1. General information
1.1. antibiotics
1.2. large macrocyclic lactone ring to which deoxy sugars are attached
1.3. fist macrolide was erythromycin
1.4. semi-synthetic derivatives (commonly used)
1.4.1. roxithromycin
1.4.2. clarithromycin
1.4.3. azithromycin
1.5. Ketolides are active against some macrolide-resistant strains
1.5.1. semi-synthetic derivatives
1.5.2. example: telithromycin
2. Mechanism of action
2.1. bacteriostatic (inhibit protein synthesis)
2.2. binds irreversibly to 50 S ribosomes
2.3. same or close to binding site of chloramphenicol (so they antagonize each other)
3. Antimicrobial spectrum
3.1. gm+
3.1.1. cocci
3.1.1.1. streptococci
3.1.1.2. staphylococci
3.1.2. bacilli
3.2. gm-
3.2.1. cocci
3.3. other
3.3.1. mycobacteria
3.3.2. mycoplasma
3.3.3. ureaplasma
3.3.4. spirochetes
4. pharmacokinetics
4.1. Erythromycin
4.1.1. absorbed from upper small intestines (enteric coated tablet)
4.1.2. food delay absorption but reduce side effects
4.1.3. plasma protein binding affinity 70-80%
4.1.4. 5-20% of serum concentration crosses placenta
4.1.5. 50% in milk
4.2. Clarithromycin
4.2.1. rapidly absorbed from GI
4.2.2. reduced bioavailability due to first pass metabolism
4.2.2.1. metabolized in the liver to 14 hydroxy clarithromycin (active form)
4.2.3. tissue concentration > serum co.
4.2.4. plasma protein binding affinity 40-70%
4.2.5. elimination half life 3-7 hours, and 5-9 hours for the active form
4.3. Azithromycin
4.3.1. rapid and widely distributed (except brain and CSF)
4.3.2. plasma protein binding 50%
4.3.3. 12% eliminated unchanged in urine
4.3.4. elimination half life is 40-68 hours due to extensive distribution
5. Therapeutic uses
5.1. Respiratory tract infections
5.1.1. erythromycin
5.1.1.1. upper and lower reps. tract infection
5.1.1.1.1. strept. pyogenes
5.1.1.1.2. strept. pneumoniae
5.1.1.1.3. mycoplasma pneumonia
5.1.1.2. whooping cough (B. pertussis)
5.1.2. clarithromycin and azithromycin
5.1.2.1. mild to moderate community acquired pneumonia
5.2. Skin and soft tissue infections
5.2.1. alternative agents
5.2.1.1. strept. pyogenes
5.2.1.2. staph. aureus
5.3. Diphtheria
5.3.1. Erythromycin 250mg
5.4. Campylobacter infections
5.4.1. gastroenteritis
5.4.1.1. erythromycin 250-500mg
5.5. Helicobacter pylori infection
5.5.1. peptic ulcer is treated by combination of
5.5.1.1. clarithromycin 500mg
5.5.1.2. omeprazole 20mg
5.5.1.3. amoxicillin 1gm
5.6. Mycobacterial infections
5.6.1. clarithromycin or azithromycin
5.6.2. treating M. avium in AIDS patients
5.6.3. pulmonary disease in non HIV patients
5.7. Prophylactic uses
5.7.1. erythromycin
5.7.1.1. alternative for patients allergic to penicillin
5.7.1.2. prophylaxis of rheumatic fever
5.7.2. clarithromycin or azithromycin
5.7.2.1. alternatives for prevention of bacterial endocarditis for patients doing dental procedures
6. Adverse effects
6.1. Erythromycin causes heptotoxicity and epigastric distress
6.2. clarithromycin and azithromycin have the same side effects but at lower rate
6.3. Erythromycin and clarithromycin causes ventricular techycardia
6.4. allergenic reactions may occur
6.4.1. ototoxicity after IV erythromycin (deafness)
6.5. Drug interactions
6.5.1. Erythromycin and clarithromycin inhibit CYP3A4
6.5.1.1. thus increase the effect of these drugs
6.5.1.1.1. carbamzepine
6.5.1.1.2. corticosteroids
6.5.1.1.3. cyclosporine
6.5.1.1.4. digoxin
6.5.1.1.5. theophylline
6.5.1.1.6. valproate
6.5.1.1.7. warfarin