Macrolides

Question 1

what are the physicochemical properties of macrolides?

Answer 1

macrolide ring
lipid soluble
maintains activity in purulent debris

Question 2

how well are macrolides absorbed after oral administration?

Answer 2

well absorbed: 40-90%

Question 3

what is the distribution of macrolides?

Answer 3

concentrate intracellularly and widely distributed

Question 4

do macrolides pass through the blood brain barrier and blood-aqueous barrier?

Answer 4

no

Question 5

how are macrolides excreted?

Answer 5

largely through bile into fecees
enters urine in therapeutic concentrations but not major route of elimination

Question 6

what is the mechanism of action of macrolides?

Answer 6

inhibition of protein synthesis at the 50S ribosomal subunit

Question 7

are macrolides bacteriostatic or bactericidal?

Answer 7

mostly bacteriostatic but can be bactericidal in some cases

Question 8

what does the DNA gyrase do?

Answer 8

unwinds DNA before replication

Question 9

how common is cross-resistance to other macrolides and lincosamides?

Answer 9

common

Question 10

what are some common macrolide agents?

Answer 10

erythromycin
azithromycin
clarithromycin
tylosin
tilmicosin

Question 11

what type of inhibition is the macrolides class believed to have?

Answer 11

time-dependent

Question 12

why is erythromycin not used in adult horses?

Answer 12

diarrhea is common in adult horsses

Question 13

erythromycin has _________________ at low doses (sometimes used for this purpose) and often causes ________________ at antibiotic doses

Answer 13

prokinetic activity
intestinal spasms

Question 14

what is common in dogs with erythromycin?

Answer 14

vomiting

Question 15

what are the half-lives like of azithromycin and clarithromycin?

Answer 15

longer than erythromycin
tissue half-lives substantially exceed plasma half-lives

Question 16

what is the best/safest drug to use for Rhodococcus equi?

Answer 16

clarithromycin
usually combined with rifampin

Question 17

what is the feed additive of tylosin used for?

Answer 17

predominantly in food animals

Question 18

what is tylosin used for in small animals?

Answer 18

sometimes for large and small bowel diarrheas

Question 19

when is tylosin contraindicated?

Answer 19

in horses where it can cause colic and death

Question 20

who is tilmicosin cardiotoxic to?

Answer 20

ducks
goats
horses
pigs
humans

Question 21

who is tilmicosin used in?

Answer 21

cattle only
(rabbits and sheep)

Question 22

what are the long-acting repository products of tulathromycin, gamithromycin, and tidipirosin used for?

Answer 22

respiratory disease in food animals

Question 23

what is the effect of long-acting repository products of tulathromycin, gamithromycin, and tidipirosin from?

Answer 23

long half-life and distribution to tissues rather than protein binding

Question 24

who is long-acting repository products of tulathromycin, gamithromycin, and tidipirosin not for use in?

Answer 24

lactating dairy cattle: residue violations

Question 25

why are clavamox/unasyn and baytril such a popular combination?

Answer 25

complementary: together, get all four quadrants

Question 26

where do macrolides concentrate?

Answer 26

lung, prostate, milk macrophages other tissues

Question 27

do macrolides enter urine in therapeutic concentrations?

Answer 27

yes

Question 28

are macrolides time-dependent or concentration-dependent?

Answer 28

time-dependent inhibition

Question 29

do macrolides have a post-antibiotic effect on anything? what?

Answer 29

yes, gram positive organisms for some macrolides

Question 30

what is the four quadrant coverage of erythromycin and tylosin like?

Answer 30

E. coli: -, + for respiratory Staphylococcus: + Streptococcus: + anaerobe: *

Question 31

what activity do newer macrolides have?

Answer 31

against non-enteric gram negatives

Question 32

what are some important side effects of erythromycin?

Answer 32

prokinetic at low doses intestinal spasms at antibiotic doses diarrhea common in adult horses vomiting common in dogs

Question 33

how much gastrointestinal upset do azithromycin and clarithromycin cause?

Answer 33

less than erythromycin

Question 34

what is azithromycin used to treat in cats and dogs?

Answer 34

Bartonella

Question 35

what macrolides are used as a food additive?

Answer 35

tylosin tilmicosin

Question 36

what macrolides should you not use in horses?

Answer 36

tylosin erythromycin tilmicosin

Question 37

what is the food additive tilmicosin used for?

Answer 37

control respiratory disease: okay for pigs via this route

Question 38

what macrolide is cardiotoxic to ducks, goats, horses, pigs, and man if injected?

Answer 38

tilmicosin

Question 39

what does the injectable formulation of tilmicosin produce for bovine respiratory disease complex?

Answer 39

3 days of effective concentrations metaphylaxis

Question 40

what is the long-acting repository products of macrolides due to?

Answer 40

long half life and distribution to tissues

Question 41

can you use macrolides in lactating dairy cattle?

Answer 41

no- concentrates in milk