Drugs online research references
Antimicrob Agents Chemother. 1991 Jun;35(6):1024-8.
Prophylactic and therapeutic activities of azithromycin in a mouse model of pneumococcal pneumonia.
Azoulay-Dupuis E, Vallee E, Bedos JP, Muffat-Joly M, Pocidalo JJ.
Hopital Claude Bernard, Institut National de la Sante et de la Recherche Medicale U.13, Paris, France.
Azithromycin is a new acid-stable 15-membered-ring macrolide that exhibits an extended half-life and excellent tissue distribution, including distribution in the lung. We compared its in vivo activity with that of erythromycin using two models of Streptococcus pneumoniae pneumonia, namely, a model of acute infection in Swiss mice and a model of subacute infection in C57BL/6j mice. Female mice were infected by oral delivery into the trachea of 10(5) CFU of a virulent serotype 3 strain of S. pneumoniae (P 4241). Prophylactic and therapeutic treatments were given orally (p.o.) or subcutaneously (s.c.) by various regimens. In the model of subacute infection, a single dose of azithromycin, 25 mg/kg, given p.o. 7 h before infection protected 92% of the mice, while erythromycin was completely ineffective. In the model of acute infection, a single dose of azithromycin, 50 mg/kg, given s.c. 24 h prior to challenge protected 80% of the mice, whereas only 35% of the mice survived with erythromycin, 50 mg/kg, 1 h before challenge. Therapy, which was studied exclusively in the model of subacute infection, was initiated 48 h postinfection. Two doses of 12.5 mg/kg given p.o. 12 h apart resulted in 80% survival of mice treated with azithromycin versus 7% survival of mice treated with erythromycin. Pulmonary clearance of bacteria was consistent with the survival rates. Two doses (25 mg/kg) of azithromycin given s.c. at 48 and 65 h after infection led to complete clearance of bacteria from the lungs and blood, whereas erythromycin-treated mice remained bacteremic. The pharmacokinetics of azithromycin account for its superior efficacy against S. pneumoniae pneumonia relative to the efficacy of erythromycin.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1656849&dopt=Abstract
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Antimicrob Agents Chemother. 1991 Jun;35(6):1186-90.
Comparison of the effects of the new azalide antibiotic, azithromycin, and erythromycin estolate on rat liver cytochrome P-450.
Amacher DE, Schomaker SJ, Retsema JA.
Drug Safety Evaluation Department, Pfizer Central Research, Groton, Connecticut 06340.
Erythromycin and some other macrolide antibiotics can first induce a cytochrome P-450 isozyme similar to the one induced in rats by pregnenolone-16 alpha-carbonitrile and then inhibit it by forming a stable cytochrome P-450-metabolite complex. The purpose of this study was to compare azithromycin, a novel 15-membered ring azalide, and erythromycin estolate for the potential to cause hepatic microsomal enzyme induction and inhibition in Sprague-Dawley rats. The daily oral administration of 800 mg of erythromycin estolate per kg for 7 days resulted in statistically significant elevations of NADPH-cytochrome c reductase, erythromycin N-demethylase (3.2-fold), and total cytochrome P-450 content. Approximately 40% of cytochrome P-450 was complexed with erythromycin metabolite. In contrast, the daily administration of 200 mg of azithromycin per kg for 7 days caused significant elevations of N-demethylase (2.5-fold) only and did not produce any increases in total cytochrome P-450 content or NADPH-cytochrome c reductase. No complexed cytochrome P-450 was detected in the azithromycin-dosed rats despite liver concentrations of azithromycin that were 118 times greater than the liver concentrations of erythromycin estolate in erythromycin estolate-dosed rats. Although the short-term oral administration of azithromycin produced hepatic accumulation of the drug and elevated azithromycin demethylase activity, there was no other evidence of hepatic cytochrome P-450 induction or inactivation via cytochrome-metabolite complex formation. In contrast to erythromycin estolate, azithromycin is not expected to inhibit its own metabolism or that of other drugs via this pathway.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1656856&dopt=Abstract
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Antimicrob Agents Chemother. 1991 Jul;35(7):1356-9.
Activities of sparfloxacin, azithromycin, temafloxacin, and rifapentine compared with that of clarithromycin against multiplication of Mycobacterium avium complex within human macrophages.
Perronne C, Gikas A, Truffot-Pernot C, Grosset J, Vilde JL, Pocidalo JJ.
Institut National de la Sante et de la Recherche Medicale Unite 13, Hopital Claude Bernard, Paris, France.
The activities of sparfloxacin, azithromycin, temafloxacin, and rifapentine against two virulent strains of the Mycobacterium avium complex isolated from patients with AIDS were evaluated in a model of intracellular infection and were compared with that of clarithromycin. Human monocyte-derived macrophages were infected with the M. avium complex at day 6 of culture. The intracellular CFU was counted 60 min after inoculation. The intracellular and supernatant CFU was counted on days 4 and 7 after inoculation. The concentrations used, which were equal to peak levels in serum, were 10 micrograms of rifapentine per ml (MICs for the two strains, 4 and 16 micrograms/ml), 4 micrograms of clarithromycin per ml (MICs, 8 and 4 micrograms/ml), 1 microgram of azithromycin per ml (MICs, 32 and 16 micrograms/ml), 4 micrograms of temafloxacin per ml (MICs, 2 and 16 micrograms/ml), and 1 microgram of sparfloxacin per ml (MICs, 0.5 and 2 micrograms/ml). Compared with controls on day 7 after inoculation, clarithromycin (P less than 0.001), sparfloxacin (P less than 0.001), and azithromycin (P less than 0.001 for the first strain, P less than 0.02 for the second) slowed intracellular replication. Rifapentine (P less than 0.001) and temafloxacin (P less than 0.001) slowed intracellular replication of the first strain but not of the second strain. Azithromycin plus sparfloxacin was as effective as sparfloxacin alone. In this macrophage model, sparfloxacin or clarithromycin (difference not significant) exhibited a better efficacy than rifapentine, azithromycin, or temafloxacin against intracellular M. avium complex infection.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1656860&dopt=Abstract
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