Erimycin For Suspension Mechanism of Action

Pharmacology: Pharmacodynamics: Erythromycin is a macrolide antibacterial with a broad and essentially bacteriostatic action against many Gram-positive and to a lesser extent some Gram-negative bacteria. Erythromycin binds to the 50S ribosomal subunit of susceptible organisms, resulting in inhibition of protein synthesis and hence inhibition of cell growth.
Erythromycin is active against: Gram-positive such as Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, Viridans group streptococci, Listeria monocytogenes, Corynebacterium diphtheriae and Corynebacterium minutissimum.
Gram-negative organism including Haemophilus influenzae, Moraxella catarrhalis, Bordetella pertussis, Legionella pneumophila and Neisseria gonorrhoeae.
Some strains of Chlamydia trachomatis, Mycoplasma pneumoniae, Treponema pallidum, Ureaplasma urealyticum, Entamoeba histolytica and Clostridium tetani.
Pharmacokinetics: Absorption: Erythromycin base is an unstable in gastric acid and absorption is variable and unreliable. The bioavailability is 18-45%. Erythromycin ethylsuccinate is an ester of Erythromycin suitable for oral administration. The ester is generally more reliably and quickly absorbed. Erythromycin ethylsuccinate is partially dissociated in the intestine where both erythromycin and the undissociated ester are absorbed. In the blood, the ester is partially hydrolyzed to release free erythromycin. Peak serum concentrations given orally in 4 doses daily are higher than single dose. Oral administration of 400 mg of Erythromycin ethylsuccinate 4 times daily maintains antibacterial serum concentrations of 0.1-2 mcg/mL. Time to peak serum of Erythromycin ethylsuccinate is 1-2 hours.
Erythromycin ethylsuccinate may be administered without regard to meals.
Distribution: Erythromycin is widely distributed throughout body tissue and fluids. Although it does not cross the blood-brain barrier well and low concentrations (2-13% of serum concentrations) are distributed into CSF. Erythromycin base is 73-81% bound to serum proteins.
Metabolism: Erythromycin is partly metabolized in the liver by the cytochrome P450 isoenzyme CYP3A4 by N-demethylation to inactive, unidentified metabolites.
Elimination: Erythromycin is mainly excreted unchanged via bile and undergoes intestinal reabsorption. About 2-15% of an oral dose is excreted unchanged in the urine. Only small amounts of erythromycin are removed by hemodialysis. The half-life of Erythromycin is about 1.5 to 2.5 hours. In patients with renal impairment may be prolonged half-life and has been reported to be between 4 to 7 hours.