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Protein Synthesis Inhibitors Flashcards

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

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2
Q

Protein Synthesis Inhibitors

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

Erythromycin MOA

A

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

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4
Q

Erythromycin SOA Atypical pathogens

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

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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

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7
Q

Erythromycin ADEs

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

Erythromycin drug interactions

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

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10
Q

Modified Macrolides/Azolides

A

Developed to overcome limitations of erythromycin

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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

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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

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13
Q

Clarithromycin clinical use

A

treat h. pylori (with amox + omperazole)

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14
Q

Azithromycin clinical use

A

STD (chlamydia, chancroid, NGU, PID)

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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

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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
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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)

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18
Q

Modified macrolides/azolides ADEs

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

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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

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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

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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
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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
Tetracyclines MOA
enter cell via passive diffusion or active transport, reversibly bind to 30S, prevent binding of tRNA and protein synthesis bacteriostatic
26
Tetracycline resistance
widely used in animal feeds | decreased intracellular concentration d/t decrease in influx or increased efflux by active transport.
27
Tetracyclines SOA
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
tetracyclines clinical use
``` CAP: s. pneumonia, chlamydia, mycoplasma--doxycycline Rickettsia Alt for syphillis, lyme disease h. pylori uncomme gram neg ace--propionibacterium acnes demecloclycline: SIADH ```
29
Tigecycline
glycylcycline--tetracycline-like antibiotic indications: skin infect00e.coli, e. faecalis, s. aurus (MRSA), strep, bacteroides frgailis complicated abdominal infections
30
tetracyclines pharmacokinetics
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
Tetracyclines ADRs
GI Esophagitis (don't take right before lying down) Photosensitivity Teeth/bone--tetra deposited in calicfying areas Vestibular Renal effects
32
Tigecycline
``` bacteriostatic ADRs: n/v/d, photosensitivity Drug interactions: inhibits warfarin Dose: 100mg IV follow by 50mg IV q12h used for resistant organisms ```
33
Tetracycline drug interactions
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
Tetracycline dose
250-500mg q6h PO
35
Doxycycline Dose
100mg qd or bid
36
Minocycline Dose
PO, IV 100 mg bid
37
Clindamycin SOA
Gram + aerobes, anaerobes **NOT C. diff** Gram - anaerobes bacteroids, fusobacterium Pneumocystis carinii toxoplasma gondii
38
Clindamycin clinical uses
Bacteroides infections Penetrating abdominal wounds BV Skin infections dental/oral infections endocarditis prophylaxis in pts allergic to PCN AIDS: PCP (with primaquine) toxoplasmosis
39
Clindamycin pkin
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
Clindamycin ADRs
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
Clindamycin dosing
150-450 mg q6h PO
42
Chloramphenicol
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
Chloramphenicol clinical uses
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
Chloramphenicol ADRs
(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
Quinupristin/Dalfopristin SOA
Resistance with VRE SOA: bacterostatic againsts E. faecium and cidal against staph (MRSA, MSSA) and PCN-resistant s. pneu. legionella pneu, listeria mono.
46
Quinupristin/Dalfopristin clinical use
tx of life-threatening infections associates with VRE bacteremia complicated skin infect by s. aureus and strep pyogenes
47
Quinupristin/Dalfopristin pkin
administered IV only q8-12 hrs | mainly fecal elimination, some urinary
48
Quinupristin/Dalfopristin ADRs
Venous irritation Skin rash myalgias, arthralgias significant VERYY EXPENSIVE
49
Linezolid
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
Linezolid clinical use
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
Linezolid ADRs
Myelosuppresion, reversible thrombocytopenia with prolonged therapy GI headache $$$$$$$ Many drug interactions (I-MAOs, foods with tyramine (severe HTN), SSRI)
52
Nitrofurantoin
Macrodantin or Macrobid MOA: urinary antiseptic SOA: many gram + and -, NOT p. aeruginosa and proteus
53
Nitrofurantoin clinical Use
UTI (acute cystitis, not pyelo)
54
Nitrofurantoin dose
``` 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
Nitrofurantoin ADRs
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

Module II (4 decks)

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