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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
What happens with the tetracyclines if they are administered in a pregnant woman?
All tetracyclines cross the placental barrier and concentrate in fetal bones and dentition
26
What can we use minocycline to treat and why? | tetracyclines
minocycline achieves high levels in saliva and tears, rendering it useful in eradicating the meningococcal carrier state.
27
Which tetracyclines are not hepatically metabolizied?
- tetracycline | - doxycycline
28
How are tetracyclines metabolized?
- primarily eliminated unchanged in the urine | - minocycline undergoes hepatic metabolism and is eliminated to a lesser extent via the kidney.
29
Which drug is preferred in renally compromised patients, and why?
doxycycline is preferred, as it is primarily eliminated via the bile into the feces.
30
What are the adverse effect of tetracyclines?
- 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
GI disturbance (tetracyclines):
- 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
When should the tetracyclines be taken?
Tetracycline should be taken on an empty stomach.
33
Effects of tetracyclines on calcified tissues:
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
Vestibular dysfunction:
- 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
Pseudotumor cerebri:
- 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
How are most tetracyclines absorbed? (metabolism)
Most tetracyclines are reabsorbed from bile, metabolized to glucuronides, and excreted in the urine
37
Doxycycline metabolism:
it is excreted via the bile
38
What is Tigecycline a derivative of?
minocycline
39
What is a derivative of minocycline
tigecycline
40
What is the first available member of the glycylcycline antimicrobial class?
tigecycline
41
What is tigecycline used to treat?
It is indicated for the treatment of complicated skin and soft tissue infections, as well as complicated intra abdominal infections.
42
What is tigecycline effect on the protein synthesis?
Tigecycline exhibits bacteriostatic action by reversibly binding to the 30S ribosomal subunit and inhibiting protein synthesis
43
Tigecycline spectrum:
- broad-spectrum activity - however, tigecycline is not active against * Morganella * Proteus * Providencia * Pseudomonas species
44
What does the antibacterial spectrum of tigecycline include?
- methicillinresistant staphylococci (MRSA) - multidrug-resistant streptococci - vancomycin-resistant enterococci (VRE) - extended spectrum β-lactamase–producing gram negative bacteria - Acinetobacter baumannii - many anaerobic organisms
45
Tigecycline resistance:
- 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
Tigecycline
- 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
What is the primary route of elimination of tigecycline?
the primary route of elimination is biliary/fecal.
48
Are any dosage adjustments necessary for patients with renal impairment?
No dosage adjustments are necessary for patients with renal impairment.
49
Are any dosage adjustments necessary for patients with severe hepatic dysfunction
a dose reduction is recommended
50
Tigecycline adverse effect:
- 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
What is tigecycline coadministered with?
tigecycline is coadministered with warfarin

Pharmacology (11 decks)

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