Tetracyclines and Sulfonamides

Question 1

mechanism of action for tetracyclines

Answer 1

inhibition of protein synthesis (bacteriostatic effect)

Question 2

main adverse effects of tetracyclines (4)

Answer 2

-incorporation into growing long bones and teeth
-nephrotoxicity in dehydrated patients
-tissue irritation (pain on injection; vomiting oral dose)
-risk of esophageal damage in cats

Question 3

general spectrum for all species with tetracyclines

Answer 3

all species = atypical bacteria (usually drug of choice)

Question 4

general spectrum for livestock with tetracyclines

Answer 4

broad spectrum

Question 5

what line of use are tetracyclines according to health canada

Answer 5

first line

Question 6

PK feature of tetracyclines

Answer 6

lipid soluble tetracyclines (doxycycline for ex) are useful against intracellular pathogens

Question 7

mechanism of action of sulphonamides

Answer 7

inhibition of folic acid synthesis

Question 8

general spectrum for all species with sulphonamides

Answer 8

atypical bacteria, UTIs

Question 9

main adverse effects of sulphonamides (3)

Answer 9

-lacrimotoxicity in dogs (KCS)
-nephrotoxicity in dehydrated patients
-hypersensitivity (including contact dermatitis)

Question 10

general spectrum for livestock with sulphonamides

Answer 10

fairly broad spectrum

Question 11

line of use of sulphonamides according to health canada

Answer 11

first line

Question 12

PK features of sulphonamides (2)

Answer 12

-ineffective in presence of pus
-distribute to all tissues

Question 13

what are tetracyclines commonly used for in livestock

Answer 13

wide variety of bacterial infections

Question 14

what can affect absorption of oral tetracyclines

Answer 14

divalent cations in food (calcium in milk, cheese) can markedly inhibit oral absorption

Question 15

what specific tetracycline enters the host cell well and why

Answer 15

doxycycline, its the most lipid soluble so it enters the cell well (incl. prostate and CNS)

Question 16

is resistance common for tetracyclines

Answer 16

yes

Question 17

main mechanism for tetracyclines

Answer 17

-efflux pump

• Removes drug from bacterial cell
• Efflux pump may be overwhelmed by high drug concentration -> explains improved efficacy with topical application in some situations

Question 18

are sulphonamides effective when used alone

Answer 18

no

Question 19

what is potentiated sulfonamides

Answer 19

effectiveness of the sulfonamides is restored when combined with trimethoprim

largely used in LA medicine

Question 20

TMS combinations are ____ and _____

Answer 20

synergystic and bactericial

Question 21

are sulphonamides effective in the presence of pus

Answer 21

no… puscontains huge amounts of GABA