmacokinetics

A

tetra- 60-80% absorbed, impaired by good
doxy, minocyc- 90-100%
Tigecycline–NO PO absorption, IM poor, erratic absorption
Distribution: Wide, including CNS
Crosses placena: Preg Cat C
Elimination: primarily hepatic, some renal, doxy and tige don’t need to adjust dose for renal

31
Q

Tetracyclines ADRs

A

GI
Esophagitis (don’t take right before lying down)
Photosensitivity
Teeth/bone–tetra deposited in calicfying areas
Vestibular
Renal effects

32
Q

Tigecycline

A
bacteriostatic
ADRs: n/v/d, photosensitivity
Drug interactions: inhibits warfarin 
Dose: 100mg IV follow by 50mg IV q12h
used for resistant organisms
33
Q

Tetracycline drug interactions

A

Divalent/trivalent cations (esp tetra!)
doxycycline: carbamazepine, phenytoin, barbiturates, chronic alcohol shorten half life
wafarin: alteration of gut flora
digoxin
anti-infective agents: TCN and PCN (static vs cidal)

34
Q

Tetracycline dose

A

250-500mg q6h PO

35
Q

Doxycycline Dose

A

100mg qd or bid

36
Q

Minocycline Dose

A

PO, IV 100 mg bid

37
Q

Clindamycin SOA

A

Gram + aerobes, anaerobes NOT C. diff
Gram - anaerobes bacteroids, fusobacterium
Pneumocystis carinii
toxoplasma gondii

38
Q

Clindamycin clinical uses

A

Bacteroides infections
Penetrating abdominal wounds
BV
Skin infections
dental/oral infections
endocarditis prophylaxis in pts allergic to PCN
AIDS: PCP (with primaquine) toxoplasmosis

39
Q

Clindamycin pkin

A

absorption: well absorbed from GI, 70% bioavailabily
distribution: widely, 90% protein bound
Minimal BBB crossing
Preg cat B
Elimination: metabolized in liver, excreted in bile
1/2 life 2-4 hours, need to dose 3-4 x / day

40
Q

Clindamycin ADRs

A

Diarrhea, mild, self-limited (make sure not c. diff overgrowth diarrhea!)
esophageal irritation–don’t lie down for 1 hr
local
hepatotoxicity
hypersensitivity–rashes, fever

41
Q

Clindamycin dosing

A

150-450 mg q6h PO

42
Q

Chloramphenicol

A

gram + aerobes strep and staph
gram - aerobes h. flu, neisseria, bordetella, salmonella, shigella
gram + anaerobes-c. perfringes, corynebacterium diptheriaea, peptococcus
gram - anaerobes: bacteroides, fusobacteria
rickettsial spp

43
Q

Chloramphenicol clinical uses

A

serious infections unresponseive to other antibiotics
rickettsia infections
alt for salmonella
severe infections–high pcn resistant strep pneu, meningococcus with PCN allergy–crossess BBB even w/o inflammaed meninges
topical: eye

44
Q

Chloramphenicol ADRs

A

(important)
Hematologic–dose-related, reversible bone marrow suppresion
Aplastic anemia
Gray baby syndrome: circulatory collapse
Optic neuritis –> blindness
GI, hepatitis, n/v/d unpleasant taste, glossitis
drug interactions: inhibits hepatic enzymes, warprin, phenytoin

45
Q

Quinupristin/Dalfopristin SOA

A

Resistance with VRE
SOA: bacterostatic againsts E. faecium and cidal against staph (MRSA, MSSA) and PCN-resistant
s. pneu. legionella pneu, listeria mono.

46
Q

Quinupristin/Dalfopristin clinical use

A

tx of life-threatening infections associates with VRE bacteremia
complicated skin infect by s. aureus and strep pyogenes

47
Q

Quinupristin/Dalfopristin pkin

A

administered IV only q8-12 hrs

mainly fecal elimination, some urinary

48
Q

Quinupristin/Dalfopristin ADRs

A

Venous irritation
Skin rash
myalgias, arthralgias significant
VERYY EXPENSIVE

49
Q

Linezolid

A

oxazolidinone; new class of abx
primarily bacterostatic–inhibits protein synthesis
binds with 23 S ribosome (no cross resistance)
Unique MOA
Totally synthetic drug, resistance reported within months of marketing

50
Q

Linezolid clinical use

A

tx of serious infections caused by VRE
effective for MRSA and infections caused by high-level PCN reistant s. pneu
less effective than vancomycin for MRSA endocarditis

51
Q

Linezolid ADRs

A

Myelosuppresion, reversible thrombocytopenia with prolonged therapy
GI
headache
$$$$$$$
Many drug interactions (I-MAOs, foods with tyramine (severe HTN), SSRI)

52
Q

Nitrofurantoin

A

Macrodantin or Macrobid
MOA: urinary antiseptic
SOA: many gram + and -, NOT p. aeruginosa and proteus

53
Q

Nitrofurantoin clinical Use

A

UTI (acute cystitis, not pyelo)

54
Q

Nitrofurantoin dose

A
absorption better with meals. 
50-100mg PO 4x/d for 7 days
Macrobid: 100 mg BID 
UTI prophylaxis: 50-100mg PO at bedtime
do not use if CrCl is less than 60mL/min
55
Q

Nitrofurantoin ADRs

A

GI
Hematologic: hemolytic anemia. avoid in G-6-PD definiciency and infants <1mo
Hepatic: cholestatic jaundice syndrome, hepatic necrosis, hepatitis
immunologic: hypersensitivity, pulmonary fibrosis
peripheral neuropathy