(Mode of Action of Drugs)

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Chapter

1.4

Chapter

9.5 Macrolide and Polypeptide Antibiotics

MACROLIDE ANTIBIOTICS

Macrolides, as their name indicates are
characterized by a large or macrocyclic
lactone ring with attached sugar
residue(s). They are classified as in table
9.5.1

ERYTHROMYCIN

Erythromycin was the first macrocyclic
antibiotic which was isolated from
Streptomyces erythreus. Erythromycin is
widely used antibiotic both in children as
well as in adults.

It acts by binding with 50S ribosomal
subunit of bacteria and inhibit protein
synthesis.

It is a narrow spectrum antibiotic,

low concentration are bacteriostatic,

however high concentrations are bacte-

ricidal. The spectrum of activity also de-

pends on the concentration of drug at

the desired site and sensitivity of the tar-

get microorganisms. It is more active in

alkaline medium.

Erythromycin is effective against gram

positive and few gram negative organisms

which mainly includes pneumococci,

streptococci, staphylococci, Neisseria and

some strains of C. diphtheriae, H. influenzae,

Rickettsiae and Treponema. It is also effective

against penicillin resistant staphylococci,

Macrolide and

Polypeptide

Antibiotics

Table 9.5.1: Classification of macrolide antibiotics.

Erythromycin 250-500 mg QID

as stearate (RESTOMYCIN)

as estolate (ALTHROCIN)

also as ethyl succinate, 0.4-0.6 g every 6 hourly (drop & syrup)

and gluceptate 0.5-1.0 g IV 6 hourly

Roxithromycin (ROXID) 150 mg BD

Azithromycin (ZATHRIN) 500 mg OD

Clarithromycin (CLAMYCIN) 250-500 mg BD

Clindamycin (DALACIN-C) 150-300 mg QID oral, 200-600 mg TDS IV

Lincomycin (LYNX) 500 mg TDS-QID oral, 600 mg IV 6-12 hourly

Vancomycin (FORSTAF) 250-500 mg 6 hourly