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Macrolides Antibiotics
1. Presented By
Dr. Manoj Kumar
Assistant Professor
Dept. of Pharmacology
Adesh Medical College & Hospital Ambala Can’t
2. Introduction
The term Macrolide was originally given to
antibiotics produced by species of Streptomyces.
Erythromycin was discovered in 1952,
obtainedfromStreptomyces erythreus.
Its semi synthetic derivative
2
5. MOA
Inhibit protein synthesis
Bind at 50S ribosome
Nascent peptide chain at the A site is
prevented from moving back to P site
↓
↓ protein synthesis
Do not inhibit the 60s/40ssubunits of
mammalian cells
5
6. Mechanisms of drug resistance
Bacteria become less permeable to drug
Efflux of the drugs by active mechanism
Protection of ribosomal subunit = prevent binding site.
Chromosomal mutation produce drug inactivating enzymes
Alteration in 50S ribosomal drug binding site
6
11. Adverse effects
GIT: Nausea, vomiting, epigastric pain, diarrhoea
Hypersensitivity reactions: skin rash, fever,
hepatitis with jaundice
Reversible hearing impairment (at very high
dose)
Superinfection
Hepatitis with cholestatic jaundice
Caution: Avoid in liver disease
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12. ROXITHROMYCIN
Roxithromycin has same spectrum as of Erythromycin but
it is more potent against
Good eternal absorption and t1/2 of 12 hr
Dose 150 – 300 mg BD
THERAPEUTIC USES
Pharyngitis.
Respiratory infection.
Skin and soft tissue infection.
ENT
12
13. CLARITHROMYCIN
Alternative to Erythromycin
Antibacterial spectrum – Expanded
Also Mycobacterium Avium complex (MAC), other
atypical Mycobacteria
It is used to treat Respiratory tract infections
(pharyngitis/tonsillitis ).
Skin infections due to susceptible organisms (e.g. S.
pneumo, S. aureus, Hemophilus influenza, Chlamydia
pneumoniae, Mycoplasma).
H. pylori associated with peptic ulcer debases
Whooping cough, atypical pneumonia, skin and soft tissue
infection.
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15. AZITHROMYCIN
Once daily dosing (OD)
Inhibition of cytochromeP450
It has an extended spectrum compared to
Erythromycin.
Elimination by kidney & t½ is almost 3 days
it is effective even in a single dose.
Higher activity against Mycoplasma pneumoniae,
Nesseria gonorrhoeae, toxoplasma Gondi,
Chlamydia trachomatis .
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16. Advantages of azithromycin over
erythromycin are:
Azithromycin has excellent activity against H.
influenzae.
It is acid-stable
Rapidly absorbed
Has better tissue penetrability
Longer acting–once daily.
Azithromycin remains in the tissues for a long
period
Better tolerated than erythromycin.
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17. USE
Campylobacter jejuni (most common bacterial
infections of humans, food borne illness.)
H. Influenza (Meningitis, Epiglottis, Cellulitis,
Infectious arthritis).
Respiratory system infection, middle ear, eye,
central nervous system infection.
It is used to acute bacterial infection
17
18. .
Single dose treatment mild to moderate sinusitis
Chancroid ( STD; Caused by haemophilus
ducreyi)
T
o treat non gonococcal infections (urethritis,
cervicitis)
Prevention or treatment of MAC infection in
patients with advanced HIV.
ADVERSE REACTIONS:
Pseudo membranous colitis,
Abdominal pain, Nausea /Vomiting,
Rash
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19. Comparative features of macrolides
Erythromycin Roxithromycin Clarithromyci
n
Azithromycin
Source Natural Semisynthetic Semisynthetic Semisynthetic
DOA Short acting
(6 h)
Long acting
(12 h)
Long acting Long acting
Acid
stability
Alkaline stable Acid stable Acid stable Acid stable
Antibac
spectrum
Narrow
spectrum
Narrow
spectrum
Expanded: +
MAC, M.leprae,
H.pylori
Expanded: +
MAC,
H.influenzae,
Salmonella,
malaria
Enzyme
inhibition
+ _ + _
Dose 250-500 mg
QID *7d
150 mg BD* 7d 250 mg BD *1-2
wks
500 mg OD * 3-
5d
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20. Drug interactions
With Cisapride, Terfendine: ↓CYP3A4 → ↑
QT, Ventricular Arrhythmias & Death
CYP-450 inhibitor: ↑ levels of Theophylline,
Warfarin, Carbamazepine, Valproate
Not seen with Azithromycin
21. Newer Macrolides
Dirithromycin, Oleandomycin, Trolendamycin,
Spiramycin, Ketolides, Telithromycin
Advantages
Broader spectrum
Acid-stable
Longer t1/2
Less toxicity
Mainly used in respiratory tract infection