Antimicrobials 4 Flashcards
what other beneficial effects do macrolides have other than antibacterial?
One of the safest classes of antibacterial drugs
Also have anti-inflammatory effects
pharmacokinetics of macrolides
- Penetrate cells better than most drug
classes - Concentrate in lung & lung macrophages
- Erythromycin, the first to be discovered, has a short half-life; newer macrolides have long half-lives
- Weak bases
mechanism of action for macrolides
Inhibit protein synthesis
Bacteriostatic effect
spectrum of activity for erythromycin (a macrolide)
Relatively broad
-Gram positive aerobes
-Anaerobes
-Some Gram negative aerobes (but not enterobacteriaceae)
-Some atypical bacteria
important uses for erythromycin
- Intracellular pathogens
- Respiratory infections
- In place of penicillin in animal with allergy
Erythromycin inhibits P450 enzymes,
(unlike most newer macrolides)
Increases T1/2 of other drugs that are metabolized by same enzymes (e.g., omeprazole, theophylline)
spectrum of activity for newer macrolides
- Most effective against Gram-negative aerobes (usually more effective than erythromycin)
>some efficacy against all other bacterial types
newer macrolides in veterinary medicine are generally used for what species?
livestock
* Several injectable drugs approved for livestock
Human-labelled drugs sometimes used for bacterial pneumonia in non-food- producing animals (horses, small animals)
how does the half life of newer macrolides compare with that of erythromycin
Longer half-lives: once-a-day admin
Newer macrolides approved for livestock are used mainly for the treatment of
respiratory disease
what is tilmicosin? what is it used for? what bacteria is it effective against? administration consideration?
Tilmicosin - macrolide
* For bacterial pneumonia
* Effective mainly against Gram-negative aerobic lung pathogens
* IV injection fatal; fatal to swine and various other non-approved species
what is tulathromycin? used in what species and for what diseases? effective against what kind of bacteria? half life?
Tulathromycin - macrolide
-used in cattle and swine for bacterial pneumonia
-Effective mainly against Gram-negative aerobic lung pathogens of cattle & swine
T1⁄2 = ~90 h; lung elimination T1⁄2 = ~1 week
>single dose therapy
what is gamithromycin and what is it used for?
Another similar new macrolide
* Single SC therapy for bovine resp. disease
macrolides resistance profile and mechanism
- May develop during therapy, due to mutation of ribosomal gene encoding efflux pump
- Acquisition of plasmid-encoded efflux pump
macrolides main adverse effects
1) Tissue irritation
* IM injection: severe pain from chemical irritation
* PO: vomiting – erythromycin stimulates motilin receptors (much more than newer macrolides)
> prokinetic GI effects > nausea +/- diarrhea; effect is highly variable from animal to animal
2) Oral toxicity in herbivores: potentially fatal rumen stasis, risk of serious colitis in hindgut fermenters (horses, rabbits) even by other routes
3) Tilmicosin can cause rapid cardiac fatalities in several species other than cattle (humans, swine, goats, horses) when administered parenterally
macrolides flash card: mechanism of action
Inhibition of protein synthesis (bacteriostatic effect)