Azithromycin Clinical Pharmacokinetics

Abstract

Azalide antibiotics, of which azithromycin is the first demonstrated, have different pharmacokinetics from other antibiotics currently used. The bioavailability of the drug is approximately 37%. Extensive and rapid distribution from serum into the intracellular compartments is followed by rapid distribution to the tissues. Tissue concentrations exceed serum concentrations by up to 100-fold following a single azithromycin 500mg dose. Concentration of the drug within phagocytes aids in its ability to combat infections. High concentrations of azithromycin are found in the tonsil, lung, prostate, lymph nodes and liver, with only small concentrations found in fat and muscle. A 500mg dose on day 1, followed by 250mg daily on days 2 to 5, has been demonstrated to maintain azithromycin concentrations at sites of infection and continues to be effective for several days after administration has ceased. The pharmacokinetics of azithromycin make it a drug with diverse therapeutic applications.

Antimicrobial Susceptibility to Azithromycin among Salmonella enterica Isolates from the United States

“…In addition, azithromycin is increasingly considered for the management of bacillary dysentery and invasive nontyphoidal Salmonella infections (9,10,37,38). Azithromycin shows excellent penetration into most tissues, and it achieves concentrations in macrophages and neutrophils that are Ͼ100-fold higher than concentrations in serum (23,29). These properties, along with azithromycin's long half-life of 2 to 3 days, have increased azithromycin's role in the therapeutic management of infections of the reticuloendothelial system.…”

Pharmacokinetic Properties of Azithromycin in Pregnancy

“…Azithromycin (AZI) is a semisynthetic azalide antibiotic that is structurally related to erythromycin but has a broader spectrum of antibacterial activity and a more favorable pharmacokinetic profile (13,22). It is widely used in the treatment of respiratory and sexually transmitted infections, including those in HIV-infected patients (32,34).…”

Isolation of multidrug-resistant Salmonella in Singapore

“…(3,4) In vitro studies have demonstrated azithromycin's excellent tissue penetration and ability to achieve high intracellular concentrations (> 100 times higher than serum) in macrophages and neutrophils, coupled with a long half-life of 2-3 days. (11,12) Thus, it has been increasingly favoured for the management of bacillary dysentery and invasive non-typhoidal Salmonella infections. However, the clinical breakpoints for Salmonella and azithromycin have yet to be defined.…”