Elthrocin Tablet Mechanism of Action

Pharmacology: Pharmacodynamics: Mode or Mechanisms of Action: Erythromycin is a bacteriostatic macrolide antibiotic. However, it may be bactericidal in high concentrations or when used against highly susceptible organisms. It is thought to penetrate the bacterial cell membrane and to reversibly bind to the 50 S subunit of bacterial ribosomes; it does not directly inhibit peptide formation, but rather inhibits the translocation of peptides from the acceptor site on the ribosome to the donor site, inhibiting subsequent protein synthesis. Erythromycin is effective only against actively dividing organisms.
Erythromycin is a broad-spectrum antibiotic with activity against gram-positive and gram-negative bacteria, and other infectious agents, including Chlamydia trachomatis, mycoplasmas (Mycoplasma pneumoniae and Ureaplasma urealyticum), and spirochetes (Treponema pallidum and Borrelia species).
Erythromycin has good activity against Streptococcus pneumoniae, S. pyogenes (group A beta-hemolytic streptococci), and Staphylococcus aureus.
Many other Gram-positive organisms respond to erythromycin including Bacillus anthracis, Corynebacterium diphtheriae, Erysipelothrix rhusiopathiae, and Listeria monocytogenes, and it is usually moderately effective against the anaerobic Clostridium spp. Nocardia spp. vary in their susceptibility, but erythromycin is effective against Propionibacterium acnes.
Gram-negative cocci include Neisseria meningitidis and N. gonorrhoeae, and Moraxella (Branhamella) catarrhalis.
Erythromycin also has good activity against certain gram-negative bacteria, including Legionella pneumophila, Helicobacter pyloridis, Campylobacter jejuni, and Bordetella pertussis, some Brucella strains, Flavobacterium, and Pasteurella. Haemophilus ducreyi is reportedly susceptible, but H. influenzae is somewhat less so. Erythromycin is synergistic with sulphonamides against Haemophilus influenza.
Pharmacokinetics: Absorption: Erythromycin stearate is acid-labile so is given in film-coated tablets. The stearate is hydrolysed in the intestine and the free erythromycin absorbed. Its absorption is delayed by food. High carbohydrate, fat and protein meals reduce the absorption of the stearate by 53 - 64%. Bioavailability varies between 30 and 65%, depending on the salt.
Distribution: Erythromycin is widely distributed throughout body tissues and fluids. Only low concentrations are normally achieved in the cerebro-spinal fluid, but passage of the drug across the blood - brain barrier increases in meningitis. In the presence of normal hepatic function, erythromycin is concentrated in the liver, bile and spleen.
Protein binding: 70 to 75% protein bound; 85% to α₁ acid glycoprotein and the remainder to albumin.
Metabolism: >90%, partially inactivated by N-demethylation in the liver but concentration of active drug in bile is high and there is evidence of enterohepatic circulation.
Half-life: Normal renal function: 1.4 to 2.5 hours.
Anuric patients: Approximately 5 hours.
Time to peak concentration: Single dose of 250mg: Approximately 0.8 mcg/mL at 3 hours.
Excretion: Excreted in the bile; 2 - 5% of an oral dose is excreted in active form in the urine. Erythromycin crosses the placental barrier and is excreted in breast milk.