Tetracyclines

Question 1

What are the tetracyclines? Which is a second generation? 3rd generation?

Answer 1

Chlortetracycline
Oxytetracycline
Tetracycline
Doxycycline (2nd)
Tigecycline (3rd)

Question 2

Are tetracyclines lipid or water soluble?

Answer 2

Lipid

Question 3

What is the mechanism of action for tetracyclines?

Answer 3

Protein synthesis inhibitor & prevents access of transfer RNA

Question 4

What is the spectrum of 1st generation tetracylcines?

Answer 4

All aerobes & anaerobes ++

Also leptospira, protozoa, mycoplasma, rickettsial

Question 5

What is the spectrum of the 2nd generation (doxycycline)?

Answer 5

All aerobes & anaerobes +++++

Question 6

Which tetracycline was used to control Anaplasma marginale?

Answer 6

Chlortetracycline

Question 7

What is the difference between 1st and 2nd generations concerning spectrum?

Answer 7

2nd generations have increased potency and less acquired resistance

Question 8

Why are 3rd generation Tigecyclines less susceptible to resistance?

Answer 8

Less susceptible to efflux pumps

Question 9

Are Tigecyclines effective against Pseudomonas?

Answer 9

No

Question 10

What gene allows aerobic bacteria to be resistant to tetracyclines?

Answer 10

tetX encodes for oxidation

Question 11

What are the routes of administration for tetracycline?

Answer 11

Oral only

Question 12

What are the routes of administration for chlortetracycline?

Answer 12

oral only

Question 13

What are the routes of administration for oxytetracycline?

Answer 13

Injectable (SQ?)
Ophthalmic topical
Oral

Question 14

What are the routes of administration for doxycycline?

Answer 14

oral, injection

Question 15

What is the only route of administration for Tigecycline?

Answer 15

Injection

Question 16

Are tetracyclines well absorbed from oral administration? IM? SQ?

Answer 16

20 - 40% PO in cattle

350mg/hd/day = 0.2 cc/kg/hd/day

Question 17

How is doxycycline eliminated?

Answer 17

Hepatic (bile & diffusion via intestinal tract)

Question 18

Why is doxycycline a good tetracycline choice for patients with renal impairment?

Answer 18

Renal component of doxycycline is minimal

Question 19

What is the % of protein binding of doxycycline in cats & dogs?

Answer 19

90% dogs

99% cats

Question 20

Why does plasma binding affect the tissue concentration of doxycycline?

Answer 20

Plasma binding decreases diffusion gradient based on free drug in plasma

Question 21

In what tissue is doxycycline most concentrated (@ 15% of plasma)?

Answer 21

Prostate

Question 22

What is the efficacy of tetracyclines most closely linked to?

Answer 22

Time of serum concentration above MIC

Question 23

Which tetracycline can you give once to foals for flexor tendon contraction? What adverse effect is a concern?

Answer 23

High dose, IV oxytetracycline

Renal damage

Question 24

Can tetracyclines decrease inflammation?

Answer 24

yes

Question 25

What is the major adverse effect of oxytetracycline? Which disease can exacerbate these effects?

Answer 25

Nephrotoxicity with 2x -3x label dose | Dehydration, renal disease

Question 26

What is an adverse juvenile/fetal effect of tetracyclines? Why?

Answer 26

Teeth staining because tetracyclines bind to Ca2+

Question 27

Why are tetracyclines an issue in exported food animals?

Answer 27

Binds to Ca2+ & stays in bone, will glow under Wood's lamp for months

Question 28

What are the GI effects of tetracyclines? Which species specifically?

Answer 28

Oral tetracycline in cats | Hair loss, colic, fever, depression

Question 29

Which route of administration should you give tetracyclines to a horse? Which route should you never give tetracycline to a horse? Why? Which tetracycline specifically?

Answer 29

Always IV oxytetracycline Never orally because GIT effects Always oral doxycycline IV doxycycline is fatal

Question 30

Which tetracycline should you only give oral and never IV? Why?

Answer 30

Doxycycline | They will die

Question 31

What is a concern with injectable tetracyclines in food animals?

Answer 31

Injection site lesions

Question 32

What other adverse effect is sometimes associated with tetracyclines?

Answer 32

Photosensitization