Penetration of amphotericin B in human lung tissue after single liposomal amphotericin B (AmBisome) infusion.

The distribution of amphotericin B in lung tissue was studied in 18 patients with primary or secondary lung cancer who underwent thoracotomy and pulmonary resection. At different times before surgery the patients were treated with liposomal amphotericin B 1.5 mg/kg by i.v. infusion over 1h. Blood and lung tissue samples were collected during surgery (one subject for each collecting time) and assayed for amphotericin B levels by HPLC. Due to surgical requirements, it was possible to obtain data from the 10th to the 25th h after the end of infusion. Plasma amphotericin B concentrations progressively decreased from 3.4 microg/ml at the 10th h to 1 microg/ml at the 25th h after the end of intravenous infusion. In lung tissue samples the lowest amphotericin B concentration (about 1 microg/g) was observed at the 10th h, then a progressive increase was observed with the highest value (2.5 microg/g) determined at the 25th h.

Effect of multiple doses of clarithromycin and amoxicillin on IL-6, IFNgamma and IL-10 plasma levels in patients with community acquired pneumonia.

Inflammation is crucial for the pathogenesis of both infectious and chronic obstructive pulmonary diseases. It is therefore important to modulate pulmonary inflammation in patients with these lung disorders. Macrolide antibiotics modulate inflammation in vitro and in in vivo by inhibiting the production of proinflammatory cytokines and prostaglandin E2, neutrophil chemotactic activity and elastase activity. This study evaluates the effect of clarithromycin (500 mg b.i.d. x 7 days) in comparison to amoxicillin (1 g t.i.d. x 7 days) in patients with community acquired pneumonia by testing plasma levels of IL-6, IFNgamma and IL-10 before starting therapy and at the 3rd and 7th days of therapy. Clarithromycin significantly decreased plasma levels of IL-6 and significantly increased those of IFNgamma and IL-10 at the 3rd and 7th day in comparison to basal levels. In patients treated with amoxicillin a significant decrease in IL-6 plasma levels was observed at the 7th day of therapy, probably in relation to the resolution of inflammatory symptoms. In the same patients IFNgamma plasma levels decreased during treatment while IL-10 plasma levels were unaffected.

Redox balance in patients with Down's syndrome before and after dietary supplementation with alpha-lipoic acid and L-cysteine.

The aim of the present study was to investigate the possible normalizing effect of antioxidants on certain parameters indicative of oxidative stress in Down's syndrome (DS). The study was performed in pediatric patients with DS with proven redox imbalance, who were advised to take a dietary supplementation composed of alpha-lipoic acid and L-cysteine for several treatment cycles (one treatment cycle = 30 days dietary supplementation plus 30 days wash-out). Serum thiol groups, serum total and septic reactive oxygen species (ROS) and total antioxidant status of serum were determined before and after dietary supplementation, using commercially available kits. In all the evaluable patients (n = 20), after 3.8 +/- 1.1 treatment cycles, thiol group serum concentrations and total antioxidant status of serum significantly increased (p < 0.0001 for both parameters) in comparison with basal values, while serum total and septic ROS significantly decreased (p < 0.0001 for both parameters). On the basis of these results it is impossible to demonstrate the clinical effects of the biochemical normalization obtained in patients with DS after supplying alpha-lipoic acid and L-cysteine. These data suggest that delaying the clinical expression of redox imbalance in patients with DS might be feasible by normalizing their redox balance.

In vitro comparative dynamics of modified-release clarithromycin and of azithromycin.

Antibacterial kinetics of modified-release clarithromycin (CLA) and azithromycin (AZI) against respiratory tract pathogens were compared in relation to their pharmacokinetic profile. The study was carried out in three strains of Streptococcus pneumoniae, group A beta-hemolytic Streptococcus pyogenes, Moraxella catarrhalis and Haemophilus influenzae, respectively, exposed to concentration gradients of CLA and AZI simulating human serum pharmacokinetics after administration of 500 mg p.o. in a single dose. Bactericidal kinetics were assessed by counting the number of survivors before each change in concentration over a period of 36 h. The minimal inhibitory concentrations (MICs) of CLA and AZI were evaluated at time 0 and after 36 h of exposure to antibiotics in the surviving organisms. The results showed that CLA and AZI, in the experimental conditions adopted, had different antibacterial kinetics. Moreover, the addition of the 14-OH metabolite of CLA at the same concentrations reached in human serum exerted a bactericidal effect against two strains of H. influenzae resistant to CLA and AZI. An increase in MICs was observed against S. pyogenes and H. influenzae, with higher values for AZI.

Interpretation of middle ear fluid concentrations of antibiotics: comparison between ceftibuten, cefixime and azithromycin.

AIMS: The aim of this study was to determine the potential influence of variables such as the cell content in the fluid, and serum levels, on the concentrations of ceftibuten, cefixime and azithromycin in the middle ear fluid of patients suffering from acute otitis media. METHODS: This randomized, open study compared the penetration of ceftibuten (9 mg kg(-1) 18 patients), cefixime (8 mg kg(-1), 16 patients) and azithromycin (10 mg kg(-1) 16 patients) into the intracellular and extracellular compartments of middle ear fluid of 50 paediatric patients (aged 8-14 years) with acute otitis media. Middle ear fluid was extracted by tympanocentesis 4, 12 and 24 h after dosing and divided into two fractions: with cells (as collected) (C+) and cell-free (C-). Antibiotics were assayed in C+ and C- samples by h.p.l.c. RESULTS: Ceftibuten achieved greater penetration into middle ear fluid than cefixime and azithromycin. Higher concentrations of ceftibuten (CTB) and cefixime (CFX) were found in the C- fraction (CTB: 4h 13.3+/-1.86; 12h 4.7+/-1.18; 24h 0.5+/-0.2. CFX: 4h 3.2+/-1.4; 12h 1.5+/-0.5; 24h>(0.1 mgl(-1)) than in the C+ fraction (CTB:4 h 8.4+/-4.3; 12 h 2.88+/-1.19; 24 h 0.3+/-0.27. CFX: 4 h 1.2+/-0.6; 12 h 0.8+/-0.2; 24 h>0.1 mg l(-1)) at the each time point, while the opposite was true for azithromycin (C-: 4 h 0.11+/-0.04; 12 h 0.12+/-0.08; 24 h 0.23+/-0.12. C+: 4 h 0.38+/-0.24; 12 h 0.9+/-0.03; 24 h 1.05+/-0.3 mg l(-1)). CONCLUSIONS: This study demonstrates that the penetration of antibiotics into the middle ear fluid is influenced by its serum concentrations as well as by the cell content in the fluid. Ceftibuten achieved higher middle ear fluid concentrations than cefixime in C+ and C- fractions at all time points. Both ceftibuten and cefixime concentrations are negatively influenced by the cell content in the fluid. In contrast the concentration of azithromycin to the middle ear fluid is positively influenced by the cell content in the fluid.

Melatonin involvement in immunity and cancer.

The most studied endocrine product of the pineal gland, melatonin, has been reported to be involved in the feedback between neuroendocrine and immune functions and to exert oncostatic action, at least in certain experimental conditions. Melatonin seems to be an integral part of the immune system, by exerting direct and/or indirect stimulatory effects on both cellular and humoral immunity. Likewise, an antitumor activity of melatonin has been shown in several experimental models in vivo and in vitro. The means by which melatonin exerts its effects on immunity and neoplastic growth have not been elucidated. The different putative mechanisms of action of melatonin investigated so far are here briefly discussed.

Melatonin involvement in immunity and cancer

The most studied endocrine product of the pineal gland, melatonin, has been reported to be involved in the feedback between neuroendocrine and immune functions and to exert oncostatic action, at least in certain experimental conditions. Melatonin seems to be an integral part of the immune system, by exerting direct and/or indirect stimulatory effects on both cellular and humoral immunity. Likewise, an antitumor activity of melatonin has been shown in several experimental models in vivo and in vitro. The means by which melatonin exerts its effects on immunity and neoplastic growth have not been elucidated. The different putative mechanisms of action of melatonin investigated so far are here briefly discussed.

Influence of protein binding on the pharmacodynamics of ceftazidime or ceftriaxone against gram-positive and gram-negative bacteria in an in vitro infection model.

The antibacterial activity of ceftriaxone and ceftazidime against Gram-positive and Gram-negative bacteria, clinically isolated from patients hospitalized in intensive care unit, was compared in vitro. The study was performed using a dynamic model in which the human kinetics of the drugs after i.m. administration were simulated. The antibacterial activity was tested by determining viable colony forming units (CFU) of bacteria/ml. Kill curves were constructed by plotting the log CFU/ml versus time. Simultaneously with CFU detection, ceftriaxone and ceftazidime concentrations were assayed by HPLC. The results obtained show that ceftriaxone and ceftazidime exert the same killing activity against the highly sensitive strains tested. Against the less sensitive strains, both drugs have initial good killing activity followed by bacterial regrowth using ceftriaxone while no regrowth was observed using ceftazidime. These data indicate that both ceftazidime and ceftriaxone exhibit primarily time-dependent bacterial killing. Moreover, only unbound drug appears to be effective, so only free drug should be considered in the pharmacokinetic-pharmacodynamic interaction.

Optimum treatment of streptococcal pharyngitis.

Streptococcal pharyngitis is a common infection in children and adolescents. The great majority of these infections are caused by group A beta-haemolytic streptococci. Although the use of penicillins for group A beta-haemolytic streptococcal pharyngitis has reduced the incidence of rheumatic fever, in the past decade several studies of pharyngitis treatment have reported penicillin failure. It has also been suggested that in comparison with the penicillins the cephalosporins are associated with a lower rate of clinical failure. Cephalosporins have drawbacks in cost, administration frequency or adverse effect profile. Moreover, there is the theoretical risk of cross-antigenicity to cephalosporins in penicillin-allergic patients. Erythromycin is a traditional alternative to penicillins, especially in penicillin-allergic patients, for the treatment of tonsillopharyngitis. However, increased resistance as well as failure rates as high as 24.7% have been reported for erythromycin in the treatment of pharyngitis. Therefore oral penicillins, and alternatively oral cephalosporins, should be considered first-line agents for the treatment of culture-confirmed group A beta-haemolytic streptococcal tonsillopharyngitis. Cephalosporins are useful especially for the treatment of recurrent streptococcal tonsillopharyngitis.

Ceftibuten concentrations in human tonsillar tissue.

In a study designed to determine ceftibuten concentrations in tonsillar tissue, subjects scheduled to undergo tonsillectomy were administered 400 mg of ceftibuten in a single oral dose. Between 2 and 24 h after the dose was given, tonsillar tissue samples were taken during surgery and assayed for ceftibuten. Mean concentrations in tonsillar tissue 4.4 h and 24.6 h after the 400 mg dose were 5.3 +/- 2.7 and 0.3 +/- mg/g, respectively. Concurrent mean serum concentrations were 7.42 +/- 1.66 and 0.15 +/- 0.13 mg/ml, respectively. The apparent half-life of drug in the tissue was 5.3 h. The presence of high ceftibuten concentrations in tonsillar tissue suggests that a once-daily regimen may be effective in treating tonsillitis and pharyngitis.

Concentrations of ceftibuten in bronchial secretions.

Ceftibuten is a broad-spectrum oral cephalosporin exhibiting antimicrobial activity against a wide range of gram-negative and some gram-positive pathogens. Pharmacokinetic studies have shown that the molecule has an oral bioavailability higher than 90% of the administered dose (reaching peak serum concentrations of 5-19 mg/l after a single dose of 200 and 400 mg). Moreover, ceftibuten has been shown to be useful in the treatment of acute lower respiratory tract infections. This study was performed to determine the distribution of ceftibuten in bronchial secretions from patients affected by the exacerbation of chronic bronchitis. Patients were treated with a single 400-mg oral dose of ceftibuten. Blood and bronchial-secretion samples were obtained just before, and at 0.5, 1, 2, 4, 8, 12, 16 and 24 h after dosing. Cells were separated from bronchial secretions by centrifugation. Ceftibuten in duplicate samples of both serum and bronchial secretion was quantified by HPLC. Ceftibuten reached peak levels 2 and 4 h after oral administration in serum and in bronchial secretions, respectively (18.12 +/- 2.13 and 9.19 +/- 3.1 mg/l, respectively). Falling curves after the peaks showed a monoexponential decay. The absorption was very rapid both in serum and bronchial secretions, but elimination was slower in bronchial secretions than in serum.

Bactericidal kinetics of an in vitro infection model of once-daily ceftriaxone plus amikacin against gram-positive and gram-negative bacteria.

The in vitro efficacy of ceftriaxone plus amikacin combination against gram-positive and gram-negative bacteria, clinically isolated from patients affected by pneumonia in intensive care units, was compared to that of the 2 drugs used alone. The study was performed using a dynamic model in which the human kinetics of the drugs after intramuscular administration was simulated. The antibacterial activity was tested by determining the bacterial cell count (CFU/ml). Killing curves came out from plotting the log CFU/ml versus time. In the same way, ceftriaxone and amikacin concentrations were assayed by HPLC and fluorescence polarization immunoassay, respectively. The results show that ceftriaxone plus amikacin combination exert a high killing activity against all tested strains. The two antibiotics alone initially have a good killing activity but this is followed by bacterial regrowth for all tested isolates. This data supports the results of several clinical studies which have shown a good therapeutic efficacy of ceftriaxone plus amikacin combination in the treatment of severe infections caused by organisms intermediately sensitive to these drugs.

Efficacy and tolerability of brodimoprim od versus norfloxacin bid in the treatment of bacterial urinary tract infections.

The efficacy and tolerability of brodimoprim OD versus norfloxacin BID were studied in patients affected by bacterial urinary tract infections. The study was performed in 203 patients divided into two parallel randomized groups orally given either brodimoprim 400 mg OD on the first day followed by 200 mg OD for 2 days, or norfloxacin 400 mg BID respectively. The efficacy of treatment was evaluated by the bacterial cultures, tolerability, analysis of signs and symptoms, a complete physical examination and from laboratory data. The results showed that brodimoprim and norfloxacin in the majority of patients resulted in a reduction of fever and symptoms caused by the infective process. Of the 103 patients enrolled in the brodimoprim OD group, 99 had a complete course of therapy with a positive outcome. There was only one case of failed treatment and 3 cases which could not be evaluated because of voluntary interruption of treatment. Of the 100 patients treated with norfloxacin BID, 94 completed therapy with a positive clinical outcome and there were 4 cases of treatment failure. Thus the efficacy of brodimoprim OD appears comparable to that of norfloxacin BID in the treatment of urinary tract infections.

Modulation of melatonin secretion by acetyl-L-carnitine in adult and old rats.

Modification of melatonin synthesis and release by acetyl-L-carnitine (ALC) was studied in adult (2 month old) and old (24-month-old) male Sprague Dawley rats. When ALC was injected at 1500 into adult rats at doses of 10, 30, or 90 mg/kg, there was a remarkable increase in their pineal and serum melatonin 1 hr later. However, using the same experimental protocol acute ALC administration in old rats did not modify pineal and serum melatonin levels. ALC administered in the same dose range induced a significant increase in pineal and serum melatonin in adult rats treated at 0100 h following exposure of 30 min to bright, white light to suppress endogenous melatonin. In the same conditions, in old rats, only the higher dose (90 mg/kg) caused any noteworthy increase in melatonin pineal content while lower doses were uneffective both on serum and pineal melatonin levels. It is known that ALC affects fatty acid transport in the cells, modulates CoA, modifies neuronal transmission and reduces lipofuscin accumulation which is related to lipid peroxidation. The action of ALC on melatonin synthesis could be the result of a modulation of the neuronal transmission related to circadian pineal endocrine activity. Moreover, since both ALC and melatonin exert remarkable scavenger activity, it is possible to suppose that ALC effects in reversing certain aging processing may be due to its ability to promote melatonin production.

Effect of antibiotics on Bordetella pertussis adhering activity: hypothesis regarding mechanism of action.

Microbial adherence to epithelial cell surfaces has been implicated as the first step in the initiation of several infectious diseases. The ability of antibiotics to affect the properties of bacterial adherence to cell surfaces may be a criterion in selecting antibiotics for therapy. This study was performed in order to investigate the activity of amoxicillin, chloramphenicol, and clarithromycin in modifying the adhering activity of Bordetella pertussis to human epithelial cells. The actions of antibiotics, alone or combined with aprotinin, were compared with that of trypsin, aprotinin and trypsin+aprotinin, to investigate the chemical nature of the ligand where antibiotics could act. The adhering activity was evaluated on human epithelial cells, collected from the oral mucosa, challenged with B. pertussis A2963 previously incubated in the presence of the tested substances for 1 h at 37 degrees C in a shaker incubator. After staining, the percentage of mucosal cells with more than 50 adhering bacteria was evaluated. Under the described experimental conditions, trypsin significantly reduced the adherence of B. pertussis. Aprotinin had no effect but was able to counteract the inhibitory action of trypsin. Both clarithromycin and chloramphenicol markedly reduced adhering activity and their actions were not counteracted by aprotinin. Amoxicillin was without effect. It was hypothesized that chloramphenicol and clarithromycin, exerting their antimicrobial action by inhibiting bacterial protein synthesis, affected bacterial adhesion through an unknown mechanism without proteolytic effect.

Fosfomycin distribution in the lower urinary tract after administration of fosfomycin trometamol salt.

Fosfomycin trometamol (FT) is a new fosfomycin salt with pharmacokinetic characteristics allowing hypothesis of its use in the single-dose therapy of lower urinary tract infections. In this study the diffusion of fosfomycin into bladder mucosa and urine after administration of a single oral dose of FT (3 g) was evaluated in patients affected by bladder or prostatic carcinoma having to undergo surgery. The administration of FT was scheduled in order to obtain blood, urine and tissue samples, to be collected during surgical operation at different times post administration. The peak concentrations in serum and bladder mucosa were detected within 3 h and 6 h respectively. Fosfomycin concentrations in bladder mucosa proved to be higher than the MICs of the most common urinary tract pathogens for at least 36 h. In urine, fosfomycin reached concentrations markedly higher than those found in serum and bladder mucosa, antibacterial levels lasting until the 48th hour post dosing. Fosfomycin trometamol, because of its pharmacokinetic and pharmacodynamic properties, appears to be suitable for single-dose therapy of uncomplicated UTIs.

Brodimoprim concentrations in bronchial mucosa, bronchial secretions and middle ear effusions.

Brodimoprim, a structural analogue of trimethoprim, is a long acting broad spectrum antibacterial agent characterized by a good pharmacokinetic profile, allowing once daily (OD) administration. The aim of this study was to investigate the penetration of brodimoprim into bronchial mucosa, bronchial secretion and middle ear effusion, in order to evaluate the efficacy of the antibiotic in respiratory tract infections. The study was performed in patients affected by chronic bronchitis having to undergo diagnostic bronchoscopy (n = 26), in patients affected by exacerbation of chronic bronchitis with purulent or mucopurulent secretions (n = 10), and in patients affected by otitis media with eardrum perforation (n = 28). Patients were orally treated with 400 mg of brodimoprim (single dose). Samples of serum, bronchial mucosa, bronchial secretion and middle ear effusion were collected in the separate series of patients above mentioned, at different times after drug administration. Brodimoprim determinations were performed by a microbiological method using Bacillus subtilis ATCC 6633 as test microorganism. Brodimoprim reached the highest concentration in serum 4 h after administration and was still detectable at 24th hour. In bronchial mucosa and in bronchial secretion the peaks were reached at 8th hour (9.7 +/- 5.3 mg/kg and 4.57 +/- 1 mg/l respectively) while in middle car effusion were reached at 4th hour (4.8 +/- 2.5 mg/l). The drug was still detectable at antibacterial concentrations, both in infected fluids and in tissue samples, 24 hours after administration (4.3 +/- 1.8 mg/kg in bronchial mucosa; 3.5 +/- 0.66 mg/l in bronchial secretions; 3 +/- 0.6 mg/l in middle ear effusion).(ABSTRACT TRUNCATED AT 250 WORDS)

A new model examining intracellular and extracellular activity of amoxicillin, azithromycin, and clarithromycin in infected cells.

An in vitro infection model was created using a suspension of macrophages, polymorphonuclear leukocytes, lymphocytes, fibroblasts, and human serum to which pathogen and antibiotic were added. Separate intracellular and extracellular antibiotic concentrations and activity against Staphylococcus aureus and Legionella pneumophila were assessed for three antimicrobial agents: amoxicillin, azithromycin and clarithromycin. Amoxicillin was found almost exclusively in extracellular fluid, where it was active; intracellularly, it was ineffective. Azithromycin, in contrast, was primarily concentrated and active intracellularly, with little activity in extracellular fluid. Clarithromycin was present in both compartments and possessed significant activity both intracellularly and extracellularly.

Clarithromycin clinical pharmacokinetics.

Clarithromycin is a semisynthetic macrolide antibiotic, structurally related to erythromycin. It has a more favourable pharmacokinetic profile than erythromycin, thus allowing twice-daily administration and possibly increasing compliance among outpatients. Clarithromycin is well absorbed from the gastrointestinal tract and its systemic bioavailability (about 55%) is reduced because of first-pass metabolism. It undergoes rapid biodegradation to produce the microbiologically active 14-hydroxy-(R)-metabolite. The maximum serum concentrations of clarithromycin and its 14-hydroxy metabolite, following single oral doses, are dose proportional and appear within 3 hours. With multiple doses, steady-state concentrations are attained after 5 doses and the maximal serum concentrations of clarithromycin and of the 14-hydroxy derivative appear within 2 hours after the last dose. Clarithromycin is well distributed throughout the body and achieves higher concentrations in tissues than in the blood. Also, the 14-hydroxy metabolite exhibits high tissue concentrations, with values about one-third of the parent compound concentrations. The presence of food appears to have no clinically significant effect on clarithromycin pharmacokinetics. The main metabolic pathways are oxidative N-demethylation and hydroxylation, which are saturable and result in nonlinear pharmacokinetics. The primary metabolite (14-hydroxy derivative) is mainly excreted in the urine with the parent compound. A reduction in urinary clearance in the elderly and in patients with renal impairment is associated with an increase in area under the plasma concentration-time curve, peak plasma concentrations and elimination half-life. Mild hepatic impairment does not significantly modify clarithromycin pharmacokinetics. In conclusion, clarithromycin, because of its antibacterial activity and pharmacokinetic properties, appears to be a useful alternative to other macrolides in the treatment of community acquired infections.