Serum and WBC pharmacokinetics of 1500 mg of azithromycin when given either as a single dose or over a 3 day period in healthy volunteers

Use of Azithromycin in Pregnancy: More Doubts than Certainties

Macrolides such as azithromycin are commonly prescribed antibiotics during pregnancy. The good oral bioavailability and transplacental transfer of azithromycin make this drug suitable for the treatment of sexually transmitted diseases, toxoplasmosis, and malaria. Moreover, azithromycin is useful both in the management of preterm pre-labor rupture of membranes and in the adjunctive prophylaxis for cesarean delivery. The aim of this comprehensive narrative review is to critically analyze and summarize the available literature on the main aspects of azithromycin use in pregnant women, with a special focus on adverse offspring outcomes associated with prenatal exposure to the drug. References for this review were identified through searches of MEDLINE, PubMed, and EMBASE. Fetal and neonatal outcomes following prenatal azithromycin exposure have been investigated in several studies, yielding conflicting results. Increased risks of spontaneous miscarriage, major congenital malformations, cardiovascular malformations, digestive system malformations, preterm birth, and low birth weight have been reported in some studies but not in others. Currently, there is no conclusive evidence to support that azithromycin use by pregnant women causes adverse outcomes in their offspring. Therefore, this agent should only be used during pregnancy when clinically indicated, if the benefits of treatment are expected to outweigh the potential risks.

Azithromycin concentrations during long-term regimen, a pilot study in patients with MALT lymphoma

In view of the antineoplastic effects of the macrolide clarithromycin in mucosa associated lymphatic tissue (MALT)-lymphoma, we performed a pilot study assessing levels of azithromycin in plasma, peripheral blood mononuclear cells (PBMC) and polymorphonuclear leukocytes (PMN) of MALT-lymphoma patients to determine the pharmacokinetics and potential influences of respective concentrations on the therapeutic outcome. In total 16 patients with MALT-lymphoma received 1.5 g of oral azithromycin once-weekly over 6 months. Blood was sampled directly prior to the following dose every 4 weeks during treatment. Drug levels were analysed by high performance liquid chromatography in plasma and intracellularly in PBMC and PMN. They were correlated with patients’ age, weight and body-mass-index and compared between patients responsive or unresponsive to treatment. Mean azithromycin plasma levels of all patients were 58.97 ± 30.48 ng/ml, remaining stable throughout the treatment period. Correlation analysis of plasma azithromycin showed no significance. Intracellular PBMC concentrations were 6648 ± 8479 ng/ml, without any significant difference between responders and non-responders. Mean PMN levels were 39,274 ± 25,659 ng/ml and significantly higher in patients unresponsive to treatment (t = 2.858, p = 0.017). Our drug regime led to continuously high plasma and exceedingly high intracellular concentrations of azithromycin in PBMC and PMN. Age, weight or body-mass-index had no significant influence on plasma levels and thence should not be considered in dosage finding. High AZM levels in PBMC did not lead to a better treatment response, whereas enrichment in PMN suggested a poorer outcome. The threshold for immunomodulatory effects on lymphoma cells might not have been reached. Additionally, the finding of stable plasma and intracellular concentrations over months with high-dose azithromycin administered in intervals might also be important for the further design of azithromycin-based trials against MALT-lymphoma.

Trial registration: EudraCT 2016-001521-13, 14/06/2016.

Effect of Once-Weekly Azithromycin vs Placebo in Children With HIV-Associated Chronic Lung Disease: The BREATHE Randomized Clinical Trial

IMPORTANCE

HIV-associated chronic lung disease (HCLD) in children is associated with small airways disease, is common despite antiretroviral therapy (ART), and is associated with substantial morbidity. Azithromycin has antibiotic and immunomodulatory activity and may be effective in treating HCLD through reducing respiratory tract infections and inflammation.

OBJECTIVE

To determine whether prophylactic azithromycin is effective in preventing worsening of lung function and in reducing acute respiratory exacerbations (AREs) in children with HCLD taking ART.

DESIGN, SETTING, AND PARTICIPANTS

This double-blind, placebo-controlled, randomized clinical trial (BREATHE) was conducted between 2016 and 2019, including 12 months of follow-up, at outpatient HIV clinics in 2 public sector hospitals in Malawi and Zimbabwe. Participants were randomized 1:1 to intervention or placebo, and participants and study personnel were blinded to treatment allocation. Participants included children aged 6 to 19 years with perinatally acquired HIV and HCLD (defined as forced expiratory volume in 1 second [FEV1] z score < -1) who were taking ART for 6 months or longer. Data analysis was performed from September 2019 to April 2020.

INTERVENTION

Once-weekly oral azithromycin with weight-based dosing, for 48 weeks.

MAIN OUTCOMES AND MEASURES

All outcomes were prespecified. The primary outcome was the mean difference in FEV1 z score using intention-to-treat analysis for participants seen at end line. Secondary outcomes included AREs, all-cause hospitalizations, mortality, and weight-for-age z score.

RESULTS

A total of 347 individuals (median [interquartile range] age, 15.3 [12.7-17.7] years; 177 boys [51.0%]) were randomized, 174 to the azithromycin group and 173 to the placebo group; 162 participants in the azithromycin group and 146 placebo group participants had a primary outcome available and were analyzed. The mean difference in FEV1 z score was 0.06 (95% CI, -0.10 to 0.21; P = .48) higher in the azithromycin group than in the placebo group, a nonsignificant difference. The rate of AREs was 12.1 events per 100 person-years in the azithromycin group and 24.7 events per 100 person-years in the placebo groups (hazard ratio, 0.50; 95% CI, 0.27 to 0.93; P = .03). The hospitalization rate was 1.3 events per 100 person-years in the azithromycin group and 7.1 events per 100 person-years in the placebo groups, but the difference was not significant (hazard ratio, 0.24; 95% CI, 0.06 to 1.07; P = .06). Three deaths occurred, all in the placebo group. The mean weight-for-age z score was 0.03 (95% CI, -0.08 to 0.14; P = .56) higher in the azithromycin group than in the placebo group, although the difference was not significant. There were no drug-related severe adverse events.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial specifically addressing childhood HCLD, once-weekly azithromycin did not improve lung function or growth but was associated with reduced AREs; the number of hospitalizations was also lower in the azithromycin group but the difference was not significant. Future research should identify patient groups who would benefit most from this intervention and optimum treatment length, to maximize benefits while reducing the risk of antimicrobial resistance.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02426112.

Can endolysosomal deacidification and inhibition of autophagy prevent severe COVID-19?

The possibility is examined that immunomodulatory pharmacotherapy may be clinically useful in managing the pandemic coronavirus disease 2019 (COVID-19), known to result from infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a positive-sense single-stranded RNA virus. The dominant route of cell entry of the coronavirus is via phagocytosis, with ensconcement in endosomes thereafter proceeding via the endosomal pathway, involving transfer from early (EEs) to late endosomes (LEs) and ultimately into lysosomes via endolysosomal fusion. EE to LE transportation is a rate-limiting step for coronaviruses. Hence inhibition or dysregulation of endosomal trafficking could potentially inhibit SARS-CoV-2 replication. Furthermore, the acidic luminal pH of the endolysosomal system is critical for the activity of numerous pH-sensitive hydrolytic enzymes. Golgi sub-compartments and Golgi-derived secretory vesicles also depend on being mildly acidic for optimal function and structure. Activation of endosomal toll-like receptors by viral RNA can upregulate inflammatory mediators and contribute to a systemic inflammatory cytokine storm, associated with a worsened clinical outcome in COVID-19. Such endosomal toll-like receptors could be inhibited by the use of pharmacological agents which increase endosomal pH, thereby reducing the activity of acid-dependent endosomal proteases required for their activity and/or assembly, leading to suppression of antigen-presenting cell activity, decreased autoantibody secretion, decreased nuclear factor-kappa B activity and decreased pro-inflammatory cytokine production. It is also noteworthy that SARS-CoV-2 inhibits autophagy, predisposing infected cells to apoptosis. It is therefore also suggested that further pharmacological inhibition of autophagy might encourage the apoptotic clearance of SARS-CoV-2-infected cells.

Antibiotics Utilization for Community Acquired Pneumonia in a Community Hospital Emergency Department

BACKGROUND

A local health authority in Canada implemented its own Antimicrobial Stewardship Program (ASP) which provide guidelines to clinicians to utilize when treating infectious diseases such as community-acquired pneumonia (CAP). Objectives: The primary objective is to describe antibiotic usage patterns at the community hospital's emergency department (ED) and to analyze the patterns in relation to ASP goals of reducing risk of infections, adverse drug events and antibiotic resistance, and to identify potential areas of improvement.

METHODS

This retrospective chart review included 156 adult patients with a diagnosis of CAP admitted to a community hospital ED from December 1, 2015 to November 30, 2016.

RESULTS

50.6% patients were prescribed moxifloxacin across all severity of CAP patients. Low and moderate severity CAP patients were most often prescribed antibiotic duration > 7 days. In low, moderate and high severity CAP patients who were treated using ceftriaxone, 100%, 88.9% and 66.6% patients were treated with ceftriaxone 2000 mg daily respectively.

CONCLUSIONS

Antibiotic prescribing patterns suggest fluoroquinolones were frequently being over-prescribed, ceftriaxone dosages were often too high, and duration of antibiotics for low and moderate severity CAP were too long. More efforts are needed to promote appropriate antibiotic usage and optimize patient care.

A Randomized Open-Label Evaluation of the Antimalarial Prophylactic Efficacy of Azithromycin-Piperaquine versus Sulfadoxine-Pyrimethamine in Pregnant Papua New Guinean Women

Emerging malaria parasite sulfadoxine-pyrimethamine (SP) resistance has prompted assessment of alternatives for intermittent preventive treatment in pregnancy (IPTp). The objective was to evaluate the tolerability and prophylactic efficacy of azithromycin (AZ) plus piperaquine (PQ) in pregnant women in Papua New Guinea. The study was an open-label, randomized, parallel-group trial. A total of 122 women (median gestation, 26 weeks [range, 14 to 32 weeks]) were randomized 1:1 to three daily doses of 1 g AZ plus 960 mg PQ tetraphosphate or single-dose SP (4,500 mg sulfadoxine plus 225 mg pyrimethamine), based on computer-generated block randomization. Tolerability was assessed to day 7, and efficacy was assessed to day 42 (when participants were returned to usual care) and at delivery. Data for 119 participants (AZ-PQ, n = 61; SP, n = 58) were analyzed. Both regimens were well tolerated, but AZ-PQ was associated with more gastrointestinal side effects (31%) and dizziness (21%). Eight women (6.7%) were parasitemic at recruitment but all were aparasitemic by 72 h. There were no differences in blood smear positivity rates between AZ-PQ and SP up to day 42 (0% versus 5.2%; relative risk [RR], 0.14 [95% confidence interval [CI], 0.01 to 2.58] [P = 0.18]; absolute risk reduction [ARR], 5.2% [95% CI, -1.3 to 11.6%]) and at the time of delivery (0% versus 8.7%; RR, 0.11 [95% CI, 0.01 to 2.01] [P = 0.14]; ARR, 8.7% [95% CI, -0.2 to 17.6%]). Of 92 women who were monitored to parturition, 89 (97%) delivered healthy babies; there were 3 stillbirths (SP, n = 1; AZ-PQ, n = 2 [twins]). There was a higher live birth weight (mean ± standard deviation) in the AZ-PQ group (3.13 ± 0.42 versus 2.88 ± 0.55 kg [P = 0.016]; mean difference, 0.25 kg [95% CI, 0.02 to 0.48 kg]). AZ-PQ is a promising candidate for IPTp.

Safety, tolerability and pharmacokinetic properties of coadministered azithromycin and piperaquine in pregnant Papua New Guinean women

AIMS

The aim of the present study was to investigate the safety, tolerability and pharmacokinetics of coadministered azithromycin (AZI) and piperaquine (PQ) for treating malaria in pregnant Papua New Guinean women.

METHODS

Thirty pregnant women (median age 22 years; 16-32 weeks' gestation) were given three daily doses of 1 g AZI plus 960 mg PQ tetraphosphate with detailed monitoring/blood sampling over 42 days. Plasma AZI and PQ were assayed using liquid chromatography-mass spectrometry and high-performance liquid chromatography, respectively. Pharmacokinetic analysis was by population-based compartmental models.

RESULTS

The treatment was well tolerated. The median (interquartile range) increase in the rate-corrected electrocardiographic QT interval 4 h postdose [12 (6-26) ms(0) (.5) ] was similar to that found in previous studies of AZI given in pregnancy with other partner drugs. Six women with asymptomatic malaria cleared their parasitaemias within 72 h. Two apararasitaemic women developed late uncomplicated Plasmodium falciparum infections on Days 42 and 83. Compared with previous pregnancy studies, the area under the concentration-time curve (AUC0-∞ ) for PQ [38818 (24354-52299) μg h l(-1) ] was similar to published values but there was a 52% increase in relative bioavailability with each dose. The AUC0-∞ for AZI [46799 (43526-49462) μg h l(-1) ] was at least as high as reported for higher-dose regimens, suggesting saturable absorption and/or concentration-dependent tissue uptake and clearance from the central compartment.

CONCLUSIONS

AZI-PQ appears to be well tolerated and safe in pregnancy. Based on the present/other data, total AZI doses higher than 3 g for the treatment and prevention of malaria may be unnecessary in pregnant women, while clearance of parasitaemia could improve the relative bioavailability of PQ.

Azithromycin suppresses CD4(+) T-cell activation by direct modulation of mTOR activity

Advanced macrolides, such as azithromycin (AZM) or clarithromycin (CLM), are antibiotics with immunomodulatory properties. Here we have sought to evaluate their in vitro influence on the activation of CD4(+) T-cells. Isolated CD4(+) T-cells were stimulated with agonistic anti-CD3/anti-CD28 monoclonal antibodies in the presence of 0.6 mg/L, 2.5 mg/L, 10 mg/L or 40 mg/L AZM or CLM. Cell proliferation, cytokine level in supernatants and cell viability was assessed. Intracellular signaling pathways were evaluated using reporter cell lines, FACS analysis, immunoblotting and in vitro kinase assays. AZM inhibited cell proliferation rate and cytokine secretion of CD4(+) T-cells in a dose-dependent manner. Similarly, high concentrations of CLM (40 mg/L) also suppressed these T-cell functions. Analysis of molecular signaling pathways revealed that exposure to AZM reduced the phosphorylation of the S6 ribosomal protein, a downstream target of mTOR. This effect was also observed at 40 mg/L CLM. In vitro kinase studies using recombinant mTOR showed that AZM inhibited mTOR activity. In contrast to rapamycin, this inhibition was independent of FKBP12. We show for the first time that AZM and to a lesser extent CLM act as immunosuppressive agents on CD4(+) T-cells by inhibiting mTOR activity. Our results might have implications for the clinical use of macrolides.

Single-dose azithromycin for acute otitis media: a pharmacokinetic/pharmacodynamic rationale

The pharmacokinetic (PK) and pharmacodynamic (PD) properties of the azalide azithromycin distinguish it from other antibiotics. The PK profile of azithromycin features high tissue-to-serum ratios, including high concentrations in the middle ear, and a prolonged elimination half-life. These characteristics result from the accumulation of drug within cells and its subsequent slow, sustained release from cells and tissues into the bloodstream. The PD properties of azithromycin include bactericidal activity against key respiratory tract pathogens and a prolonged postantibiotic, or persistent, effect. In addition, white blood cells deliver the drug to infected foci, thereby enhancing local tissue concentrations and improving in vivo efficacy. Recent PK studies in mice suggest that a single, large dose of azithromycin achieves higher tissue concentrations than do multidose regimens. Other studies in animal infection models, in particular, a gerbil model of acute otitis media, have demonstrated improved bacterial eradication when azithromycin is administered as a single dose rather than divided over 2 or 3 days. Taken together, the results from these preclinical studies provide a PK/PD rationale for the use of single-dose azithromycin in the treatment of acute otitis media. Clinical data on the efficacy and safety of single-dose azithromycin for the treatment of acute otitis media in children are presented in 2 accompanying articles in this supplement.

A pilot study of single-dose azithromycin versus three-day azithromycin or single-dose ceftriaxone for uncomplicated acute otitis media in children

BACKGROUND

The pharmacokinetic profile of azithromycin supports its use as single-dose therapy for uncomplicated acute otitis media (AOM) in children.

OBJECTIVE

This study was designed to (1) compare the safety of single-dose oral azithromycin, 3 daily doses of oral azithromycin, and a single dose of intramuscular ceftriaxone for the treatment of uncomplicated AOM in children, and (2) provide preliminary efficacy data to support initiation of a larger, comparative trial of single-dose azithromycin for the treatment of uncomplicated acute otitis media in children.

METHODS

In this single-center pilot study, children with uncomplicated AOM were randomly assigned to receive single-dose oral azithromycin (30 mg/kg), 3-day oral azithromycin (10 mg/kg once daily), or single-dose intramuscular ceftriaxone (50 mg/kg). Tympanocentesis was performed before administration of the first dose, and clinical response was assessed on days 14-15 and 28-30.

RESULTS

Between September 1995 and May 1997, 198 children (mean age, 2.5 years) were enrolled. All of the patients were evaluable for the safety and clinical intent-to-treat (ITT) analyses, and 98 were evaluable for the microbiologic ITT analysis. On day 14-15, rates of clinical success (cure or improvement) for the 3 treatment groups were: 62/64 (97%) for single-dose azithromycin, 60/63 (95%) for 3-day azithromycin, and 61/62 (98%) for single-dose ceftriaxone. On day 28-30, the corresponding clinical success rates were 61/65 (94%), 61/66 (92%), and 62/64 (97%). For the 98 microbiologically evaluable patients, clinical success rates at day 14-15 were 28/30 (93%) for single-dose azithromycin, 31/35 (89%) for 3-day azithromycin, and 33/33 (100%) for single-dose ceftriaxone. On day 28-30, the corresponding clinical success rates were 27/30 (90%), 30/35 (86%), and 32/33 (97%). Treatment-related adverse event rates for single-dose azithromycin, 3-day azithromycin, and single-dose ceftriaxone were 10.6%, 9.1%, and 9.1%, respectively.

CONCLUSION

In this pilot study comparing single-dose azithromycin, 3-day azithromycin, and single-dose ceftriaxone for the treatment of uncomplicated AOM in children, no differences were detected among the 3 regimens.

Blood, tissue, and intracellular concentrations of azithromycin during and after end of therapy

Although azithromycin is extensively used in the treatment of respiratory tract infections as well as skin and skin-related infections, pharmacokinetics of azithromycin in extracellular space fluid of soft tissues, i.e., one of its therapeutic target sites, are not yet fully elucidated. In this study, azithromycin concentration-time profiles in extracellular space of muscle and subcutaneous adipose tissue, but also in plasma and white blood cells, were determined at days 1 and 3 of treatment as well as 2 and 7 days after the end of treatment. Of all compartments, azithromycin concentrations were highest in white blood cells, attesting for intracellular accumulation. However, azithromycin concentrations in both soft tissues were markedly lower than in plasma both during and after treatment. Calculation of the area under the concentration-time curve from 0 to 24 h (AUC(0-24))/MIC(90) ratios for selected pathogens suggests that azithromycin concentrations measured in the present study are subinhibitory at all time points in both soft tissues and at the large majority of observed time points in plasma. Hence, it might be speculated that azithromycin's clinical efficacy relies not only on elevated intracellular concentrations but possibly also on its known pleotropic effects, including immunomodulation and influence on bacterial virulence factors. However, prolonged subinhibitory azithromycin concentrations at the target site, as observed in the present study, might favor the emergence of bacterial resistance and should therefore be considered with concern. In conclusion, this study has added important information to the pharmacokinetic profile of the widely used antibiotic drug azithromycin and evidentiates the need for further research on its potential for induction of bacterial resistance.

Pharmacokinetics and ex vivo antimalarial activity of artesunate-azithromycin in healthy volunteers

In 18 male healthy subjects, artesunate (200 mg)-azithromycin (1,500 mg) daily for 3 days was found to be well tolerated, with only mild gastrointestinal disturbances reported. The pharmacokinetic properties of artesunate-azithromycin given in combination are comparable to those of the drugs given alone. Artesunate and its major active metabolite, dihydroartemisinin, are responsible for most of the ex vivo antimalarial activity, with a delayed contribution by azithromycin.

Pharmacokinetic properties of azithromycin in pregnancy

Azithromycin (AZI) is an azalide antibiotic with antimalarial activity that is considered safe in pregnancy. To assess its pharmacokinetic properties when administered as intermittent preventive treatment in pregnancy (IPTp), two 2-g doses were given 24 h apart to 31 pregnant and 29 age-matched nonpregnant Papua New Guinean women. All subjects also received single-dose sulfadoxine-pyrimethamine (SP) (1,500 mg or 75 mg) or chloroquine (450-mg base daily for 3 days). Blood samples were taken at 0, 1, 2, 3, 6, 12, 24, 32, 40, 48, and 72 h and on days 4, 5, 7, 10, and 14 for AZI assay by ultra-high-performance liquid chromatography-tandem mass spectrometry. The treatments were well tolerated. Using population pharmacokinetic modeling, a three-compartment model with zero-order followed by first-order absorption and no lag time provided the best fit. The areas under the plasma concentration-time curve (AUC(0-infinity)) (28.7 and 31.8 mg.h liter(-1) for pregnant and nonpregnant subjects, respectively) were consistent with the results of previous studies, but the estimated terminal elimination half-lives (78 and 77 h, respectively) were generally longer. The only significant relationship for a range of potential covariates, including malarial parasitemia, was with pregnancy, which accounted for an 86% increase in the volume of distribution of the central compartment relative to bioavailability without a significant change in the AUC(0-infinity). These data suggest that AZI can be combined with compounds with longer half-lives, such as SP, in combination IPTp without the need for dose adjustment.

Efficacy of clarithromycin against experimentally induced pneumonia caused by clarithromycin-resistant Haemophilus influenzae in mice

Clarithromycin is a 14-member lactone ring macrolide with potent activity against Haemophilus influenzae, including ampicillin-resistant strains. We evaluated the in vivo efficacy of clarithromycin at 40 mg/day and 100 mg/day for 3 days in the treatment of a murine model of pneumonia using a macrolide-resistant H. influenzae strain, which was also ampicillin resistant. The MIC of clarithromycin was 64 microg/ml. The viable bacterial counts in infected tissues after treatment with 100 mg clarithromycin/kg of body weight were lower than the counts obtained in control and 40-mg/kg clarithromycin-treated mice. The concentrations of macrophage inflammatory protein 2 (MIP-2) and interleukin 1beta (IL-1beta) in bronchoalveolar lavage fluid (BALF) samples from mice treated at both concentrations were lower than in the control group. Pathologically, following infection, clarithromycin-treated mice, particularly at a dose of 100 mg/kg, showed lower numbers of neutrophils in alveolar walls, and inflammatory changes had apparently improved, whereas large aggregates of inflammatory cells were observed within the alveoli of control mice. In addition, we demonstrated that clarithromycin has bacteriological effects against intracellular bacteria at levels below the MIC. Our results indicate that clarithromycin may be useful in vivo for macrolide-resistant H. influenzae, and this phenomenon may be related to the good penetration of clarithromycin into bronchoepithelial cells. We also believe that conventional drug susceptibility tests may not reflect the in vivo effects of clarithromycin.

Once-weekly azithromycin in cystic fibrosis with chronic Pseudomonas aeruginosa infection

BACKGROUND

Data on the effects of long-term treatment with azithromycin (AZM) on inflammatory markers in cystic fibrosis patients chronically infected with Pseudomonas aeruginosa are scarce. So far there is no pharmacokinetic and clinical data on once-weekly dosage of AZM in CF patients.

METHODS

In a randomised double-blind, placebo-controlled trial, patients received AZM or placebo 1 per week for 8 weeks (AZM dosage--20-29 kg: 500 mg, 30-39 kg: 750 mg, 40-49 kg: 1000 mg and > or = 50 kg: 1250 mg) after a course of intravenous antipseudomonal antibiotics. Pulmonary function tests, the serum markers LPS-binding protein (LBP), interleukin-8 (IL-8), CRP, P. aeruginosa alginate in sputum samples and quality of life scores were evaluated.

RESULTS

Thirty-eight patients (21 AZM/17 placebo) (mean age: 23.7 years; mean FEV(1): 62% of predicted) were recruited. After treatment (mean dose of 21.2 mg/kg body weight once a week) pulmonary function declined in both groups compared to baseline (i.e. after cessation of i.v. antibiotics). The AZM group was significantly better for mean changes in serum CRP (AZM: +0.9 mg/l, placebo: +21.6 mg/l, p=0.019), lipopolysaccharide binding protein in serum, LBP (AZM: +0.9 microg/ml, placebo: +7.0 microg/ml, p=0.015), serum interleukin-8 (AZM: -3.1 pg/ml, placebo: +2.9 pg/ml, p=0.001) and alginate in sputum (AZM: +85 microg/ml, placebo: +353 microg/ml, p=0.048). Quality of life was significantly better after AZM and there was no increase in treatment-related adverse events.

CONCLUSION

Once-weekly azithromycin ameliorated inflammatory reactions and improved quality of life. A decline of pulmonary function after cessation of i.v. antibiotics could not be prevented.

Quantitative determination of azithromycin in human plasma by ultra performance liquid chromatography–electrospray ionization mass spectrometry and its application in a pharmacokinetic study

A selective, rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the quantitative determination of azithromycin in human plasma and its application in a pharmacokinetic study. With roxithromycin as internal standard, sample pretreatment involved a one-step extraction with diethyl ether of 0.5 mL plasma. The analysis was carried out on an ACQUITY UPLC BEH C(18) column (50 mm x 2.1 mm, i.d., 1.7 microm) with gradient elution at flow rate of 0.35 mL/min. The mobile phase was 50 mM ammonium acetate and acetonitrile. The detection was performed on a triple-quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI). Linear calibration curves were obtained in the concentration range of 1-1000 ng/mL, with a lower limit of quantification of 1 ng/mL. The intra- and inter-day precision (RSD) values were below 15% and accuracy (RE) was -1.3% to 5.7% at all QC levels. The method was applicable to clinical pharmacokinetic study of azithromycin in healthy volunteers following oral administration.

Azithromycin and lower respiratory tract infections

Azithromycin is a macrolide antibiotic that has been structurally modified from erythromycin with an expanded spectrum of activity and improved tissue pharmacokinetic characteristics relative to erythromycin. This allows once-daily administration for 3-5 days of treatment compared with traditional multi dosing 7-10-day treatment regimens. It has been successfully employed in lower respiratory tract infections. Recent data indicate that azithromycin may exert anti-inflammatory/immunomodulatory effects that may be of use in the treatment of both acute and chronic airway diseases. This review examines the role of azithromycin in lower respiratory tract infections analysing published data on exacerbations of chronic bronchitis, community-acquired pneumonia and cystic fibrosis both in adults and children. In addition, pharmacokinetic and pharmacodynamic properties of the drug are also considered.

Pharmacokinetics and sputum penetration of azithromycin during once weekly dosing in cystic fibrosis patients

In this study we examined pharmacokinetics, systemic exposure and sputum penetration of azithromycin (AZM) in CF patients on chronic daily AZM therapy after changing to a once weekly dosing scheme. Eight adult CF patients using AZM 500 mg/day were changed to a once weekly dose of 1000 mg during 3 months. Once per month sputum and blood samples were collected. AZM was quantified in blood plasma and polymorphonuclear neutrophils. The cumulative weekly dose was reduced with a factor of 3.5 (7x500 mg vs. 1x1000 mg weekly). This led to a reduction in area under the curve (AUC+/-S.D.) with a factor of 2.5+/-0.8 in plasma, 2.8+/-0.9 in blood, 2.2+/-1.1 in PMNNs and to a reduction in average sputum concentration with a factor of 3.0 (+/-1.5). At 1000 mg once weekly reduced but still substantial concentrations were achieved in PMNNs and in sputum. Although not significant, a tendency towards less than linear reduction was found. In order to calculate and propose an optimal dosing scheme we need to establish a relation between exposure levels and clinical efficacy.

Comparative pharmacokinetics of azithromycin in serum and white blood cells of healthy subjects receiving a single-dose extended-release regimen versus a 3-day immediate-release regimen

The pharmacokinetic profiles of azithromycin given as a single-dose regimen (2.0-g extended-release microspheres) were characterized in serum and white blood cells (WBC) and compared with those of a 3-day regimen (a 500-mg immediate-release tablet once daily; total dose, 1.5 g) in an open-label, randomized, parallel-group study of 24 healthy adult subjects. Serial blood samples were collected up to 5 days after the start of dosing for both regimens. Safety assessments were conducted throughout the study. A single 2.0-g dose of azithromycin microspheres achieved significantly higher exposures in serum and WBC during the first 24 h after the start of dosing than a 3-day regimen: an approximately threefold higher area under the curve from time zero to 24 h postdose (AUC(0-24)) and an approximately twofold higher mean peak concentration on day 1. The single-dose regimen provided total azithromycin exposures in serum and WBC similar to those of the 3-day regimen, as evidenced by the similar AUC(0-120) and trough azithromycin concentrations in serum and WBC (mononuclear leukocytes [MNL] and polymorphonuclear leukocytes [PMNL]). For both regimens, the average total azithromycin exposures in MNL and PMNL were approximately 300- and 600-fold higher than those in serum. Azithromycin concentrations in MNL and PMNL remained above 10 microg/ml for at least 5 days after the start of dosing for both regimens. This "front-loading" of the dose on day 1 is safely achieved by the extended-release microsphere formulation, which maximizes the drug exposure at the time when the bacterial burden is likely to be highest.

Pharmacokinetics of azithromycin in plasma, blood, polymorphonuclear neutrophils and sputum during long-term therapy in patients with cystic fibrosis

Chronic therapy with the macrolide antibiotic azithromycin (AZM) is widely practiced in the treatment of patients with cystic fibrosis (CF) and chronic lung infection with Pseudomonas aeruginosa. Azithromycin dosage is variable, based on published studies, and not supported by pharmacokinetic data. This study describes the pharmacokinetics of the long-term administration of AZM (500 mg per day) in CF patients. AZM concentrations were quantified in the plasma, blood, isolated polymorphonuclear neutrophils (PMNNs), and sputum of 8 adult CF patients. The AZM distribution t1/2 was 0.1 hours in plasma. The (mean +/- standard deviation) elimination t(1/2) was 102 +/- 20 hours in plasma, 180 +/- 68 hours in blood, and 289 +/- 166 hours in PMNNs. The C(max) of AZM was 0.67 +/- 0.31 mg/L in plasma and 2.01 +/- 0.74 mg/L in blood, of which 1.44 +/- 0.69 mg/L was found in PMNNs. In sputum the concentration of AZM ranged from 12 to 53 mg/L and was still detectable at concentrations in the range 4 to 27 mg/L 10 days after the last dose. On average, the concentration in PMNNs was 2100 times the C(plasma) 24 hours after dosing AZM. These results confirm the accumulation of AZM in PMNNs. The authors conclude that sputum levels are elevated far above plasma and blood concentrations. The long t(1/2) in blood and PMNNs and the slow decrease in sputum levels indicate a less frequent dosing schedule (for instance once weekly) should be studied in future clinical trials of AZM in patients with cystic fibrosis.

Quantitative determination of azithromycin in human plasma by liquid chromatography–mass spectrometry and its application in a bioequivalence study

A sensitive, rapid liquid chromatographic-electrospray ionization mass spectrometric method for determination of azithromycin in human plasma was developed and validated. Azithromycin in plasma (0.2mL) was extracted with methyl tert-butyl ether-hexane (50:50, v/v), organic phase was transferred to another clear 1.5mL Eppendorf tube and evaporated to dryness at 40 degrees C and dissolved in mobile phase, samples were separated using a Thermo Hypersil HyPURITY C18 reversed-phase column (150mmx2.1mm i.d., 5microm), together with a mobile phase containing of 20mM ammonium acetate (pH 5.2)-acetonitrile-methanol (50:40:10, v/v/v) and was isocratically eluted at a flow rate of 0.2mL/min. Azithromycin and its internal standard, clarithromycin, were measured by electrospray ion source in positive selective ion monitoring mode. The method demonstrated that good linearity ranged from 2 to 1000ng/mL with r=0.9977. The limit of quantification for azithromycin in plasma was 2ng/mL with good accuracy and precision. The higher mean extraction recovery, say 81.2% and 75.5% for azithromycin and internal standard (IS), respectively, was obtained in this work. The intra-day and inter-day precision ranged from 4.8% to 8.6% and 6.4% to 10.7% (R.S.D.), respectively. The established method has been successfully applied to bioequivalence study of 2 azithromycin formulations for 24 healthy volunteers.

[Clinical trial of chemotherapy identified according to chemosensitivity assay for oral cancer patients with unresectable recurrent lesions]

Treatment of patients with unresectable recurrent oral cancer is quite difficult. In particular,there is no scientific evidence to select anti-cancer drugs for patients who were given previous radiation therapy. To select optional chemotherapy regimens, we have employed a new chemosensitivity testing method, a collagen gel droplet embedded culture sensitivity test (CD-DST) for patients with unresectable oral cancer. Six oral cancer patients with recurrence and/or metastatic disease were treated with the optional chemotherapy based on the results of CD-DST. No result was obtained due to a problem of poor growth of tumor cells in one case. In another case, we could not find a sensitive anti-cancer drug among the agents we examined. These 2 patients were treated with selected palliative pain control therapy. Optional chemotherapy based on the results of CD-DST was given to 4 patients showing sensitivity to the anti-cancer drugs examined. Tumor recession or tumor dormancy was observed clinically during a definite period. Toxicity was mild and the median survival was 10.9 months. We therefore conclude that the examination with CD-DST may provide important scientific evidence to determine a suitable chemotherapy for patients with advanced oral cancer.

Absolute bioavailability and intracellular pharmacokinetics of azithromycin in patients with cystic fibrosis

Chronic pulmonary infections with Pseudomonas aeruginosa are the primary cause of morbidity and mortality in patients with cystic fibrosis (CF). The macrolide antibiotics exhibit immunomodulatory and antivirulence activity. Clinical trials with azithromycin in CF have demonstrated significant improvements in pulmonary function and decreased hospitalizations. The purpose of this study was to compare the pharmacokinetics (PK) of azithromycin in patients with CF and controls. The study was conducted as an open-label, parallel, two-period crossover study involving 12 healthy volunteers and 12 patients with CF. Period 1 examined the serum PK following a single oral and intravenous dose, while period 2 examined the intracellular PK following multiple-dose oral administration. CF subjects differed significantly from controls based on weight (53.1 versus 71.0 kg; P < 0.01) and body mass index (19.7 versus 23.2; P < 0.01), respectively. Ninety-two percent of CF patients were pancreatic insufficient and were receiving pancreatic enzymes. The rate (time to reach maximum serum drug concentration, 3.0 versus 3.0 h; P = 0.78) and extent of absorption (absolute bioavailability, 34.2 versus 42.8%; P = 0.37) were similar in patients with CF and controls, respectively. Distribution to the tissues (rate of drug transfer from the central to the peripheral compartment, 1.22 versus 0.759 h(-1); P = 0.03) and elimination (rate of elimination from the central compartment, 0.693 versus 0.492 h(-1); P < 0.01) were more rapid in the healthy volunteers than in the CF subjects, respectively. Mononuclear cell concentrations (15.2 +/- 6.0 mg/liter) far exceeded the maximum serum drug concentration ( approximately 50-fold), demonstrating significant intracellular accumulation. These results indicate no alteration in dosage of azithromycin is necessary in patients with CF taking pancreatic enzymes.

Enhanced efficacy of single-dose versus multi-dose azithromycin regimens in preclinical infection models

OBJECTIVES

As a result of the prolonged half-life and unique pharmacokinetic and pharmacodynamic (PK-PD) characteristics of azithromycin, shorter dosing regimens are being evaluated for the treatment of community-acquired infections. To provide further support for a shorter dosing regimen, the efficacy of azithromycin was determined in preclinical infection models comparing single- versus multi-dose regimens.

METHODS

The efficacy of single versus multi-dose regimens of azithromycin was compared in mouse pneumonia, acute peritonitis, and neutropenic thigh infection models and in a gerbil model of Haemophilus influenzae acute otitis media. Azithromycin was administered as a single oral dose on the first treatment day, or as two divided doses over 2 treatment days, or as three divided doses over 3 treatment days. The pharmacokinetics of azithromycin was profiled following single and multi-dose regimens with the single dose data fit to an Emax model to characterize the PK-PD of azithromycin.

RESULTS

In the mouse efficacy models, administration of single-dose azithromycin produced superior rates of survival and bacterial clearance compared with the same total dose divided over 2 or 3 days. In the gerbil model, a single dose sterilized the middle ear and more rapidly cleared H. influenzae. The pharmacokinetic evaluation confirmed similar total exposure (AUC) in serum and pulmonary tissue for the three regimens. Correlation of PK-PD parameters and antimicrobial efficacy confirmed a concentration-dependent and dosing-independent relationship for azithromycin.

CONCLUSIONS

These data are consistent with data reported from clinical studies and indicate that a single-dose regimen would be at least as effective as the same dose administered over several days.

Azithromycin extraction from municipal wastewater and quantitation using liquid chromatography/mass spectrometry

Azithromycin is a broad spectrum antimicrobial agent that is approved in the United States for use in humans. Due to azithromycin's low rate of metabolism it is likely to be found in wastewater treatment plants, where its broad spectrum of antimicrobial activity could lead to development of resistance in bacteria. A liquid-liquid extraction using K2CO3 and methyl-t-butyl ether (MTBE) was used to extract azithromycin from 10 ml aliquots of wastewater. Liquid chromatography was performed using a Luna C18(2) (30 mm x 2.0 mm) column with a mass spectrometer friendly mobile phase containing 50:24:2:24 acetonitrile, methanol, tetrahydrofuran, and 0.04 M ammonium hydroxide. The mass spectrometer used an electrospray source with positive ionization and an ion trap detector. A linear standard curve from 5 to 200pg/ml was validated and used to quantitate azithromycin in wastewater.

[Pharmacokinetic/pharmacodynamic analysis of antibiotic therapy in dentistry and stomatology]

INTRODUCTION

This study evaluates the efficacy of various antimicrobial treatments for orofacial infections on the basis of pharmacokinetic/pharmacodynamic (PK/PD) criteria.

METHODS

A complete a literature search was undertaken to establish the MIC90 values of the five microorganisms most frequently isolated in odontogenic infections and the pharmacokinetic parameters of 13 antibiotics used in these infections. Pharmacokinetic simulations were then carried out with mean population parameters and efficacy indexes were calculated for the 47 treatment regimens analyzed. For drugs showing time-dependent antibacterial killing, the time above MIC (t > MIC) was calculated. For drugs with concentration-dependent bactericidal activity, the AUC/MIC was calculated.

RESULTS

Amoxicillin-clavulanic (500 mg/8 h or 1000 mg/12 h) and clindamycin (300 mg/6 h) in the time-dependent killing group and moxifloxacin (400 mg/24 h) in the concentration-dependent group showed adequate efficacy indexes against the five pathogens considered to be the most commonly implicated in odontogenic infections. The spiramycin plus metronidazole combination, present in the commercial formulation Rhodogyl, did not reach satisfactory PK/PD indexes.

CONCLUSION

PK/PD indexes, which are useful predictors of the potential efficacy of antibacterial therapy, were used with ontogenic infections in the present study. The PK/PD simulations showed that amoxicillin-clavulanic, clindamycin and moxifloxacin were the most suitable antibiotics for this kind of infection. Clinical trials are required to confirm that this methodology is useful in these pathologic processes.

Quantitative determination of azithromycin in plasma, blood and isolated neutrophils by liquid chromatography using pre-column derivatization with 9-fluorenylmethyloxycarbonyl-chloride and fluorescence detection

In this study, a high-performance liquid chromatographic method with pre-column derivatization and fluorescence detection was optimised and validated for the quantification of azithromycin (AZM) in plasma. Clarithromycin (CLM) was used as an internal standard. Pre-column derivatization was done with 9-fluorenylmethyloxycarbonyl-chloride. Recovery from blood and polymorphonuclear neutrophils (PMNNs) isolated by a gravity separation procedure was also assessed. Analytical separation was carried out using a C18 column as stationary phase and acetonitril-phosphatebuffer as mobile phase. Peak quantification was carried out by excitation at 26 7 nm and detection at 317 nm. A lower limit of quantitation of 0.042+/-0.017 mg/l in plasma, 0.119+/-0.065 mg/l in blood and 0.072+/-0.036 in water was achieved. Linearity was assessed from 0 to 1.5mg/l in plasma and blood and from 0-9 mg/l in water. The analytical method proved to be applicable in a pharmacokinetic study of AZM in a Cystic Fibrosis patient.

Pharmacokinetic/Pharmacodynamic Evaluation of Antimicrobial Treatments of Orofacial Odontogenic Infections

OBJECTIVE

To evaluate the efficacy of antimicrobial therapy in oral odontogenic infections using estimated pharmacokinetic/pharmacodynamic parameters or efficacy indices, and to compare pharmacokinetic/pharmacodynamic breakpoints with National Committee for Clinical Laboratory Standards' (NCCLS) breakpoints.

STUDY DESIGN

Retrospective literature search to obtain minimum inhibitory concentration (MIC) values, pharmacokinetic parameters of antimicrobials and NCCLS breakpoints. Pharmacokinetic simulations were carried out using WinNonlin software (Pharsight Corporation, Mountain View, CA, USA).

METHODS

For antimicrobials with time-dependent activity, the time that the plasma drug concentration exceeds the MIC as the percentage of dose interval at steady state was calculated. For antimicrobials with concentration-dependent activity, the total area under the plasma concentration-time curve over 24 hours at steady state divided by the MIC was calculated. Pharmacokinetic/pharmacodynamic breakpoints were calculated according to these parameters.

RESULTS

Only amoxicillin/clavulanic acid and clindamycin showed adequate efficacy indices against the most commonly isolated bacteria in odontogenic infections. Metronidazole reached good indices against anaerobes only. Pharmacokinetic/pharmacodynamic susceptibility breakpoints do not coincide exactly with NCCLS breakpoints.

CONCLUSION

Owing to the scarcity of double-blind, clinical trials on the use of antimicrobials in endodontics, this study may be useful in determining the best antimicrobial treatment in these infections. However, as we have not used concentration data in infected tissue to determine pharmacokinetic/pharmacodynamic indices, it would be necessary to design clinical trials in order to confirm these results.

Rationale for single and high dose treatment regimens with azithromycin

The rationale for the use of single dose and shorter course azithromycin treatment regimens is based on the pharmacokinetic properties of azithromycin. The drug has a long elimination half-life (>50 h), which enables short course 1- or 3-day dose regimens to be clinically effective. Azithromycin is concentrated within phagocytic cells and tissues and it achieves targeted delivery by these cells to sites of infection. In vitro and in vivo models have demonstrated that azithromycin is taken up, transported and released at the sites of infection by phagocytic cells such as polymorphonuclear neutrophils and macrophages. Uptake is not saturable; therefore delivery of the total dose of azithromycin as a 1- or 3-day regimen should lead to increased uptake and delivery of the drug to sites of infection.

Single-Dose Azithromycin for Respiratory Tract Infections

OBJECTIVE

To describe the pharmacology, efficacy, and safety data of the use of single-dose azithromycin for respiratory tract infections in children and adults.

DATA SOURCES

A MEDLINE search (1990–September 2003) was performed to identify all pertinent studies and review articles. When appropriate information was not available in the literature, data were obtained from the product manufacturers or abstracts from international conferences.

STUDY SELECTION AND DATA EXTRACTION

All available studies were reviewed to provide pharmacokinetic, pharmacodynamic, efficacy, and safety data on use of single-dose azithromycin for respiratory tract infections.

DATA SYNTHESIS

Several studies have demonstrated that shorter regimens of azithromycin (1500 mg over 3 day vs 5 day or single dose vs 3 day) provide higher serum exposures compared with the longer regimens. This makes it possible to give the same dose over a shorter period of time and achieve the same efficacy with the potential for enhanced adherence. Single-dose azithromycin 30 mg/kg was approved in 2003 for treatment of acute otitis media (AOM) in children. Studies have demonstrated that, when administering azithromycin as a single dose, its efficacy and safety are comparable to that of other standard regimens for AOM. Single-dose regimens for treatment of respiratory tract infections in adults have not been studied widely, with only 2 studies being conducted for treatment of community-acquired pneumonia and one study for treatment of tonsillitis; all demonstrated at least equal efficacy with the single-dose regimen compared with comparators given for longer periods of time.

CONCLUSION

Available data regarding single-dose azithromycin are promising. Although use of this regimen in children is warranted based on studies to date, additional large-scale trials are needed prior to mainstream use of the regimen in adults.

Azithromycin modulates neutrophil function and circulating inflammatory mediators in healthy human subjects

Effects on human neutrophils and circulating inflammatory mediators were studied in 12 volunteers who received azithromycin (500 mg/day, p.o.) for 3 days. Blood was taken 1 h before treatment, 2.5, 24 h and 28 days after the last dose. An initial neutrophil degranulating effect of azithromycin was reflected in rapid decreases in azurophilic granule enzyme activities in cells and corresponding increases in serum. The oxidative response to a particulate stimulus was also acutely enhanced. These actions were associated with high plasma and neutrophil drug concentrations. A continuous fall in chemokine and interleukin-6 serum concentrations, within the non-pathological range, accompanied a delayed down-regulation of the oxidative burst and an increase in apoptosis of neutrophils up to 28 days after the last azithromycin dose. Neutrophils isolated from blood at this time point still contained detectable drug concentrations. Acute neutrophil stimulation could facilitate antibacterial effects of azithromycin, while delayed, potentially anti-inflammatory activity may curtail deleterious inflammation.

Pharmacokinetics of azithromycin in foals after i.v. and oral dose and disposition into phagocytes

The properties of azithromycin suggest that it may be an alternative to erythromycin for treatment of Rhodococcus equi pneumonia in foals. To investigate this possibility, the disposition of azithromycin in plasma, polymorphonuclear leukocytes (PMN), and alveolar cells was examined after a single administration in foals. Azithromycin suspension was administered orally (p.o.) at a dose of 10 mg/kg to five healthy 2-3-month-old foals. Two weeks later, azithromycin for injection was administered by intravenous (i.v.) infusion at a dose of 5 mg/kg to the same foals. Plasma samples were collected after p.o. and i.v. administration. Peripheral blood PMN and bronchoalveolar lavage fluid and alveolar cells were collected after p.o. administration. Azithromycin concentrations were determined by reverse-phase high-performance liquid chromatography (HPLC) with coulometric electrochemical detection. Azithromycin p.o. absorption was variable with a mean systemic availability of 39% (+/-20%). The plasma half-life was 16 and 18.3 h after i.v. and p.o. administration, respectively. Azithromycin had a very large volume of distribution (V(d)) of 11.6 L/kg [V(d(ss))] and 12.4 L/kg [V(d(area))]. The large V(d) can be attributed to high tissue and intracellular concentrations, exhibited by the high concentration of azithromycin in PMN and alveolar cells. The PMN half-life was 49.2 h. Dosage of 10 mg/kg of azithromycin p.o. once daily for foals with R. equi pneumonia is recommended for further study.

Anti-inflammatory effects of macrolide antibiotics

Macrolides are widely used as antibacterial drugs. Clinical and experimental data, however, indicate that they also modulate inflammatory responses, both contributing to the treatment of infective diseases and opening new opportunities for the therapy of other inflammatory conditions. Considerable evidence, mainly from in vitro studies, suggests that leukocytes and neutrophils in particular, are important targets for modulatory effects of macrolides on host defense responses. This underlies the use of the 14-membered macrolide erythromycin for the therapy of diffuse panbronchiolitis. A variety of other inflammatory mediators and processes are also modulated by macrolides, suggesting that the therapeutic indications for these drugs may be extended significantly in future.