Topic 12-Tetracyclines and Glycylcyclines

Question 1

What is the mechanism of action of tetracyclines

Answer 1

The drug binds reversibly to the 30s subunit of the bacterial ribosome

Question 2

What are the two short acting tetracycline derivatives

Answer 2

tetracycline and oxytetracycline

Question 3

What are the long-lasting tetracycline derivatives

Answer 3

doxycycline (most commonly used) and minocycline

Question 4

How long are tetracycline and oxytetracycline active for?

Answer 4

6-8 hours

Question 5

How long is doxycycline and minocycline active for

Answer 5

16-18 hours

Question 6

What is the spectrum of tetracyclines

Answer 6

Broad spectrum
Gram +/-/aerobes/anaerobes
-intracellular bacteria (2nd choice drug after macrolides and fluoroquinolones
mycoplasma, chlamydia, ureaplasmalytica 
Rickettsiae (1st choice drug!!)
-some parasitse 
protozoa, p. falciparum
-Zoonotic bacteria
borrelia, francisella (with aminoglycosides), brucella, yersinia pestis
-cholera
-H. pylori
mycolasma and legionella
-Does NOT treat
gonococci, pseudomonas, acinetobacter, and proteus (90% resistant)

Question 7

Pharmacokinetics of tetracyclines
Bactericidal or bacteriostatic?
Absorption?
Distribution?
Administration?
Elimination?

Answer 7

Bactericidal
Good GI absorption (DO NOT take with dairy, will form chelate and become inactive)
Distribution is good (bile, liver, kidney, saliva, skin, and placenta)
Administered Orally and maybe even IV once a day
Eliminated mainly through urine (short acting only through kidney) and partly through bile (if there is a kidney issue then don’t need to change dose as it will continue to be excreted by bile)

Question 8

Indications for tetracyclines

Answer 8

Prostatitis, gynecological infections, zoonotic infections, same as spectrum

Question 9

Adverse effects of tetracyclines

Answer 9

1. )Chelate formation-avoid milk/iron pills/antacids that form complexes which bind bones and teeth (dental staining under the age of 8-12, contraindicated in pregnancy)
2. )GI disturbences- pseudomembrane colitis and nausea
3. )Photosensitivity
4. )ulceration of esophageal mucosa with doxycycline (hydrate with pill)
5. )Hepatotoxicity over 4 grams of dose
6. )Acute renal acidosis leading to fanconi syndrome when taking expired pills

Question 10

What is the Glycylcyclines drug

Answer 10

Tigecycline

Question 11

Spectrum of Tigecycline

Answer 11

Broad spectrum including MRSA, VRE
Vancomycin resistant staph and strep
penicillin reistant enterococci
Enterobactericae
Rickettsia, chlamydia, legionella, and mycobacteria
NOT effective against Pseudomonas and proteus

Question 12

Pharmacokinetics of Tigecycline
Distribution
Administration
Half-life
Excretion

Answer 12

Distribute well to tisssue
Administered 2 times a day parenterally (IV)
40 hour half life
excreted in bile, a little through urine

Question 13

Clinical indication

Answer 13

skin/soft tissue infection and intra-abdominal infections

Question 14

Adverse effects

Answer 14

1. )Nausea, vomiting
2. )Acute pancreatitis
3. )Elevation in liver enzyme/serum creatinin
4. )Tetracycline effects