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Azithromycin in bronchiolitis obliterans complicating bone marrow transplantation: a preliminary study.

Bronchiolitis obliterans (BO) is a serious noninfectious pulmonary complication following allogeneic bone marrow transplantation (BMT). Azithromycin, a macrolide antibiotic, may have a beneficial effect in BO through its anti-inflammatory effect. The aim of the current study was to investigate the potential effect of azithromycin on pulmonary function tests (PFTs) in BO complicating BMT. PFTs of 153 post-BMT patients were followed; eight patients out of 153 (12%) developed obstructive airway disease on their PFTs, along with characteristic findings of BO on high-resolution computed tomography of the chest. These patients were given azithromycin 500 mg q.d. for 3 days, followed by 250 mg three times a week for 12 weeks. Clinically significant improvements were achieved both in forced vital capacity, where the mean (95% confidence interval) increase reported was 410 mL (0.16-0.65), which was an average improvement of 21.57%, and in the forced expiratory volume in one second, where the mean increase noticed was 280 mL (0.10-0.44), which was an average improvement of 20.58%. In conclusion, the potential role of azithromycin in the treatment of bronchiolitis obliterans is intriguing and it warrants further testing.

Adolescent↗

Triangular test applied to the clinical trial of azithromycin against relapses in Plasmodium vivax infections.

BACKGROUND: Sequential analysis enables repeated statistical analyses to be performed throughout a trial recruitment period, while maintaining a pre-specified power and type I error. Thus the trial can be stopped as soon as the information accumulated is considered sufficient to reach a conclusion. Sequential tests are easy to use and their statistical properties are especially suitable to trials with very straightforward objectives such as non-comparative phase II trials. We report on a phase II study based on the triangular test (TT) aiming at assessing the effectiveness of azithromycin in preventing Plasmodium vivax relapses. METHODS: To test whether the P. vivax relapse rate was either <12% or >or= 45% in patients treated with azithromycin, a sequential analysis based on the TT was as used. Patients infected with P. vivax were treated with azithromycin, 1.2 g daily, for 7 days. The onset of a relapse infection was monitored. RESULTS: Five patients presenting with an acute P. vivax infection were included in the study. All the patients were initially cured. Three patients reported mild gastrointestinal adverse effects. When the third patient relapsed, the sample path crossed the upper boundary of the TT, and the trial was stopped. CONCLUSIONS: Using the triangular test, with only a small number of patients, we concluded that azithromycin was not effective enough in preventing P. vivax relapses to warrant further evaluation in phase III. It is suggested that a wider use of sequential analysis in phase II anti-infective drugs trials may have financial and ethical benefits.

Adolescent↗

In-vitro activity of polymyxin B in combination with imipenem, rifampicin and azithromycin versus multidrug resistant strains of Acinetobacter baumannii producing OXA-23 carbapenemases.

BACKGROUND: Acinetobacter baumannii has emerged as a major nosocomial pathogen worldwide. Many of the circulating strains exhibit multi-drug resistance remaining consistently susceptible only to polymyxins. In-vitro studies have reported that polymyxins combined with carbapenems, rifampicin or azithromycin are synergistic against these strains despite in-vitro resistance to these agents alone. The use of antimicrobial combinations have therefore been advocated for the treatment of severe A. baumannii infection in man. In order to determine whether such combinations are synergistic against the prevalent clones of multi-drug resistant A. baumannii causing infection in the UK, we performed synergy testing against representative isolates using two rapid Etest methods. METHODS: The activity of polymyxin in combination with imipenem, azithromycin or rifampicin was assessed against five strains of multi-drug resistant A. baumannii encoding OXA-23 carbapenemases. Synergy studies were performed by Etest-agar dilution and a combined Etest strip method. Synergy was defined as a FICI of < or = 0.5. RESULTS: All strains were resistant to beta-lactams, carbapenems, quinolones and aminoglycosides but susceptible to polymyxins. Marked synergy was not seen with polymyxin in combination with imipenem, rifampicin or azithromycin against any of the strains. Borderline synergy (FICI = 0.5) was seen against one strain belonging to OXA-23 clonal group 2, using the Etest-agar dilution method only. CONCLUSION: In-vitro synergy with polymxyin in combination with imipenem, rifampicin or azithromycin is highly strain and method dependent. As reliable synergy could not be demonstrated against the prevalent UK multi-drug resistant strains, use of such combinations should not be used for empirical treatment of these infections in the UK. The optimal treatment for serious multi-drug A. baumannii infection and the role of combination therapy should be addressed in a prospective clinical trial.

Acinetobacter baumannii↗

Efficacy of azithromycin 1g single dose in the management of uncomplicated gonorrhoea.

This paper describes the efficacy of azithromycin 1g single dose in the management of uncomplicated gonorrhoea either with or without chlamydial co-infection. Three hundred and one patients were treated for gonorrhoea between January 2000 and June 2001; 226/301 (75.1%) were treated with azithromycin 1g stat dose while the rest were treated with different regimens. Ninety-seven of 301 (32.2%) of all isolated strains were found to be resistant to at least one antibiotic where penicillin constituted the majority (23%). Chlamydial co-infection was found in 38.2% (115/301). Only 73.1% (220/301) attended for a test-of-cure, all but six patients had negative gonorrhoea cultures at their reviews. Among the six failures 3/32 (9.3%) were initially on amoxicillin, 2/170 (1.2%) on azithromycin and 1/22 (4.5%) on ciprofloxacin. Hence, azithromycin stat dose has proved to be a cost-effective treatment for uncomplicated gonorrhoea supported by the increased prevalence of penicillin-resistant organisms, concomitant chlamydial infection and the high failure rate in keeping review appointments.

Adolescent↗

Single-dose azithromycin for the treatment of children with acute otitis media.

Azithromycin is an azalide with in vitro activity against otitis media pathogens, good middle ear penetration and a prolonged half-life. A total of four clinical trials have evaluated the clinical success rate, safety and compliance of single-dose azithromycin (30 mg/kg) in the treatment of children with otitis media. Among all the patients treated with single-dose azithromycin (30 mg/kg), and presented previously in four published clinical trials, end-of-treatment clinical success was 88% (544 out of 619) and maintained clinical success at the end-of-study was 82% (498 out of 610). Three of the four studies included a mandatory baseline tympanocentesis. The overall end-of-treatment and end-of-study clinical success rates among all culture-positive patients was 84% (222 out of 263) and 80% (210 out of 263), respectively. Per pathogen end-of-treatment clinical success rates observed were 91% (125 out of 137) among patients with Streptococcus pneumoniae, 77% (75 out of 97) among patients with Haemophilus influenzae, 100% (14 out of 14) among patients with Moraxella catarrhalis, 64% (seven out of 11) among patients with baseline Streptococcus pyogenes and 25% (one out of four) among patients with a S. pneumoniae and H. influenzae mixed infection. Clinical success was observed in 90% (106 out of 118) of patients with baseline macrolide-susceptible S. pneumoniae and in 67% (14 out of 21) among patients with baseline macrolide-resistant S. pneumoniae (p = 0.01). Adverse events were uncommon, mostly mild and transitory gastrointestinal complaints, and in the two larger comparative trials, were less frequent than the rates observed with the comparator agents. Compliance was excellent (99-100%). Single-dose azithromycin (30 mg/kg) represents an alternative for the treatment of pediatric patients with uncomplicated acute otitis media, particularly in those geographic regions where high-level S. pneumoniae macrolide resistance is uncommon, and for those patients that require directly observed therapy or when compliance may be a problem.

Acute Disease↗

Comparison of the serum and intracellular pharmacokinetics of azithromycin in healthy and diabetic volunteers.

STUDY OBJECTIVE: To compare serum and intracellular pharmacokinetics of azithromycin in healthy volunteers and patients with diabetes. DESIGN: Open-label, parallel study. SETTING: Clinical research center. SUBJECTS: Twelve patients with diabetes and 12 healthy volunteers. INTERVENTIONS: Subjects were given a single 500-mg dose of azithromycin followed by 250 mg/day for 2 days. Blood samples were obtained just before and after the third dose for up to 24 hours for serum and 168 hours for intracellular measurement of azithromycin. MEASUREMENTS AND MAIN RESULTS: Pharmacokinetic parameters were calculated by noncompartmental methods and compared with a t test. The groups did not differ in maximum concentration, time to maximum concentration, or area under the concentration-time curve in serum or polymorphonuclear cells (PMNs). Differences in the PMN:serum ratio were observed at the 24-hour time point (healthy 1209 +/- 432, diabetic 859 +/- 286, p=0.051). CONCLUSION: In general, the pharmacokinetics of azithromycin are comparable in diabetics and healthy volunteers. Accumulation of drug in macrophages was slightly lower in patients.

Adult↗

Life-threatening bradyarrhythmia after massive azithromycin overdose.

9-month-old infant was inadvertently administered azithromycin 50 mg/kg, taken from floor stock, instead of the prescribed ceftriaxone. Shortly thereafter, she became unresponsive and pulseless. The initial heart rhythm observed when cardiopulmonary resuscitation was started was a widecomplex bradycardia, with a prolonged rate-corrected QT interval and complete heart block. The baby was resuscitated with epinephrine and atropine, but she suffered severe anoxic encephalopathy. Torsade de pointes and QT-interval prolongation have been reported after administration of macrolide antibiotics, including azithromycin, both intravenously and orally. This has occurred especially in the context of coadministered drugs that inhibit the cytochrome P450 (CYP) 3A4 isoenzyme, such as ketoconazole and astemizole. However, bradycardia with complete heart block has not, to our knowledge, been reported specifically with intravenous administration of azithromycin alone, either with therapeutic doses or overdose. Clinicians should be alerted about the potential of azithromycin to cause life-threatening bradycardia, and pharmacy systems should be implemented to ensure special care in the safe administration of this drug, especially when dispensed from a point-of-care source.

Anti-Bacterial Agents↗

Retrospective comparison of azithromycin, clarithromycin, and erythromycin for the treatment of foals with Rhodococcus equi pneumonia.

The objective of this retrospective study was to compare the efficacy of azithromycin-rifampin, clarithromycin-rifampin, and erythromycin-rifampin for the treatment of pneumonia caused by Rhodococcus equi in foals. Eighty-one foals with naturally acquired pneumonia caused by R. equi were included in the study. Information on age, sex, breed, physical examination findings, laboratory testing, and thoracic radiography was abstracted from each medical record. Foals were divided in 3 groups based on the antimicrobial agent selected for therapy. Short-term (discharge from the hospital) and long-term (apparently healthy as a yearling) success rates, days of hospitalization, days with fever, days with tachypnea, and percentage of radiographic improvement were compared among groups. Foals treated with clarithromycin-rifampin had significantly (P = .02) higher odds of overall short-term (odds ratio [OR] = 12.2) and long-term (OR = 20.6) treatment success and significantly fewer days with fever than foals treated with erythromycin-rifampin. Foals treated with clarithromycin-rifampin had a significantly (P = .03) higher percentage of radiographic improvement and a tendency (P = .06) toward higher odds of overall short-term (OR = 8.1) and long-term (OR = 11.8) treatment success compared to foals treated with azithromycin-rifampin. Among foals with severe radiographic lesions, the success rates of foals treated with clarithromycin-rifampin both short-term (88%) and long-term (83%) were significantly (P = .02) higher than that of foals treated with azithromycin-rifampin (0%). For each treatment group, the only reported adverse effect was diarrhea that was mild and self-limiting in most cases. The combination clarithromycin-rifampin is superior to azithromycin-rifampin or erythromycin-rifampin for the treatment of pneumonia caused by R. equi in foals in a referral population.

Actinomycetales Infections↗

Concentrations of erythromycin and azithromycin in mature Chinook salmon Oncorhynchus tshawytscha after intraperitoneal injection, and in their progeny.

A single dose (40 mg kg(-1)) of erythromycin or azithromycin dihydrate was injected intraperitoneally into maturing female fall Chinook salmon 12 to 32 d before spawning to observe the distribution, retention and clearance of the drugs in plasma, kidney, coelomic fluid and egg vitellin, and their persistence in alevins derived from these fish. Salmon administered prophylactic dosages of erythromycin as subadults were also included to investigate potential interactive effects of oral and injected treatments on reproductive performance and antibiotic clearance. Erythromycin was rapidly cleared from plasma and coelomic fluid, but was detected in the kidney (3.52 to 12.40 microg g(-1)) and egg vitellin (5.32 to 8.87 microg ml(-1)) of all fish at spawning. High, stable concentrations of azithromycin were detected in plasma (14.66 to 20.33 microg ml(-1)), kidney (43.16 to 59.96 microg g(-1)), coelomic fluid (2.52 to 5.50 microg ml(-1)) and egg vitellin (12.65 to 23.51 microg ml(-1)). Oral administration of erythromycin to subadult salmon did not significantly affect tissue concentrations of either erythromycin or azithromycin administered by prespawning injection. Reductions in the percentage of eggs that yielded live embryos at the eyed stage of development occurred among eggs derived from females that had received orally administered erythromycin as subadults. Erythromycin was not detected in unfed fry derived from adults injected with the drug prespawning, but azithromycin was present for more than 2 mo after the onset of exogenous feeding.

Analysis of Variance↗

The role of azithromycin and clarithromycin in clinical practice.

BACKGROUND: Azithromycin and clarithromycin are the newest approved macrolide antibiotics. OBJECTIVE: To review the pharmacology, microbiology, and clinical utility of these agents. SUMMARY: These agents have distinct advantages over erythromycin, including an improved pharmacokinetic profile, less toxicity, and a wider spectrum of activity. They are approved for the treatment of respiratory tract infections and uncomplicated skin and skin-structure infections associated with specific organisms. Azithromycin is also indicated for the treatment of nongonococcal urethritis. In addition, these agents may be useful in the treatment of toxoplasmosis, mycobacterial disease, Lyme disease, and legionellosis. Clarithromycin and azithromycin have lower rates of gastrointestinal side effects than erythromycin. CONCLUSIONS: Although clarithromycin and azithromycin show promise in the treatment of some less common infections, they should be considered alternatives to conventional agents in the treatment of respiratory tract, skin, and skin-structure infections caused by the usual pathogens. The expense of these agents may be prohibitive for routine use.

Animals↗

An open label comparative study of azithromycin and doxycycline in the treatment of non-gonococcal urethritis in males and Chlamydia trachomatis cervicitis in female sex workers in an STD clinic in Singapore.

AIM OF STUDY: The aim of this study was to compare the clinical and microbiological efficacy of a single 1 gram dose of azithromycin against 1 week of doxycycline at 100 mg twice a day in the treatment of: (1) uncomplicated non-gonococcal urethritis (NGU) in male patients, and (2) culture proven Chlamydia trachomatis cervicitis in female sex workers. METHOD: The subjects were 53 male patients who attended the clinic and were diagnosed to have non gonococcal urethritis based on clinical symptoms and a urethral smear, and 63 female sex workers, who had both a positive enzyme immunoassay (EIA) test and Chlamydia trachomatis cultures. Follow-up visits were made at one and two weeks post-treatment to assess efficacy, subsequent relapse and presence of side effects. The male patients were also assessed at four weeks post treatment to determine default and reinfection rates. RESULTS: Both azithromycin (clinical cure rates 62.5% at one week, 86.4% at two weeks in male patients; 96.6% at two weeks in female sex workers) and doxycycline (clinical cure rates 65.4% at one week, 90.9% at two weeks in male patients; 100% at two weeks in female sex workers) were effective in treating non-gonococcal urethritis and chlamydial cervicitis. Both drugs were very effective in eradicating proven Chlamydia trachomatis infections, with success in 100% of cases of Chlamydia trachomatis NGU in males, and 96.6% and 100% cure rates, for azithromycin and doxycycline respectively, in female sex workers with cervicitis. There were no statistically significant differences between the two drugs in terms of clinical efficacy, influence on default rates or subsequent risk of reinfection. CONCLUSIONS: We conclude that a single dose of azithromycin is as effective as a one week course of doxycycline in treating non-gonococcal urethritis in males and in the elimination of Chlamydia trachomatis in females with cervicitis, with the added advantage of a convenient single dose that can be supervised.

Adolescent↗

[Pharmacovigilance study of azithromycin tablets (500 mg) in the treatment of adult patients with respiratory tract infections].

Our aim was to study a new form of azithromycin (500 mg tablets) in order to evaluate the tolerability and the influence of the ingestion of food on tolerability, the efficacy and treatment compliance in a large number of patients with respiratory tract infections. We carried out an open, non-comparative, multicenter, observational and prospective pharmacovigilance study of 3223 outpatients with respiratory tract infections randomly assigned to receive a daily dose of azithromycin for three months taken either during or outside meals. Patients were evaluated during an initial visit and two later ones in order to record the adverse events and establish the clinical efficacy. The diagnostics were as follows: pharyngotonsillitis (1200), acute otitis media (394), acute bronchitis (1134), exacerbation of chronic bronchitis (436), and community-acquired pneumonia (53). The overall therapeutic efficacy was satisfactory (cure or improvement) in 96% to 97% at the second visit and in 93% to 94% in the third (pharyngotonsillitis, 93%; acute otitis media, 91%; acute bronchitis, 94%; exacerbation of chronic bronchitis, 94%; and community-acquired pneumonia, 96%). A total of 170 adverse events were reported in 141 patients (4.4%); 12 were severe yet not related to the study medication. Eighty-eight patients showed adverse events presumed to be related to azithromycin; most were in the digestive tract. No differences in tolerability were observed in relation to food intake. Treatment compliance was high (97%). The elevated clinical efficacy, adequate compliance and the excellent tolerability profile of azithromycin tablets make them a safe and effective alternative in the treatment of respiratory tract infections.

Adolescent↗

Chlamydial conjunctivitis in contact lens wearers: successful treatment with single dose azithromycin.

PURPOSE: To reveal clinical presentations of chlamydial conjunctivitis in contact lens wearers as well as to evaluate the clinical and microbiological efficacy of oral azithromycin in the treatment of this condition. METHODS: Twenty contact lens users with chlamydial conjunctivitis were included in this retrospective study. Chlamydial infection was diagnosed by isolation of Chlamydia trachomatis in cell culture of conjunctival scrapings. All patients were treated with a single 1 g oral dose of azithromycin. Follow-up clinical and microbiological examinations were performed 1 month after treatment. RESULTS: All patients suffered from some ocular symptoms such as itching, burning, tearing, and nonspecific irritation, but none had apparent conjunctival injection or any conjunctival discharge. The majority (90%) had bilateral complaints. Mild follicular reaction, limited to the lateral part of lower fornices, was present in 17 patients; the remaining patients had normal biomicroscopical findings. Four weeks following the single azithromycin dose, C. trachomatiswas eradicated in all patients and 17 (85%) were free of symptoms. CONCLUSION: Chlamydial infection should be considered more frequently in differential diagnosis of symptomatic contact lens wearers. Azithromycin is the most promising agent for the treatment of chlamydial conjunctivitis due to its excellent bacteriological efficacy and very convenient single dose administration.

Adolescent↗

In-vitro antimalarial activity of azithromycin against chloroquine sensitive and chloroquine resistant Plasmodium falciparum.

BACKGROUND: [corrected] The spread of drug resistance in Plasmodium falciparum has made the situation essential to look into new effective therapeutic agents like antibiotics. Azithromycin is a potential, chemotherapeutic agent which possesses antimalarial activity and favourable pharmacokinetic properties. It is an azalide microbiocide derived semi-synthetically from macrolide erythromycin. Like other antibiotics, the azalide azithromycin has ability to inhibit protein synthesis on 70S ribosomes. SETTINGS: Experimental study. SUBJECTS AND METHODS: The parasiticidal profile was studied in five chloroquine sensitive and five chloroquine resistant P. falciparum isolates obtained from various places of India. The antimalarial activity was evaluated in P. falciparum schizont maturation by short term culture for 24 hours and by exposing the parasites to the drug for 96 hours. Parasites synchronized at ring stage were put for culture with various concentrations of azithromycin dihydrate (0.01-40 micro/ml). RESULTS: At highest concentration (40 micro/ml), parasite growth was inhibited totally in all 10 isolates. Antimalarial activity at 96 hours was greater than at 24 hours in both chloroquine sensitive and resistant parasites, which may indicate that the inhibition of parasite growth may occur at clinically achievable concentration of the drug when parasites were exposed for several asexual cycles. CONCLUSION: Azithromycin shows a potential for eventual use alone or in combination in the treatment of chloroquine sensitive and resistant P. falciparum malaria.

Animals↗

[Summary of the clinical studies with azithromycin in the pediatric fields].

The clinical studies with azithromycin fine granules and capsules were conducted during the period from March 1993 to October 1994. Cmax's in 16 patients who received 10 mg/kg fine granules, were 0.29 +/- 0.24 microgram/ml, T1/2's were 42.0 +/- 11.8 hours, and AUC 0 approximately infinity's were 10.72 +/- 5.00 micrograms.hr/ml. The clinical results for azithromycin fine granule and capsules 10 mg/kg once daily for 3 days are as follows. The efficacy rate of fine granules, combining both "Excellent" and "Good", for pneumoniae where causative pathogenes were identified, was 95.3%, and for those which had failed to respond to previous chemotherapies, was 94.6%, respectively. The efficacy rate of capsules for 3 to 5 days was 100% in 40 cases where causative pathogenes were identified. Adverse reactions were found in 2.5%(fine granules) and in 5.4%(capsules) in cases eligible for evaluation. Abnormal changes in laboratory test were as follows: decrease of WBC by 5.6%(fine granules) and 9.3%(capsules) and increase in eosinophils by 7.1%(fine granules) and 11.4% (capsules). 59.8% of the patients claimed that the azithromycin 10% fine granules product was "easy to take". The result of a questionnaire on parents' demand on the improvement of antibiotics, showed that most concern was on the drug frequency(preferably once or twice daily) and the drug administering period(preferably short: 3 days). With regard to the efficacy, safety and compliance, it can be concluded that Azithromycin is one of the useful therapeutic regimens in the treatment of pediatric infections.

Azithromycin↗

Azithromycin--spectrum of activity, pharmacokinetics, and clinical applications.

Azithromycin is an azalide antimicrobial agent. Structurally related to the macrolide antibiotic erythromycin, its mechanism of activity (similar to erythromycin) is interference with bacterial protein synthesis by binding to the 50S component of the 70S ribosomal subunit. Although slightly less potent than erythromycin against gram-positive organisms, azithromycin demonstrates superior activity in vitro against a wide variety of gram-negative bacilli, including Haemophilus influenzae. Absorption is approximately 37% after a 500-mg oral dose. The large volume of distribution (23 L/kg) and low peak serum level (0.4 micrograms/ml) are consistent with data demonstrating extensive tissue distribution and intracellular accumulation. Metabolism is predominantly hepatic (to inactive metabolites), with biliary excretion a major pathway of elimination. Drug elimination is biphasic, with a terminal half-life of up to 5 days. Published trials have examined the efficacy and safety of azithromycin in the treatment of adults with upper and lower respiratory tract infections, skin and skin structure infections, streptococcal pharyngitis, and sexually transmitted diseases. Many used a 5-day course of 250 mg once daily, supplemented with a 250-mg dose on the first day of therapy. Selected trials in sexually transmitted diseases examined single 1-g doses. Promising results also were obtained with oral daily doses of 500 mg in patients with human immunoviral infection who also had Mycobacterium avium complex infection and in animals with toxoplasmosis. Adverse reactions are primarily gastrointestinal (nausea, diarrhea, abdominal pain), with minimal laboratory abnormalities reported. Gastrointestinal tolerance is better than that of erythromycin. Drug interactions have not been observed to date, although coadministration of azithromycin with a large meal may reduce absorption by up to 50%.

Azithromycin↗

Disk diffusion sensitivity testing and antibacterial activity of azithromycin.

Azithromycin (CAS 83905-01-5) disks with the selected loading (10, 15, 20 micrograms) were used for determination of the most suitable azithromycin disk concentration. Estimation was carried out by means of the regression line related to the zone size inhibition. Testing was performed on a variety of freshly isolated gram-positive, gram-negative and anaerobic bacteria derived from various specimens collected from patients. Using the disk diffusion method with 10 micrograms of azithromycin per disk in total 431 gram-positive, 875 gram-negative bacterial strains and 59 anaerobic bacteria were analysed. It was concluded that azithromycin disk containing 10 micrograms is sufficient for determination of bacterial sensitivity.

Anti-Bacterial Agents↗

Azithromycin pharmacokinetics and penetration to lymph.

The study of pharmacokinetics of azithromycin and penetration to peripheral human lymph was carried out in 14 healthy male volunteers taking 1 g orally after overnight fasting. Samples were analyzed by microbiological assay. The mean peak concentrations were 0.82 +/- 0.23 mg/l after 1.7 +/- 0.5 h in serum and 0.22 +/- 0.07 mg/l after 3.1 h in lymph. Nine of the 14 subjects showed a second and lower serum peak indicating the existence of enterohepatic circulation. The total areas under the serum concentrations curves (AUCs) till infinity were 7.9 +/- 3.1 mg. h/l compared to 4.4 +/- 1.2 mg.h/l in lymph. The mean lymph AUC was 68.1 +/- 20.7% of the serum AUC indicating a penetration ratio of 0.68. However, the actual amounts penetrating the tissues were much higher than this ratio suggests. Thus, after 6 h 81% of the drug was within the tissue compartment and after 120 h, 63% of the azithromycin was still present in the tissue compartment. The urinary recovery of azithromycin was 14.7 +/- 7.7% during the first 48 h. The serum curves and lymph curves displayed a distinctly slower phase of elimination after 12 h. The mean serum half-life was 5.4 +/- 3.4 h during the first 12 h (after the peak), whereas the value was 44.2 +/- 10.1 h during the interval 12-120 h. The corresponding half-life values for the peripheral lymph were 5.4 +/- 2.2 h and 50.8 +/- 11.6 h. Azithromycin possesses key pharmacokinetic properties that are prerequisites for a convenient once-daily dosage schedule which may improve patient compliance.

Adult↗