Tetracyclines

Question 1

Mechanism of action

Answer 1

Inhibition of protein synthesis 30S (bacteriostatic)

High cc has -cidal effect -> in urine high- UTI treatment

Question 2

Mode of action

Answer 2

Generally bacteriostatic, but high cc- bacteriocidal

Question 3

Pharmacokinetic

Answer 3

Excellent absorption.

Penetrate BBB, blood-milk, blood-prostate, penetrate cell= mycoplasma, erlichia, chlamydia, rickettsia.

Question 4

Spectrum

Answer 4

Gram+, Gram-, aerobic, anaerobic.
NO PSEUDOMONAS
Resistance is common :(
Mycoplasma- resp. tract inf.
Rickettsia
Chlamydia- tetracycline is the 1st choice.
Wohlbachia- HW treatment. Doxycycline 10 mg/kg 2x/d 30 days.
Borrelia- lyme disease
Anaplasma- doxycycline
Bordetella bronchoseptica- kennel cough, atrophic rhinitis- all tetracycline, but doxycycline is prefered.
Some protozoa- babesia, theileria, entamoeba histolytic, plasmodium

Question 5

Structure

Answer 5

4 rings- very lipophilic

Question 6

Classifications

Answer 6

Short acting: tetracycline, oxytetracycline, chlortetracycline
Intermediate acting: demeclocycline
Long acting: Doxycycline, minocycline - these discolour teeth.

Question 7

Natually occuring:

Answer 7

tetracycline, oxytetracycline, chlortetracycline

Question 8

Semisynthetically:

Answer 8

Doxycycline, Minocycline

Question 9

Mechanism of resistance:

Answer 9

Impaired uptake: bacteria don’t let in
Active efflux pump
Antibiotic degrading enzyme, altering enzyme
Resistant bacteria is common.
Ab ovo- Pseudomonas
Aquired: E.coli, Salmonella- almost always resistant,

Pasteurella, Mannheimia, Strepto, Staphyl= 50%

Question 10

Pharmacokinetic- Classic TTC

Answer 10

Aborption: moderate/ weak. Decrease with food. DON’T take with milk!

Distribution: Good

Metabolism: Low

Excretion: Mainly urine

Question 11

Pharmacokinetic- long acting

Answer 11

Absorption: Good

Distribution: Excellent

Metabolism: Low- but little higher than TTC

Excretion: bile- large intestines.

Can give to liver-and kidney patients.
Don’t use in UTI.

Question 12

Indications and application

Answer 12

General infections- bronchopneumonia (1st choice in), 
foot disease, 
(UTI- but there is better choices), 
metritis- intrauterine, 
mastitis- intramammary

Question 13

Specific conditions:

Answer 13

Lyme disease and Erlichiosis- doxycycline.
Chlamydia
Feline mycoplasmosis
Infectious keratoconjuctivitis- moraxella bovis, injection
Prolifierative enteropathy in horse
Lawsonia intracellularis- swine and horse- doxycycline (this disease is lethal if left untreated)
Nocardiosis, heart water, anaplasmosis
Heart worm treatment

Question 14

Side effects

Answer 14

Tissue irritation- wash esophagus after oral application- water or food. (can lead to necrosis!)
Diarrhea, vomiting
Dysbacteriosis- horse and rabbit, herbivore rodents.
Rapid application IV- can lead to collapse.
(Bind to Ca -> hypocalcemia -> decrease contractability of heart.) APPLY VERY SLOWLY!
Nephrotoxic
Hepatotoxic-> photosensitivity

Question 15

Short acting:

Answer 15

Tetracycline
Oxytetracycline
Chlortetracycline

Question 16

Intermediate acting:

Answer 16

Demeclocycline

Question 17

Long acting:

Answer 17

Doxycycline, Minocycline

Discolour teeth and bone.

Question 18

Which discolour?

Answer 18

Long acting- doxycycline, minocycline.