MACROLIDES ANTIBIOTICS

Chemistry : macrocyclic lactone ring with attached sugars
The drugs in this group are
Erythromycin
Roxithromycin
Clarithromycin
Azithromycin
Mechanism of action: act by inhibiting bacterial protein synthesis
Combine with 50 s ribosome subunit & interfere with translocation
Spectrum : overlaps with that of penicillin G
Narrow spectrum, mostly against gram positive
S. pyogenes, S. pneumonae, N. gonorrhoe, Clostridia, C. diptherae, Listeria, Campylobacter, Legionella, B. catarrhalis, Gardenerella & Mycoplasma
PK: erythromycin base is acid labile, given as enteric coated tablets, widely distributed in body but not cross BBB, partly metabolized & excreted primarily in bile
Erythromycin base
Erythromycin stearate
Erythromycin estolate
ADR:
GIT: due to stimulation of motilin receptors in GIT
Hypersensitivity: hepatitis with cholestatic jaundice resembling viral hepatitis occurs with estolate ester after 1-3 weeks, incidence is higher in pregnant women, it clears on discontinuation of drug
Reversible hearing impairment on high dose
Interaction : erythromycin is enzyme inhibitor, it increase the level of theofylline, carbamazapine, valproate & warfain
QT prolongation
Uses: As alternative to penicillin in
Streptococcal infection
Diptheria
Tetanus
Syphilis & gonorrhoea
Leptospirosis
First choice for:
Atypical pneumonia caused by M. pneumonae
Whooping cough caused by B. pertusis
Chancroid caused by H. ducryi
As a second choice in:
Campylobacter enteritis
Legionnares pneumonia
Chlamydia trachomatis
Penicillin resistant staphylococcal infections