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Pharmacology > Aminoglycoside & Tetracyclines > Flashcards

Aminoglycoside & Tetracyclines Flashcards

1
Q

Aminoglycoside and tetracycline are which drug inhibitor classification?

A

Protein synthesis inhibitor (30S ribosomal subunits)

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2
Q

Tetracycline is bactericidal or bacteriostatic?

A

Bacteriostatic

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3
Q

List example of drug for high therapeutic index and low therapeutic index.

A

High TI: Penicillin, Cephalosporin, macrolides

Low TI: Chloramphenicol, aminoglycoside & tetracycline

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4
Q

Mechanism of resistance for aminoglycoside and tetracycline

A
  1. Enzyme inactivation-aminoglycoside, beta lactam and chloramphenicol.
  2. Decreased drug permeability - loss specific channel : aminoglycoside, tetracycline
  3. Development of efflux pump: tetracycline
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5
Q

Steps in bacterial protein synthesis

A
  1. Initiation
  2. Transpeptidation
  3. Elongation
  4. Translocation of the polypeptide
  5. Termination of protein synthesis
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6
Q

MOA of tetracyclines

A
  • tetracycline enter the organisms via passive diffusion and by energy dependent transport protein mechanism to the bacterial inner cytoplasmic membrane.
  • tetracycline concentrate intracellularly in susceptible organisms.
  • it bind reversible to 30S subunit of the bacterial ribosome.
  • this actions prevents binding of tRNA to the mRNA-ribosome complex, thereby inhibiting bacterial protein synthesis.
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7
Q

Mechanism of resistance of tetracycline

A
  1. An efflux pump that expel drugs out of the cell, thus preventing intracellular accumulation.
  2. Enzymatic inactivation of the drug
  3. Production of bacterial proteins that prevent tetracycline from binding to the ribosome.
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8
Q

Antibacterial spectrum of tetracycline

A

Gram positive & gram negative bacteria, protozoa, spirochetes, mycobacteria & atypical species

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9
Q

Pharmacokinetic of tetracycline

A

Absorption:

  • adequately absorbed after oral ingestion.
  • administration of dairy product or other substance that contain magnesium, aluminium antacids or iron supplement decrease absorption.

Distribution:

  • concentrate well in a bile, liver, kidney, gingival fluid and skin.
  • all tetracycline cross the placental barrier and concentrate in fetal bones and dentition.

Elimination:

  • it is not hepatic ally metabolised.
  • Primarily eliminated unchanged in the urine.
  • doxycycline is preferred in renal compromised patient, as it primarily eliminated via bile and feces.
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10
Q

Classification of tetracycline

A

Short acting: tetracycline, chlortetracycline

Immediate acting: demeclocycline

Long acting: doxycyclines, minocycline

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11
Q

Uses of tetracycline

A
  • atypical pneumonia (mycoplasma pneumoniae)
  • pelvic inflammatory disease
  • plaque prophylaxis
  • Rickettsia
  • relapsing fever
  • Borrelia
  • chlamydia
  • StDs
  • Cholera
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12
Q

Tetracycline is contraindicated?

A
  • pregnant women

- renal impaired patients

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13
Q

Adverse effect of tetracycline

A
  1. Gastrointestinal disturbance: Epigastrc distress result from irritation of gastric mucosa and is often responsible for non-compliance with tetracycline.
  2. Superinfection
  3. Pseudomembranous colitis (diarrhea, increase of clostridium difficile)
  4. Tooth discolouration : deposition in the bone and primary dentition occur during the calcification process in growing children.
  5. Hepatic necrosis
  6. Phototoxicity :severe sunburn may occur in patient receiving a tetracycline who are exposed to the sun or ultraviolet rays.
  7. Vestibular problem
  8. Pseudocerebri
  9. Antianabolic
  10. Diabetes insipidus
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14
Q

Glycylcyclines, example of drug

A

Tigecycline, a derivative of minocycline

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15
Q

MOA tigecycline

A

-Reversibly binding to the 30S ribosomal subunit and inhibiting protein synthesis.

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16
Q

Antibacterial spectrum of tigecycline

A

-MRSA, multidrug resistant streptococci, vancomycin - resistant Enterococci (VRE)

17
Q

Resistance mechanism of tigecycline

A

Overexpression of efflux pumps

18
Q

Clinical use of tigecycline

A

-MRSA, skin, soft tissue infections and complicated intra-abdominal infections

19
Q

Adverse reaction of tigecycline

A

Nausea

20
Q

Tigecycline is bacteriostatic or bactericidal?

A

Bacteriostatic

21
Q

List example of aminoglycoside drugs

A

-Gentamicin, Neomycin, streptomycin, Amikacin and Tibramycin.

Aminoglycoside derives from

  • streptomyces have - mycin suffix
  • micromonospora end in - micin
22
Q

Aminoglycoside is bactericidal or bacteriostatic?

A

Bactericidal

23
Q

MOA aminoglycoside

A

-binds to 30S ribosomes subunit and distort its structure, thus interfering with the initiation of protein synthesis. They also allow misreading of the mRNA code, causing mutation or premature chain termination.

Main point

  • stops initiation
  • interfere with polysome formation
  • misreading of mRNA code
  • premature chain termination
24
Q

Resistance of mechanism in aminoglycoside

A
  1. Efflux pump
    2 decrease uptake
  2. Modification and inactivation by plasmid associated synthesis of enzyme
25
Q

Pharmacokinetic of aminoglycoside

A

Absorption:
-highly polar, polycationic structure that prevent adequate absorption after oral administration. Thus, it must be given parenteral to achieve adequate serum levels except neomycin.

Distribution :

  • cannot enter CNS or eye except neomycin
  • high concentration accumulate in:
    a) renal cortex
    b) endolymph and perilymph of the inner ear.
    c) crosses placental barrier

Distribution :

  • excreted unchanged in the urine.
  • accumulation occurs in patients with renal dysfunction, dose adjustment are required.
26
Q

Adverse effect of aminoglycoside

A
  1. Ototoxicity: auditory and vestibular is directly related to high peak plasma levels and the duration of treatment.
  2. Nephrotoxicity : retention of the aminoglycoside by the proximal tubular cells disrupts calcium-mediated transport process.
  3. Neuromuscular paralysis: associated with rapid increase in concentration or concurrent administration with neuromuscular blockers.
  4. Allergic reactions: contact dermatitis is a common related to topically applied neomycin

Pharmacology (16 decks)

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