Lecture on Macrolides

1. MACROLIDES
- DR. JERIN

2. INTRODUCTION :
 Antibiotics with large lactone ring to which sugars are attached
 Currently used :
 Erythromycin
 Roxithromycin
 Clarithromycin
 Azithromycin

3. Antibacterial spectrum
 Narrow spectrum
 Aerobic, gram positive & few gram negative organism
 Streptococci
 Pneumococci
 Staphylococci
 Legionella
 C. diptheriae
 B. pertussis
 T. pallidum
 Mycoplasma

4. Mechanism of action

5. MACROLIDES
Bacteriostatic at
low
concentration
More effective
alkaline pH
Bacteriocidal at
high
concentration

6. RESISTANCE:
 Low permeability
 Inactivating enzymes
 Low affinity of ribosomes

7. Pharmacokinetics
 Food interferes with absorption
 Destroyed by gastric acid – hence administered as ENTERIC
COATED TABLETS
 Crosses placenta
 But does not cross blood brain barrier
 Plasma t
1
2
~ 1.5hrs
 Excreted through bile.

8. Adverse effects
 Hepatitis with cholestatic jaundice
 Increases intestinal motility
 Cardiac arrhythmias
 Reversible hearing impairment

9. Drug interaction
 Microsomal enzyme inhibitor

10. Uses :
 Atypical pneumonia
 Legionnaires pneumonia
 Whooping cough
 Streptococcal infection
 Staphylococcal infection
 Diphtheria
 Syphilis & gonorrhoea
 Tetanus
 Anthrax
 Topical : skin infections

11. Erythromycin
 Obtained from streptomyces erythreus

12. Roxithromycin
 Longer acting
 Acid stable
 More potent
 Better absorbed
 Does not interact with other drugs

13. Clarithromycin
 Longer acting
 Acid stable
 Better absorbed
 Uses :
 H pylori – triple regimen
 Atypical mycobacterial infections

14. Azithromycin
 T
1
2
~ 3 days
 No drug interaction
 Acid stable
 Better absorbed
 Uses :
 Atypical mycobacterial infection
 Mycobacterium avium complex

16. URINARY TRACT
INFECTION

17. Urinary antiseptics
 Drugs which exerts action only in urinary tract.
 NITROFURANTOIN
 METHENAMINE

18. NITROFURANTOIN
 Bacteriostatic
 Higher concentration – bactericidal
 Gram positive & negative organism
 Moa : damages dna & rna synthesis
 Pk : t
1
2
1hr ; attains high conc. in urine
 Adverse effects : nausea, vomiting, diarrhoea, allergic reaction, hemolytic
anaemia, turns urine dark brown
 Use : UTI

19. Methenamine mandelate
 Moa : releases formaldehyde in acidic urine. Bactericidal
Not effective against urea splitting organism as they can raise the pH
Acidic pH can be maintained using ascorbic acid, mandelic acid or hippuric
acid
 Effective against : e coli & gram negative organism
 Adverse effects : haematuria, chemical cystitis, painful micturition

20. Urinary analgesic
 PHENAZOPYRIDINE
 AZO dye
 Analgesic action on urinary tract
 Relieves symptoms of burning micturition, urgency & ↑ frequency.

21. Thank you …