Kinetics of erythromycin uptake and release by human lymphocytes and polymorphonuclear leucocytes

For macrolides, clinical activity but also the development of bacterial resistance has been attributed to prolonged therapeutic and subtherapeutic concentrations. Although erythromycin is a long-established antimicrobial, concomitant determination of the pharmacokinetics of erythromycin and its metabolites in different compartments is limited. To better characterize the pharmacokinetics of erythromycin and its anhydrometabolite (anhydroerythromycin [AHE]) in different compartments during and after the end of treatment with 500 mg of erythromycin four times daily, concentration-time profiles were determined in plasma, interstitial space of muscle and subcutaneous adipose tissue, and white blood cells (WBCs) at days 1 and 3 of treatment and 2 and 7 days after end of therapy. In WBCs, concentrations of erythromycin exceeded those in plasma approximately 40-fold, while free concentrations in plasma and tissue were comparable. The observed delay of peak concentrations in tissue might be caused by fast initial cellular uptake. Two days after the end of treatment, subinhibitory concentrations were observed in plasma and interstitial space of both soft tissues, while 7 days after the end of treatment, erythromycin was not detectable in any compartment. This relatively short period of subinhibitory concentrations may be advantageous compared to other macrolides. The ratio of erythromycin over AHE on day 1 was highest in plasma (2.81 ؎ 3.45) and lowest in WBCs (0.27 ؎ 0.22). While the ratio remained constant between single dose and steady state, after the end of treatment the concentration of AHE declined more slowly than that of the parent compound, indicating the importance of the metabolite for the prolonged drug interaction of erythromycin. Macrolides account for 10 to 15% of the worldwide consumption of antibiotics (25,31). Although in many countries erythromycin has been replaced by newer relatives like azithromycin and clarithromycin, prescription of erythromycin still has a substantial place in less developed countries but also certain regions within Europe (15, 40). However, bacterial resistance against macrolides dramatically escalated in many countries during the last decades (14,23,35). Total consumption of antimicrobials on the one hand and the presence of long periods of exposure of bacterial populations to subinhibitory concentrations of antibiotics on the other hand are considered critical factors for selecting bacterial resistance (2, 3, 16).Erythromycin is known for its highly variable bioavailability after oral ingestion and its susceptibility toward degradation under acidic conditions. Although its half-life in plasma is short and the pharmacokinetic (PK) profile intraindividually heterogeneous, it is very well distributed throughout body tissues and accumulates in leukocytes (11). While clinical studies have shown the effectiveness of erythromycin in skin and soft tissue infections (33, 39), the in vivo penetration and the resulting free concentrations in interstitial space of soft tissues, i.e., the ...

Section: Discussionsupporting

confidence: 93%

Section: Discussionsupporting

confidence: 92%

Blood, Tissue, and Intracellular Concentrations of Erythromycin and Its Metabolite Anhydroerythromycin during and after Therapy

Krasniqi

Matzneller

Kinzig

et al. 2012

“…These findings are in marked contrast to what we have observed with other highly concentrated antibiotics (clindamycin, erythromycin), which are promptly released from alveolar macrophages and PMNs upon removal of extracellular drug (18,26). Other investigators have also observed a rapid efflux of macrolide antibiotics (osamycin, rokitamycin, clarithromycin, and roxithromycin, in addition to erythromycin) from human PMNs, lymphocytes, and tissue culture cells (6,17,23 (25).…”

Section: Resultscontrasting

confidence: 66%

Interactions of dirithromycin with human polymorphonuclear leukocytes

Hand

1993

Dirithromycin, a new macrolide antibiotic, achieves prolonged, high levels in tissue. We previously demonstrated that certain macrolides are highly concentrated within phagocytic cells. This background information prompted us to evaluate the interactions of dirithromycin and human polymorphonuclear leukocytes (PMNs). After incubation with radiolabeled dirithromycin, antibiotic uptake by PMNs was determined by a velocity-gradient centrifugation technique and was expressed as the ratio of the cellular to the extracellular drug concentration (C/E). Dirithromycin was avidly accumulated by PMNs (C/E, 5 at 15 min, 10 at 30 min, 19 at 1 h, and 35 at 2 h). Uptake was dependent on cell viability, physiologic environmental temperature, and pH (optimum 8.6), but was not influenced by potential competitive inhibitors of membrane transport. Incubation with sodium cyanide caused an increase in dirithromycin accumulation by PMNs. Ingestion of microbial particles (mimicking in vivo infection) modestly inhibited the entry of dirithromycin into PMNs. After removal of extracellular drug, the efflux (release) of dirithromycin from PMNs was slow; only 10% was released within the first 30 min. This prolonged retention of dirithromycin within phagocytic cells might allow delivery and release of accumulated drug at sites of infection. The impact of intraphagocytic dirithromycin on cellular function was also evaluated. In a manner similar to that of other highly concentrated, weakly basic antibiotics, dirithromycin inhibited the respiratory burst response (superoxide production) in stimulated PMNs. The presence of dirithromycin slightly increased the intraphagocytic killing of Staphylococcus aureus in human PMNs. These interactions of dirithromycin with phagocytic cells may promote the extraphagocytic, and possibly the intraphagocytic, killing of infecting organisms.

“…Potential cooperation between an antibiotic and the immune system is particularly important in patients with impaired immune function, such as patients with acquired immune deficiency syndrome. Erythromycin and macrolides show excellent penetration of polymorphonuclear leukocytes, macrophages, and lymphocytes (5,11,18,25,26). This is particularly important in infections with Legionella spp., Mycobacterium spp., Listeria spp., Brucella spp., Staphylococcus aureus, Toxoplasma spp., and Chlamydia spp., which are known to survive intracellularly.…”

Section: Macrolides and The Immune Systemmentioning

confidence: 99%

New directions for macrolide antibiotics: pharmacokinetics and clinical efficacy

Kirst

Sides

1989

156

Erythromycin and related macrolide antibiotics have recently enjoyed a resurgence of clinical interest. This is a result of activity against organisms which are becoming more prevalent, particularly in immunocompromised hosts and, in addition, better understanding of the unique tissue penetration properties and potential immunomodulating properties of macrolides. Other features of clinical interest possessed by certain of the newer macrolides include the potential for once-daily dosing, resistance to acid degradation in the stomach without enteric coating, and possibly reduced gastrointestinal side effects. The new macrolides are expected to retain the clinical indications of erythromycin, which include upper and lower respiratory tract infections, skin and skin structure infections, and genital tract infections caused by erythromycin-susceptible organisms. In addition, enhanced activity has been demonstrated in animal models and in vitro against toxoplasma, Legionella, Haemophilus, and Campylobacter spp. New macrolide derivatives also show promise to expand the antimicrobial spectrum of erythromycin to include Mycobacterium and Borrelia spp.