Affiliation:
1. INSERM U 479, Laboratoire d’Hématologie et Immunologie, CHU X. Bichat, 75018 Paris,1 and
2. Anti-Infective Research Department, Hoechst-Marion-Roussel, 93235 Romainville,2 France
Abstract
ABSTRACT
HMR 3647, a new ketolide, is active upon intracellular pathogens. We previously demonstrated that HMR 3004 (RU 64004), another ketolide, is highly concentrated by human polymorphonuclear neutrophils (PMNs). This prompted us to evaluate whether the presence of a 3-keto group instead of an
l
-cladinose, a neutral sugar characteristic of erythromycin A derivatives, confers peculiar pharmacokinetic properties with regard to cellular accumulation and efflux. After incubation with the radiolabelled drug, HMR 3647 uptake was determined by a velocity gradient centrifugation technique. HMR 3647 was avidly concentrated by PMNs, without saturation, over a 3-h incubation period, with cellular-to-extracellular concentration ratios of 31 ± 4.2 at 5 min and up to 348 ± 27.1 at 180 min. About 60% of HMR 3647 was located in the granular compartment; less than 6% was associated with the membranes. HMR 3647 gradually egressed from loaded cells placed in drug-free medium. Uptake was dependent on environmental temperature (activation energy, 128 ± 9.4 kJ/mol) but not on extracellular pH. HMR 3647 displayed Michaelis-Menten saturation kinetics with a mean
V
max of 2315 ng/2.5 × 10
6
PMNs/5 min and a mean
K
m
of 117 mg/liter (144 μM). As already observed with erythromycin A-derived macrolides, extracellular Ca
2+
was necessary for optimal uptake of HMR 3647. Interestingly, verapamil increased the uptake of HMR 3647 at 5 min, but this was followed by gradual inhibition at later incubation times, a phenomenon probably related to stimulation of drug efflux. The impact of intracellular accumulation of HMR 3647 on PMN functions was also investigated. In contrast to other erythromycin A derivatives, HMR 3647 only weakly triggered granule exocytosis, but it inhibited superoxide anion production in a time- and concentration-dependent manner, with concentrations which inhibited 50% of control response of 55 (67 μM) (5 min) and 30 (36 μM) (30 min) mg/liter for formyl-methionyl-leucyl-phenylalanine stimulation and 117 (143 μM) (5 min) and 44 (54 μM) (30 min) mg/liter for phorbol myristate acetate stimulation.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Reference36 articles.
1. Erythromycin A-derived macrolides modify the functional activities of human neutrophils by altering the phospholipase D-phosphatidate phosphohydrolase transduction pathway.;Abdelghaffar H.;J. Immunol.,1997
2. Abdelghaffar
H.
Labro
M. T.
Effect of RU 64004 on oxidant production by human neutrophils abstr. F-225
Program and abstracts of the 36th Interscience Conference on Antimicrobial Agents and Chemotherapy.
1996
139
American Society for Microbiology
Washington D.C
3. Effects of dirithromycin and erythromycylamine on human neutrophil degranulation
4. Agouridas
C.
Bonnefoy
A.
Chantot
J. F. In vitro antibacterial activity of HMR 3647 a novel ketolide highly active against respiratory pathogens abstr. F-112
Program and abstracts of the 37th Interscience Conference on Antimicrobial Agents and Chemotherapy.
1997
165
American Society for Microbiology
Washington D.C
5. Araujo-Khan
F.
Bryskier
A.
Remington
J.
Ketolides are active against Toxoplasma gondii abstr. F-251
Program and abstracts of the 37th Interscience Conference on Antimicrobial Agents and Chemotherapy.
1997
188
American Society for Microbiology
Washington D.C
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