Antibiotic therapy Flashcards
macrolides
What is the parent drug of macrolides and why has it gone out of favor
Erythromycin is the parent drug
It has a propensity to cause GI signs such as diarrhea and vomiting (as it is a pro-kinetic)
It is degradated in the presence of gastric acid, so most oral formulations are enteric-coated
What is the difference between azithromycin, clarithromycin and erythromycin
azithromycin and clarithromycin are azalide derivatives of erythromycin with increased resistance to degradation by gastric acids, and better enteral absorption
What is the specificity of azithromycin regarding the activity against Mycoplasma when compared to other macrolides
Azithromycin has been found to be ineffective against M. haemofelis
What are frequent indications for clarithromycin use
clarithromycin is often used for the treatment of mycobacterial, helicobacter and rhodococcus equi infections
It may also be useful against Toxoplasma gondii
What is the mechanism of action of macrolides
They act in a similar way to tetracyclines by blocking protein production, however they reversibly bind to the large (50S), rather than the small ribosomal subunit
They accumulate in leukocytes, thus theyr are transported directly to the site of infection
They are primarily effective against gram-positive bacteria, chlamydia, mycoplasma, helicobacter and campylobacter
They are usually bacteriostatic and are mostly time-dependent drugs (except for azithromycin)
How macrolides tend to affect the metabolism of other drugs such as cyclosporine, omeprazole or theophylline
They inhibit the cytochrome P450 system
