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Pharmacology > Ch 39 - Protein Synthesis Inhibitors > Flashcards

Ch 39 - Protein Synthesis Inhibitors Flashcards

1
Q

Bacterial ribosomes:

A

30S and 50S subunits

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2
Q

Mammalian ribosomes:

A

40S and 60S subunits

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3
Q

Tetracyclines consist of:

A

4 fused rings with a system of conjugated double bonds

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4
Q

How does tetracyclines enter susceptible organism?

A

via passive diffusion and also by an energy-dependent transport protein mechanism unique to the bacterial inner cytoplasmic membrane.

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5
Q

What does the tetracyclines bind to?

A

it binds reversibly to the 30S subunit of the bacterial ribosome

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6
Q

What does the binding of the tetracycline to the 30s subunit do?

A

This action prevents binding of tRNA to the mRNA ribosome complex, thereby inhibiting bacterial protein synthesis

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7
Q

Where does the tetracyclines concentrate in susceptible organisms

A

concentrate intracellularly in susceptible organisms

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8
Q

Are tetracyclines bactericidal or bacteriostatic?

A

The are bacteriostatic antibiotics effective against a wide variety of organisms, including gram positive and gram-negative bacteria, protozoa, spirochetes, mycobacteria, and atypical species.

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9
Q

What do we use to treat acne?

A

tetracyclines

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10
Q

What do we use to treat Chlamydia infections?

A

tetracyclines

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11
Q

What do we use tetracyclines for?

A

They are commonly used in the treatment of acne and Chlamydia infections (doxycycline).

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12
Q

Doxycycline =

A

Chlamydia infections

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13
Q

Tetracyclines resistance

A
  • the most commonly occurring resistance is an efflux pump that expels drug out of the cell, thus preventing intracellular accumulation.
  • enzymatic inactivation of the drug and production of bacterial proteins that prevent tetracyclines from binding to the ribosome.
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14
Q

How is the resistance to the other tetracyclines when the resistance to one of them occur

A

Resistance to one tetracycline does not confer universal resistance to all tetracyclines.

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15
Q

Tetracyclines target the…….

A

30S subunit and prevent binding of tRNA to mRNA

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16
Q

Aminoglycosides bind to the……..

A

30S subunit, distorting its structure and causing misreading of the mRNA

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17
Q

Erythromycin and clindamycin bind to the……

A

50S subunit, thus inhibiting translocation

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18
Q

Chloramphenicol inhibits……

A

peptidyl transferase

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19
Q

Linezolid binds the……

A

23S ribosomal RNA preventing formation of the 70S initiation complex

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20
Q

How well are the tetracyclines absorbed after oral ingestion?

A

Tetracyclines are adequately absorbed after oral ingestion.

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21
Q

In what forms are both doxycycline and minocycline available?

A

Both doxycycline and minocycline are available as oral and intravenous (IV) preparations

22
Q

In what forms are both doxycycline and minocycline (both tetracyclines) available?

A

Both are available as oral and IV preparations

23
Q

Tetracycline distribution:

A
  • concentrate well in the bile, liver, kidney, gingival fluid, and skin.
  • they bind to tissues undergoing calcification (for example, teeth and bones) or to tumors that have a high calcium content.
  • penetration into most body fluids is adequate.
24
Q

What happens with the tetracyclines if they are administered in a pregnant woman?

A

All tetracyclines cross the placental barrier and concentrate in fetal bones and dentition

25
Q

What happens with the tetracyclines if they are administered in a pregnant woman?

A

All tetracyclines cross the placental barrier and concentrate in fetal bones and dentition

26
Q

What can we use minocycline to treat and why?

tetracyclines

A

minocycline achieves high levels in saliva and tears, rendering it useful in eradicating the meningococcal carrier state.

27
Q

Which tetracyclines are not hepatically metabolizied?

A
  • tetracycline

- doxycycline

28
Q

How are tetracyclines metabolized?

A
  • primarily eliminated unchanged in the urine

- minocycline undergoes hepatic metabolism and is eliminated to a lesser extent via the kidney.

29
Q

Which drug is preferred in renally compromised patients, and why?

A

doxycycline is preferred, as it is primarily eliminated via the bile into the feces.

30
Q

What are the adverse effect of tetracyclines?

A
  • GI disturbance
  • Effects on calcified tissues/ Deposition of drug in bones and teeth
  • Hepatotoxicity
  • Phototoxicity
  • Vestibular dysfunction
  • Pseudotumor cerebri
  • Avoid in pregnancy and when breast-feeding!!
  • Not to be given to children less than 8yrs
  • Hypersensitivity reactions (drug fever, skin rashes) (uncommon)
  • venous thrombosis
31
Q

GI disturbance (tetracyclines):

A
  • Epigastric distress commonly results from irritation of the gastric mucosa and is often responsible for noncompliance with tetracyclines.
  • Esophagitis may be minimized through coadministration with food (other than dairy products) or fluids and the use of capsules rather than tablets.
32
Q

When should the tetracyclines be taken?

A

Tetracycline should be taken on an empty stomach.

33
Q

Effects of tetracyclines on calcified tissues:

A

Deposition in the bone and primary dentition occurs during the calcification process in growing children. This may cause discoloration and hypoplasia of teeth and a temporary stunting of growth.
- use of tetracyclines is limited in pediatrics.

34
Q

Vestibular dysfunction:

A
  • dizziness, vertigo, and tinnitus may occur particularly with minocycline, which concentrates in the endolymph of the ear and affects function.
  • doxycycline may also cause vestibular dysfunction.
35
Q

Pseudotumor cerebri:

A
  • Benign, intracranial hypertension characterized by headache and blurred vision may occur rarely in adults.
  • Although discontinuation of the drug reverses this condition, it is not clear whether permanent sequelae may occur
36
Q

How are most tetracyclines absorbed? (metabolism)

A

Most tetracyclines are reabsorbed from bile, metabolized to glucuronides, and excreted in the urine

37
Q

Doxycycline metabolism:

A

it is excreted via the bile

38
Q

What is Tigecycline a derivative of?

A

minocycline

39
Q

What is a derivative of minocycline

A

tigecycline

40
Q

What is the first available member of the glycylcycline antimicrobial class?

A

tigecycline

41
Q

What is tigecycline used to treat?

A

It is indicated for the treatment of complicated skin and soft tissue infections, as well as complicated intra abdominal infections.

42
Q

What is tigecycline effect on the protein synthesis?

A

Tigecycline exhibits bacteriostatic action by reversibly binding to the 30S ribosomal subunit and inhibiting protein synthesis

43
Q

Tigecycline spectrum:

A
  • broad-spectrum activity
  • however, tigecycline is not active against
    • Morganella
    • Proteus
    • Providencia
    • Pseudomonas species
44
Q

What does the antibacterial spectrum of tigecycline include?

A
  • methicillinresistant staphylococci (MRSA)
  • multidrug-resistant streptococci
  • vancomycin-resistant enterococci (VRE)
  • extended spectrum β-lactamase–producing gram negative bacteria
  • Acinetobacter baumannii
  • many anaerobic organisms
45
Q

Tigecycline resistance:

A
  • it was developed to overcome the recent emergence of tetracycline class–resistant organisms that utilize efflux pumps and ribosomal protection to confer resistance.
  • However, resistance is seen and is primarily attributed to overexpression of efflux pumps.
46
Q

Tigecycline

A
  • Following IV infusion, tigecycline exhibits a large volume of distribution.
  • It penetrates tissues well but has low plasma concentrations. Consequently, tigecycline is a poor option for bloodstream infections.
47
Q

What is the primary route of elimination of tigecycline?

A

the primary route of elimination is biliary/fecal.

48
Q

Are any dosage adjustments necessary for patients with renal impairment?

A

No dosage adjustments are necessary for patients with renal impairment.

49
Q

Are any dosage adjustments necessary for patients with severe hepatic dysfunction

A

a dose reduction is recommended

50
Q

Tigecycline adverse effect:

A
  • nausea and vomiting.
  • acute pancreatitis, including fatality
  • elevations in liver enzymes and serum creatinine
  • photosensitivity
  • pseudotumor cerebri
  • discoloration of permanent teeth when used during tooth development
  • fetal harm when administered in pregnancy
  • may decrease the clearance of warfarin and increase prothrombin time
51
Q

What is tigecycline coadministered with?

A

tigecycline is coadministered with warfarin

Pharmacology (11 decks)

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