Macrolide Antibiotics
                     Macrolide 
Antibiotics
INTRODUCTION
Macro l ides  are  ant ib iot ics  that  are  pr imar i ly  
bacter iostat ic ;  by b inding to the 50S subuni t  of  
the r ibosome,  they inhibi t  bacter ia l  prote in 
synthesis .
Source: www.msdmanuals.com
What are Macrolides?
Macro l ides  are a c lass  of  ant ibiot ics  der ived from 
Saccharopolyspora erythraea (or iginal ly  cal led 
Streptomyces erythreus) ,  a type of  soi l -borne 
bacter ia .
Source: www.drugs.com
How it affects?
Macro l ides  inhib i t  prote in synthesis  in bacter ia by 
revers ib ly  binding to the P s i te  of  the 50S uni t  o f  
the r ibosome.  
Macro l ides  mainly  aff ect  gram-posi t ive cocc i  and 
intracel lu lar  pathogens such as mycoplasma,  
chlamydia,  and legione l la.
Source: www.drugs.com
Indications for Macrolides
1. Aerobic  and anaerobic  gram-posi t ive  cocc i ,  
except for  most  enterococci ,  many 
Staphylococcus aureus stra ins (especia l ly  
methic i l l in- res istant  stra ins) ,  and some 
Streptococcus pneumoniae and S.  pyogenes 
stra ins
2. Mycoplasma pneumoniae
3. Chlamydia  t rachomat is
4. Chlamydophi la  pneumoniae
Source: www.msdmanuals.com
Choice for group A 
1. Macro l ides  have been considered the  drug of  
choice for  group A streptococcal  and 
pneumococcal  infect ions when penic i l l in  cannot  
be used.  
2. However,  pneumococci  wi th reduced penic i l l in  
sensi t iv i ty are often res is tant  to  macrol ides,  
and macrol ide res is tance among S.  pyogenes 
var ies g lobal ly.  
Source: www.msdmanuals.com
Contraindications to 
Macrolides
1. Macro l ides  are contraindicated in pat ients who 
have had an al le rgic  react ion to  them.
Source: www.msdmanuals.com
Use During Pregnancy and 
Breastfeeding
1. Erythromycin is  considered compatib le  with 
breast feeding.  Safety of  other macrol ides  
dur ing breastfeeding is  unknown.
Source: www.msdmanuals.com
Adverse Effects of 
Macrolides
1. Gastro intest inal  (GI)  d is turbances (main ly  with 
erythromycin)
2. QT- interval  prolongation
3. Inhibi t ion of  hepat ic  metabol ism, leading to  
numerous drug interact ions
Source: www.msdmanuals.com
Dosing Considerations for 
Macrolides
1. For az i thromycin,  no dosage adjustment is  
requi red for  renal  insuffi ciency.
2. Erythromycin and,  to some extent ,  
c lar i thromycin interact  with numerous drugs 
because they inhibi t  hepat ic metabol ism v ia the  
cytochrome P-450 (CYP450) system.  
Azi thromycin is  the  least  l ike ly  to  interact  wi th 
other drugs.
Source: www.msdmanuals.com
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