Macrolide

By Pulse MBBS visit as at pulsembbs.blogspot.com

MACROLIDE


WHAT ARE MACROLIDES?

• They are antibiotics having a macrocyclic lactone ring with attached sugars.

• THE COMMONLY USED MACROLIDES ARE:ErythromycinClarithromycinRoxithromycinAzithromycin


ERYTHROMYCIN

• First isolated from Streptomyces erythreus in 1952

• Widely employed as an alternative to penicillin


MECHANISM OF ACTION

• It is bacteriostatic at low conc & bactericidal at high conc

• Bactericidal property depends on the conc, organism concerned and its rate of multiplication

• Erythromycin acts by inhibiting bacterial protein synthesis. It combines with 50s ribosome subunits and prevent translocation.


ANTIMICROBIAL SPECTRUM• It is a narrow spectrum antibiotic• Spectrum is similar to Pencillin G. Mostly gram +ve and few

gram –ve bact. • Str. pyogenes , Str. Pneumonia, N. gonorrhoea, Clostridium, C.

diphtheriae and Listeria• In addition, Campylobacter, Legionella, Branhamella

catarrhalis, G. vaginalis and Mycoplasma (which are not affected by pencillin are also highly susceptible to erythromycin)

• Moderately sensitive to H. ducreyi, H. influenza, B. pertussis, C. trachomatis, N. meningitidis and Rickettsiae

• Ineffective against Enterobacteriaceae, other gram negative bacilli and B. fragilis


RESISTANCE

• All cocci develop resistance, mostly by acquiring capacity to pump it out. Most of the resistance are plasmid mediated.

• Bacteria that develop resistance to erythromycin shows cross resistance with other macrolides.

• Cross resistance with clindamycin and chloramphenicol can also occur


Pharmacokinetics

• Its acid labile, so protect it from gastric acid its given as enteric coated tablets

• Erythromycin is widely distributed in the body, enters cells and into abscesses, crosses serous membranes and placenta, but not BBB

• Major excretion through liver. Renal excretion is minor


Adverse Effects

1. Gastrointestinal – epigastric pain, diarrhea2. Reversible hearing loss3. Hypersensitivity – fever, rash

Interaction• It inhibits hepatic oxidation of many drugs – it rises

plasma level of theophylline, carbamazepine, valproate, ergotamine and warfarin


USES• As an alternative to penicillin

1. Streptococcal pharyngitis, tonsillitis, mastoiditis and CAP2. Alternative prophylaxis for RF and SABE3. Diphtheria4. Tetanus as an adjuvant to TT5. Syphilis and gonorrhoea6. Leptospirosis

• As a first choice drug for1. Atypical pneumonia caused by Mycoplasma2. Whooping cough3. Chancroid


NEWER MACROLIDES

• ROXITHROMYCIN• CLARITHROMYCIN• AZITHROMYCIN• SPIRAMYCIN

Macrolide

Health & Medicine

Transcript of Macrolide