Macrolides Flashcards
what are the physicochemical properties of macrolides?
macrolide ring
lipid soluble
maintains activity in purulent debris
how well are macrolides absorbed after oral administration?
well absorbed: 40-90%
what is the distribution of macrolides?
concentrate intracellularly and widely distributed
do macrolides pass through the blood brain barrier and blood-aqueous barrier?
no
how are macrolides excreted?
largely through bile into fecees
enters urine in therapeutic concentrations but not major route of elimination
what is the mechanism of action of macrolides?
inhibition of protein synthesis at the 50S ribosomal subunit
are macrolides bacteriostatic or bactericidal?
mostly bacteriostatic but can be bactericidal in some cases
what does the DNA gyrase do?
unwinds DNA before replication
how common is cross-resistance to other macrolides and lincosamides?
common
what are some common macrolide agents?
erythromycin
azithromycin
clarithromycin
tylosin
tilmicosin
what type of inhibition is the macrolides class believed to have?
time-dependent
why is erythromycin not used in adult horses?
diarrhea is common in adult horsses
erythromycin has _________________ at low doses (sometimes used for this purpose) and often causes ________________ at antibiotic doses
prokinetic activity
intestinal spasms
what is common in dogs with erythromycin?
vomiting
what are the half-lives like of azithromycin and clarithromycin?
longer than erythromycin
tissue half-lives substantially exceed plasma half-lives
what is the best/safest drug to use for Rhodococcus equi?
clarithromycin
usually combined with rifampin
what is the feed additive of tylosin used for?
predominantly in food animals
what is tylosin used for in small animals?
sometimes for large and small bowel diarrheas
when is tylosin contraindicated?
in horses where it can cause colic and death
who is tilmicosin cardiotoxic to?
ducks
goats
horses
pigs
humans
who is tilmicosin used in?
cattle only
(rabbits and sheep)
what are the long-acting repository products of tulathromycin, gamithromycin, and tidipirosin used for?
respiratory disease in food animals
what is the effect of long-acting repository products of tulathromycin, gamithromycin, and tidipirosin from?
long half-life and distribution to tissues rather than protein binding
who is long-acting repository products of tulathromycin, gamithromycin, and tidipirosin not for use in?
lactating dairy cattle: residue violations
why are clavamox/unasyn and baytril such a popular combination?
complementary: together, get all four quadrants
where do macrolides concentrate?
lung, prostate, milk
macrophages
other tissues
do macrolides enter urine in therapeutic concentrations?
yes
are macrolides time-dependent or concentration-dependent?
time-dependent inhibition
do macrolides have a post-antibiotic effect on anything? what?
yes, gram positive organisms for some macrolides
what is the four quadrant coverage of erythromycin and tylosin like?
E. coli: -, + for respiratory
Staphylococcus: +
Streptococcus: +
anaerobe: *
what activity do newer macrolides have?
against non-enteric gram negatives
what are some important side effects of erythromycin?
prokinetic at low doses
intestinal spasms at antibiotic doses
diarrhea common in adult horses
vomiting common in dogs
how much gastrointestinal upset do azithromycin and clarithromycin cause?
less than erythromycin
what is azithromycin used to treat in cats and dogs?
Bartonella
what macrolides are used as a food additive?
tylosin
tilmicosin
what macrolides should you not use in horses?
tylosin
erythromycin
tilmicosin
what is the food additive tilmicosin used for?
control respiratory disease: okay for pigs via this route
what macrolide is cardiotoxic to ducks, goats, horses, pigs, and man if injected?
tilmicosin
what does the injectable formulation of tilmicosin produce for bovine respiratory disease complex?
3 days of effective concentrations
metaphylaxis
what is the long-acting repository products of macrolides due to?
long half life and distribution to tissues
can you use macrolides in lactating dairy cattle?
no- concentrates in milk
