Macrolide AB - 5Qs Flashcards
Explain the meaning of Macrolides AB
Macro = large (14-16 memebered ring)
Lied = lactose glycoside
MOA of Macrolide AB
ALL are bacterioSTATIC
Are Macrolide ABs acidic or basic?
Bases
Name the most common Macrolide ABs used.
Salts and esters of erythromycin
Which Macrolide ABs is produced naturally?
Erythromycin (Saccharopolyspora erythraea)
All the rest are semi-synthetic
Name the target of Macrolide ABs
Inh of protein biosynthesis
Following binding to the 50s ribosomal subunit
What other ABs do Macrolide ABs share a common target with?
What’s the result of this similarity?
Lincosamides and chloramphenicol
They are CLINICALLY CROSS RESISTANT with one another
Name agents that are Macrolide ABs
Erythromycin
Clarothromycin
Azithromycin
Dirithromycin
What other ABs are equivalent to Macrolide ABs
1st gen Cephalosporin and 2nd gen Penicillin
What m.o. is most susceptible to Macrolide ABs
Legionella (gram -ve)
Mycoplasma (miscellaneous m.o.)
What m.o. are susceptible to Macrolide ABs
Gram tve - strep, staphy, Corneybacterium, B. anthracis
Gram -ve - Legionella, Haemophilis
Anaerobes - propionibacteria
Miscellaneous m.o. - Mycoplasma, Ureoplasma, Chlamydia, Rickettisiae
When do Macrolide ABs find special utility?
In pts allergic to Penicillin
List clinical uses of oral Macrolide ABs
Upper and lower respiratory tract inf. (Strep Pneumonia)
Upper and lower respiratory tract and otitis media (H. Influenza + sulfonamide)
Mycoplasmal pneumonia
Skin and soft tissue (streptococcus pyrogenes)
Legionnaires dx (Legionella)
What is Macrolide ABs used for PROPHYLAXIS?
Bacterial endocarditis (Strep viridans)
Similar to Pen G
What’s Macrolide ABs combo with to treat Mycobacterium avium complex inf in. AIDS, and somewhere STDs?
Rifabutin
What Macrolide ABs is used to treat gastric ulcer due to H. Pylori?
Clarithromycin
How does resistance dev to Macrolide ABs
Alteration of ribosomal target (50S ribosome) by METHYLATION of a ribosomal DNA base leading to weaker binding of AB
What mediates the resistance?
R-factor mediated.
Name alternate resistance to Macrolide ABs
Efflux pump
Reduced uptake
By destroying enzymes e.g. esterases and phosphotransferases
Effect of food on Erythromycin
Absorption is irregular with food.
Propulsive agent (Motilin agonist) causing GI upset
What does liver metabolism of the ff entail
A. Erythromycin
B. Clarithromycin
A. N-demethylation
B. C-hydroxylation at C-14
Effect of erythromycin on CP450
Erythromycin can inh P-450 enzymes t4 affecting several drugs e.g.
Carbamazepine, cyclosporine, terfernadine, midazolam, warfarin
What is the effect of erythromycin on astemizole and terfernadine?
Could lead to v serious CV effect e.g. fibrillation and Arrythmias