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y2 pharmaco > Tetracyclines & Aminoglycosides > Flashcards

Tetracyclines & Aminoglycosides Flashcards

1
Q

Name the 3 Tetracyclines

A
  1. Tetracycline
  2. Doxycycline
  3. Minocycline
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2
Q

What do Tetracyclines cover/effective against?

A

Broad spectrum (gram pos & negs) & some atypical bacteria

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3
Q

What are the 3 atypical bacteria?

A
  1. Mycoplasma
  2. Legionella
  3. Chlamydia
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4
Q

Diff between bacteriocidal and bacteriostatic

A

Bacteriocidal - kills bacteria
Bacteriostatic - arrests bacteria (only)

E.g. aminoglycosides are bacteriocidal unlike tetracyclines that are bacteriostatic

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5
Q

Name the 3 categories of protein synthesis inhibitors (30S)

A
  1. Tetracyclines
  2. Glycylcycline
  3. Aminoglycosides
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6
Q

Administration of Tetracyclines.

A

Good oral bio-availability => mostly oral admininstration

  • can actl be administered IV but unnecessary lah
  • mostly manufacture in oral forms too
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7
Q

Tetracyclines are similar to Fluoroquinolones in what sense..

A

Cannot be taken w dairy pdts, such as milk

  • or other substances that contain divalent & trivalent cations
  • e.g. Mg or Al antacids or Fe supplements
  • forms non absorbable chelates that decreases absorption
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8
Q

Tetracyclines have inadequate activity against..

A
  1. Pseudomonas aeruginosa
  2. Proteus
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9
Q

Can Tetracyclines be used during pregnancy?

A

big no.
- category D in pregnancy

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10
Q

Which Tetracycline is best for CNS treatment?

A

Doxycycline

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11
Q

Tetracycline (specifically) are eliminated and cleared via..

A

Renal elimination, excreted by kidney

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12
Q

Which tetracycline is effective against MRSAs?

A

Doxycycline

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13
Q

Which Tetracycline is metabolised by the liver before excretion?

A

Minocycline
- thus, tigecycline aslo eliminated via biliary/fecal route
- dose reduction reccomended in pxs w severe hepatic dysfunction

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14
Q

What are Glycylcyclines?

A
  • new class of AB derived from tetracyclines
  • structurally related to minocycline, but altered to 1. Larger spectrum of activity 2. Decreased susceptibility to development of bacterial resistance
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15
Q

Name the only glycylcycline approved for antibiotic use.

A

Tigecycline

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16
Q

What are the 2 common mechanisms of tetracycline resistance?

A
  1. Ribosomal protection
    - bugs produce proteins to prevent AB from binding to ribosomal subunit/displace AB from subunit
  2. Resistance mediated by acquired efflux pumps
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17
Q

How does Tigecycline work against Tetracycline resistant bacteria?

A
  1. Tigecycline modified to have higher affinity to the ribosomal subunit => doesnt get displaced by the proteins
  2. Tigecycline modified to not be a substrate for the bacterial efflux pumps
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18
Q

How is Tigecycline administered?

A

Only parentally
- aka IV
- poor oral bioavailability

19
Q

Can Tigecycline be given during pregnancy?

A

No. Cat D

20
Q

Elimination & clearance of Tigecycline?

A

Biliary elimination, Fecal excretion

  • thus, no dosage adjustments needed for pxs w renal impairment
  • dose reduction reccommended in severe hepatic dysfunction
21
Q

Tigecycline is not active against..

A
  1. Pseudomonas species
  2. Proteus
22
Q

Can Tigecycline be used against MRSA?

A

Yes.

23
Q

Can Tigecycline be used against ESBLs?

A

Yes.
- can be used against extended-spectrum β-lactamase producing gram neg bacteria
- useful against carbapenem resistant strains

24
Q

Can Tigecycline be used against Vancomycin-resistant enterococci (VRE)?

A

Yes.

25
Q

List the indications for/coverage of Tigecycline.

A
  1. MRSA (staphylococci)
  2. Multidrug-resistant streptococci
  3. Vancomycin-resistant enterococci(VRE)
  4. ESBL + carbapenem resistant strains
  5. Community acquired pneumonia
26
Q

Briefly list the adverse effects of Tetracyclines & Tigecycline.

A
  1. Gastric discomfort (oesophageal irritation & ulceration)
  2. Effects on calcified tissues (staining of teeth, hypoplasia of teeth)
  3. Phototoxicity
  4. Superinfections e.g. CDAD, thrush
  5. Hepatotoxicity
  6. Vestibular dysfunction
  7. Renal (accumulation of tetracycline in px w pres-existing renal disease)
27
Q

What the effects of Tetracyclines & Tigecycline on the GIT? + how shd the px be advised?

A

Gastric discomfort - esophageal irritation common

  • drug shd be eaten on empty stomach
  • drink plenty of water to reduce esophageal ulceration
  • do not lie down aft intake of drug
28
Q

Patients on Tetracycline & Tigecycline are at risk of CDAD, why?

A

Tetracycline & Tigecycline are broad-spectrum ABs
=> prolonged use may cause superinfections as they wipe out all bacteria
=> e.g. thrush, CDAD, etc (fungal & bacterial superinfections)

29
Q

Use of Tetracycline & Tigecycline may cause _______toxicity & _______toxicity.

A

Phototoxicity & Hepatotoxicity.

  • advise px to wear sunscreen and protective eyewear
  • to protect against severe sunburn
30
Q

List the contraindications of Tetracyclines & Tigecycline.

A

Not to be used in:
1. pregnant/breast-feeding women or in children less than 8 yrs of age
2. Last half of pregnancy => affects primary teeth
3. Children up to 7/8 yrs => can affect perm teeth (yellow-gray-brown discolouration)

31
Q

What are the 6 NOs for Aminoglycosides.

A
  1. No protein synthesis (inhibition @ 30S ribosomal subunit)
  2. Mainly aerobic Negative Organisms (spectrum)
  3. No during pregnancy
  4. No oral administration
  5. No CSF penetration
  6. Nephro & Oto toxicitiy
32
Q

How are Aminoglycosides cleared and excreted

A

Renal clearance, excreted thru urine
- will need dose adjustment in pxs w renal impairment

33
Q

What does Aminoglycosides not cover?

A

Anaerobes.
- req oxygen for active transport across inner membrane

34
Q

List the 5 Aminoglycoside drugs.

A
  1. Gentamicin
  2. Streptomycin
  3. Tobramycin
  4. Amikacin
  5. Neomycin
35
Q

Aminoglycosides cannot be used in anaerobes, why?

A
  1. Aminoglycosides need/are transported across inner membrane via active transport
  2. Energy-dependent phase => requires oxygen for pdn of energy
  3. Cannot occur under anaerobic conditions.
36
Q

Aminoglycosides are frequently used for __________ therapy for serious infections.

A

Empiric therapy.
- dk what the bug is, prescription of broad spectrum AB is solely calculated decision of observed symptoms
- while on empiric therapy, identification of bug occurs
- once bug is identified, step down & give targeted therapy

37
Q

Aminoglycosides are primarily effective against..

A

aerobic gram neg bacteria & mycobacteria

  • acts synergistically with beta lactams against gram pos bacteria
38
Q

Briefly list the 5 adverse effects of aminoglycosides.

A
  1. Ototoxicity - deafness in ear
  2. Nephrotoxicity - retention of drug in kidneys
  3. Neuromuscular paralysis - note in pxs w myasthenia gravis
  4. Hypersensitivity rxns (skin rash)
  5. Contraindicated in pregnancy, Cat D
39
Q

Administration of Aminoglycosides

A

IV/IM

40
Q

Patients prescribed w Aminoglycosides should be tested/monitored for..

A
  1. avoid usage w other nephrotoxic drugs
    e.g. amphotericin B, vancomycin, NSAIDs & neuromuscular blocking agent
  2. therapeutic drug monitoring
    - peak & trough levels monitored to ensure no accumulation
  3. renal function tests - urea, creatinine, electrolytes
  4. precautionary measures to be taken when given to pxs w renal impairment, hearing defects & myasthenia gravis
41
Q

Resistance to aminoglycosides can occur via

A
  1. increased efflux pumps to reduce effective intracellular concentrations
  2. gram neg bacteria produce aminoglycoside inactivating enzymes
  3. alteration of 30S ribosomal subunit
  4. inhibition of aminoglycoside uptake by bacteria
42
Q

Aminoglycosides are first line for..

A

First line defence tx for multi-drug resistant (MDR) tuberculosis (mycobacterium tuberculosis

43
Q

Aminoglycosides mostly effective against..

A

Bacteria that are 1. Aerobic & 2. Gram negs
- enterobacteriaceae
- klebsiella & e.coli
- MDR microbes such as pseudomonas & acinetobacter

  • is first line against MDR tuberculosis
  • empiric therapy for serious infections such as epticemia, complicated UTIs, nosocomial RTIs
  • less effective in anaerobic environments such as abscess or infected bone
  • also act synergistically w b-lactams against certain gram +ve bacteria

y2 pharmaco (22 decks)

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