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Pharm Exam V > Antibiotics III - inhibitors of protein synthesis > Flashcards

Antibiotics III - inhibitors of protein synthesis Flashcards

1
Q

Inhibitors of 30s translation:

Classes/drugs?

A

Inhibitors of 30s translation:

a. Aminoglycosides: Amikacin, Gentimycin, and Tobramycyin
b. Aminocylitol: spectinomycin

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2
Q

Aminoglycosides MOA?

Aminocylitol/spectinomycin MOA?

A

Aminoglycoside MOA: entry into cell through porins with oxygen and energy (thus doesnt work for anaerobes) –> binds to 16s rRNA of the 30s subunit –> inhibits translocation of peptidyl tRNA from the A site to the P site thus blocking translation initiation; also causes miscoded proteins. BACTERIOCIDAL

Spectinomycin MOA: also binds 16s rRNA but at a different site; BACTERIOSTATIC

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3
Q

Aminoglycoside/Aminocyclitol:

Spectrum?

A

Aminoglycoside/Aminocyclitol:

Spectrum: - Narrow TI due to toxicity, not active against any anaerobes and many G+

a. G- aerobes: for serious infections (use aminoglycosides), only some G+ aerobes
b. N. gonorrhoeae - Spectinomycin (if b-lactam/quinolone allergy or resistance to cephalosporins)
c. Topical/ophthalmic forms for burns, wounds, ulcers. Contraindicated: mild/moderate infections. ONLY SEVERE.

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4
Q

Aminoglycoside/Aminocyclitol:

Excretion? Differences among individuals?

A

Aminoglycoside/Aminocyclitol:

Renal but highly variable excretion

Neonates/elderly excrete slower

CF/burn patients excrete faster

**Between single route of excretion, extreme individual variability, and dose dependent toxicity –> must use care with administration. Check drug levels**

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5
Q

Aminoglycoside/Aminocyclitol:

Interactions?

A

Aminoglycoside/Aminocyclitol:

Interactions:

a. B-lactams are inactivated by aminoglycosides in solution; BUT potentiate in vivo by increasing aminoglycoside entry into cell
b. Nephrotoxic drugs (esp. cephalosporins)
c. Ototoxic drugs (esp. loop diuretics and cisplatin)
d. Neuromusclar blockade agents

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6
Q

Aminoglycoside/Aminocyclitol:

Adverse events?

A

Aminoglycoside/Aminocyclitol:

Adverse events:

a. Ototoxiciy: dose dependent, vestibular (change in balance), auditory (loss of high range first), and auditory damage to fetus during pregnancy
b. Renal toxicity - dose dependent
c. Neuromuscular block: esp. with myasthenia gravis and at high concentration.

Most releated AE due to DOSING ISSUES

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7
Q

Tetracyclines?

MOA? Selectivity?

A

Tetracyclines: doxycycline and tetracycline

MOA: binds 16s of rRNA 30s –> blocks binding of aminoacyl tRNA to mRNA ribosome complex –> prevents addition of more amino acids to the growing peptide chain. Bacteriostatic

HIGHLY selective to accumulate bacteria and not mammals (we dont have the transport system to get them past the inner cyto. membrane)

Minimal differences in efficacy between tetracyclines

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8
Q

Tetracyclines:

Spectrum?

A

Tetracyclines Spectrum: used to be broad – overuse (resistance)

Active against many G-/+: Cornybacterium acnes, H. flu, Proprionibacterium acnes (acne), Rickettsia (typus, rocky mountain spotted fever: Doxycycline), B. anthracis (prophylaxis and treatment), Chlamydia, Vibrio cholerae (Doxycycline), Mycoplasma pneumoniae, and Boriella; Spirochetes (Lyme, syphilis): Doxycycline. Also for some protozoal infections and malarial prophylaxis (Doxycycline). DOC: tick borne diseases

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9
Q

Tetracyclines:

  1. Contraindications?
  2. Difference between doxycycline and tetracycline kinetics?
A

Tetracyclines:

  1. Contra: kids <8 and pregnant/lactating; these convert to toxic forms over time (cause severe kidney damage): watch expiration date and dispose of unused meds!
  2. Kinetics: Doxycyline: lipid soluble, hepatic/fecal excretion - unaffected by renal function. Tetracycline: not lipid soluble, renal excretion; Affected by renal function
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10
Q

Tetracyclines:

Interactions?

A

Tetracyclines:

Interactions:

Doxycycline: Normal meal - little effect and milk and dairy still have ok levels

Tetracycline: Normal meal and milk/diary: lowered

Both: lowered therapeutic levels with antacids, NaHCO3, and iron salts

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11
Q

Tetracyclines:

Adverse effects?

A

Tetracyclines: Adverse:

a. GI distress
b. Photosensitivity (esp Doxycycline)
c. Hepatotoxicity (dose related: more likely with pregnancy and renal impairment)
d. Nephrotoxicity
e. Super infections (from chane of normal flora bacteria: C. difficile: colitis)
f. Skeletal (not for kids bc it binds bones and teeth)
g. Pregnancy

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12
Q

Tetracyclines:

Resistance?

A

Tetracyclines:

Resistance:

a. Most common: plasmid encoded efflux pumps
b. Production of proteins that interfere with binding to ribosome
c. Enzymatic inactivation of Tetracyclines

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13
Q

Glycylcycline:

Drug?

  1. MOA?
  2. Spectrum?
A

Glycylcycline:

Tigecycline

  1. MOA: targets 30s at a novel site; similar structure to tetracyclines but 5x higher affinity; NOT expelled by efflux pumps. Bacteriostatic
  2. Spectrum: Broad: serious skin/ab infections; G+ (including MRSA), G-, anaerobes, NOT effective against pseudomonas or proteus
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14
Q

Glycylcycline: Tigecycline

  1. Adverse effects?
  2. Contraindications?
A

Glycylcycline: Tigecycline

  1. Adverse: same as tetracyclines (gi, photosensitivity, hepatotox, nephrotox, super infections, skeletal, and pregnancy issues)
  2. Contraindications: kids and pregnancy
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15
Q

Inhibitors of 50s translation:

Drug classes/drugs?

A

Inhibitors of 50s translation:

a. Macrolides: Azithromycin, clarithromycin, and erythromycin
b. Ketolide: Telithromycin
c. Streptogramins: Dalfopristin/Quinopristin
d. Oxazdidinone: Linezolid

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16
Q

Macrolides/Ketolide:

  1. MOA?
  2. General spectrum?
A

Macrolides/Ketolide:

  1. MOA: inhibits translocation by binding reversibly to 23s of 50s ribosomal subunit and blocks exit channel where the peptid emerges. Bacteriostatic
  2. Spectrum:

G+: Strep especially pulmonary infections

G-: T. pallidum, mycoplasma, and boriella

17
Q

Macrolides/Ketolide:

  1. Azithromycin spectrum?
  2. Clarithromycin spectrum?
A

Macrolides/Ketolide:

  1. Azithromycin: particularly well for legionella pneumoniae, H. flu pneumonia, chlamydia, nisseria, bronchitis, and mycoplasma pneumonia
  2. Clarithromycin: bronchitis and m. avium complex seen in AIDs/immunosuppressed
18
Q

Macrolides/Ketolide:

  1. Erythromycin spectrum?
  2. Telithromycin specrum?
  3. Macrolide spectrum?
A

Macrolides/Ketolide:

  1. Erythromycin: bronchitis, otitis media, and m. pneumoniae
  2. Telithromycin: pneumonia (especially CAP)
  3. Macrolides: conebacterium acnes (acne vulgaris), t. pallidum (syphilis), and Lyme disease
19
Q

Macrolides/Ketolide:

  1. Erythromycin/Azithromycin: dosing schedule?
  2. Distribution of Azithromycin?
  3. Elimination?
A

Macrolides/Ketolide:

  1. Erythro/Azithromycin: food inhibits absorption so give 1 hour before or 2 hours after a meal
  2. Azithromycin: excellent distribution to the lungs
  3. Elimination: not for liver damage due to biliary excretion; Clarithromycin: 30% renal excretion - adjust dose in renal failure patients
20
Q

Macrolides/Ketolide:

Drugs with a role via metabolism?

A

Macrolides/Ketolide:

Clarith/Erythromycin: liver metabolism CYP3A4 - cause many drug interactions with:

a. carbamazepine/valproate (AEDs)
b. Corticosteroids
c. Digoxin
d. Theophylline (asthma)
e. Warfarin

21
Q

Macrolides/Ketolide:

  1. Azithromycin interactions?
  2. Erythromycin interactions?
  3. Clarithromycin interactions?
  4. All macrolide interactions?
A

Macrolides/Ketolide:

  1. Azithromycin: antacids w/ Mg/Al: decrease serum peak
  2. Erythromycin: antihistamines/fluoroquinolones –> increase risk of arrhythmia; digoxin: increases concentration of drug; theophylline/anticoag: increase [serum] of drug
  3. Clarithromycin: theophylline/anticoag: increase [serum] of drug; Rifabutin/Rifampin: decreases serum [clarithromycin]
  4. All macrolides: chloramphenicol/clindamycin: antaxonizes abx effect of macrolides
22
Q

Macrolides/Ketolide:

Adverse effects?

A

Macrolides/Ketolide: Adverse effects:

a. GI: cramps, N/V/D Eryth: stimulation of GI motility Clarith: lower frequency of GI distress
b. Liver: cholestatic jaundice (due to thickened bile/plugs): Erythromycin and telithromycin
c. Cardiotox: arrhythmia: dont give w/ drugs that increase QT interval (Erythromycin)
d. Allergy: uncommon: fever, rash, and eosinophila
e. Visual toxicity: telithromycin

23
Q

Macrolides/Ketolide:

Resistance?

A

Macrolides/Ketolide:

Resistance: common in strep pneumoniae, staph aureus, H. flu, and M. avium

a. Primarily by changing drug target to decrease binding
b. Increase efflux
c. Macrolide hydrolysis by bacterial esterases
d. Mutant 50s ribosomal protein

24
Q

Amphenicol:

Drug?

MOA?

A

Amphenicol:

Chloramphenicol

MOA: binds 23s rRNA of 50s, blocks peptide formation, strongly affects mitochondrial protein synthesis. Bacteriostatic

25
Q

Amphenicol/Chloramphenicol:

Spectrum?

A

Amphenicol/Chloramphenicol: Spectrum:

a. Broad. G+/-. Aerobic and anaerobic
b. CNS when other treatments fail: Brain abscesses: B. fragilis and Strep. Meningitis: H. flu, strep pneumoniae, and N. meningitidis
c. Rickettsia and chlamydia when safer drugs not available
d. Topical: conjunctivitis

Available PO, IV, and topical

26
Q

Amphenicol/Chloramphenicol:

Interactions?

A

Amphenicol/Chloramphenicol:

Interactions:

a. Inhibits cyp450 and interacts with many other drugs
b. Erythromycin and clindamycin antagonist
c. Potentiates other drugs that cause BM depression

27
Q

Amphenicol/Chloramphenicol:

Adverse effects?

A

Amphenicol/Chloramphenicol:

Adverse effects: serious - thus use of this drug is limited:

a. BM suppression: reversible, dose-related. Aplastic anemia and other blood dyscrasias - not dose related, risk increases with more courses
b. Gray baby syndrome: acute, dose related. Newborns born w/o liver enzymes to metabolize –> CV collapse due to OD
c. Peripheral/optic neuritis: increased risk with long term therapy

28
Q

Amphenicol/Chloramphenicol:

Resistance?

Contraindications?

A

Amphenicol/Chloramphenicol:

Resistance: decreased membrane permeability, plasmid encoded acetyltransferase –> inhibits binding of drug to ribosome, and mutation of 50s

Contraindications: pregnancy (unless topical use) and moderate infection where safer drugs could be used

29
Q

Lincosamide:

Drug?

MOA?

A

Lincosamide:

Clindamycin

MOA: binds 50s and blocks peptide bond formation, blocks translocation/protein synthesis. Passively enters bacteria and concentrates in the mitochondria. Bacteriostatic

30
Q

Lincosamide/Clindamycin:

Spectrum?

A

Lincosamide/Clindamycin: Spectrum:

a. Serious anaerobic, some GPC (NOT enterococci), GNR, including those caused by B. fragilis and fusobacterium
b. Serious aerobic GPC infections if PCN resistant/allergy (Staph, strep, pneumo)
c. Pneumocystitis pneumonia (fungal) with primaquine
d. Toxoplasma in combo with pyrimethamine
e. Plasmodium in combo with chloroquine
f. Topical for acne

31
Q

Lincosamide/Clindamycin:

Interactions?

Adverse effects?

Contraindications?

A

Lincosamide/Clindamycin:

Interactions: potentiates neuromuscular blockers; antagonists of chloramphenicol and macrolides (similar binding)

Adverse effects: diarrhea, pesudomembranous colitis by C. diff (use metronidazole). *associated with extremely high risk of C. Diff related disease

Contraindication: severe hepatic impairment

32
Q

Lincosamide/Clindamycin:

Resistance?

A

Lincosamide/Clindamycin:

Resistance:

a. C. Difficile is naturally resistant**
b. 30% resistance in B. fragilis - Due to plasmid erm gene, can use D-test to determine ( disk diffusion test with erythromycin and clindamycin)

33
Q

Streptogramins:

Drugs?

MOA?

A

Streptogramins:

Dalfopristin/Quinopristin

MOA: mixture is synergistic. Binds 23s rRNA of 50s and blocks emergence of peptides from ribosomes (like macrolides) and also blocks translocation. Bactericidal except Bacteriostatic for strep faecium

34
Q

Streptogramins:Dalfoprisin/Quinoprisin:

Spectrum?

A

Streptogramins:Dalfoprisin/Quinoprisin:

Spectrum: Serious infections by GPC

a. VRSP/VRSA (vancomycin resistant strep pyogenes/staph aureus)
b. Complicated skin infection from MSSA or Staph epidermidis
c. Drug resistant strep pneumoniae

35
Q

Streptogramins:Dalfoprisin/Quinoprisin:

Interactions?

Adverse effects?

Contraindications?

A

Streptogramins:Dalfoprisin/Quinoprisin:

Interactions inhibits CYP3A4 and increases toxicity of other CYP3A4 substrates (antihistamines/macrolides); SSRI: risk of serotonin syndrome

AE: most common = phlebitis, increase in liver enzymes, arthralgia, and myalgia

Contraindication: liver failure and SSRI

36
Q

Streptogramins:Dalfoprisin/Quinoprisin:

Resistance?

A

Streptogramins:Dalfoprisin/Quinoprisin:

Resistance via ribosomyl conformational mutations:

a. Increased efflux
b. Acetyltransferase and hydrolase inactivation

37
Q

Oxazdidinone:

Drug?

MOA?

A

Oxazdidinone:

Linezolid

MOA: 50s, unsure; Bacteriostatic: for enterococci and staph

Bacteriocidal for strep

38
Q

Oxazdidinone/Linezolid:

Spectrum?

A

Oxazdidinone/Linezolid:

Spectrum:

a. G+: MRSA, PCN resistant strep, VRE (vancomycin resistant enterococcus) and VRSA
b. Drug resistant skin infections, nosocomial pneumonia
c. Poor against G- and anaerobes

39
Q

Oxazdidinone/Linezolid:

Adverse events?

Interactions?

Resistance?

A

Oxazdidinone/Linezolid:

AE: GI, HA, rash, myelosuppression, neurotoxicity, thrombocytopenia, mitochondrial toxicity (lactic acidosis and peripheral neuropathy)

Interactions: Linezolid = weak MAOI; additive with MAOI antidepressand and avoid tyramine rich food or risk hypertension

Resistance: rare; efflux pump and point mutations of 23s

Pharm Exam V (6 decks)

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