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PubMed1996

Efficacy and safety of azithromycin versus phenoxymethylpenicillin in the treatment of acute maxillary sinusitis.

In the treatment of acute maxillary sinusitis, azithromycin offers an advantage over phenoxymethylpenicillin in that a complete course of treatment requires drug administration once daily for only three days. In this double-blind, parallel-group, multicenter study, 438 patients with radiographically verified maxillary sinusitis were randomly assigned to receive either 500 mg azithromycin once daily for three days (221 patients) or 1.3 g phenoxymethylpenicillin three times daily for ten days (217 patients). Nasal secretion, maxillary tenderness and pain, nasal obstruction, general malaise, and hyposmia, were assessed at the start of the study and on days 4, 11, and 25 of treatment. After 11 days 58% of the patients in the azithromycin group were cured versus 51% in the penicillin group; after 25 days the cure rate was 79% versus 76%, respectively. When both cure and improvement were considered, the corresponding figures after 11 days were 97% (azithromycin) and 95% (penicillin); after 25 days they were 92% and 88%, respectively. Adverse events, predominantly gastrointestinal, occurred in 73 (33%) of the azithromycin-treated patients and in 87 (40.1%) of those treated with penicillin. No difference in efficacy was found between the two drugs in the treatment of acute maxillary sinusitis, and the adverse effects were comparable. The short duration of treatment with azithromycin offers a significant advantage over treatment with phenoxymethylpenicillin.

Acute Disease↗
PubMedDate not supplied

Azithromycin versus penicillin V for the treatment of early Lyme borreliosis.

In a randomized multicenter therapeutic trial, 32 patients with erythema migrans received oral azithromycin 500 mg once daily and 33 patients received phenoxymethylpenicillin (penicillin V) 1 million U three times daily for 10 days. Follow-up was for a median of 17 (range 3-32) months. Four weeks after initiation of therapy, 20 (62%) patients given azithromycin and 17 (51%) patients given penicillin V were completely free of all signs and symptoms and did not develop new ones subsequently (no significant difference). Three months after initiation of therapy, the corresponding figures were 25 (78%) azithromycin and 28 (85%) penicillin V recipients (no significant difference). There were only minor sequelae such as arthralgia, headache, fatigue, stiff neck and dysesthesia. Azithromycin led to a significantly faster resolution of the erythema migrans than penicillin V (p < 0.001). Significantly more patients with more severe compared with mild initial disease had an elevated IgM antibody titer prior to therapy (p < 0.001). Usually mild to moderate side effects occurred in 12 patients given azithromycin and five patients given penicillin V (p < 0.05). Azithromycin appears to be as effective as penicillin V for the treatment of early Lyme borreliosis and it seems to clear the erythema migrans more promptly.

Adult↗
PubMedDate not supplied

Azithromycin and doxycycline for treatment of Borrelia culture-positive erythema migrans.

Adult patients with typical solitary erythema migrans, participating in prospective therapeutic studies on early Lyme borreliosis at the Lyme borreliosis Outpatient's Clinic, University Department of Infectious Diseases in Ljubljana, in 1991 to 1993, and followed up for 1 year, were included in the study. Only patients who were treated with azithromycin or doxycycline and in whom Borrelia burgdorferi was isolated from the border of the skin lesion prior to institution of antibiotic treatment were selected for presentation in this report. Fifty-eight patients received azithromycin (500 mg twice daily for the first day, followed by 500 mg once daily for 4 days) and 42 patients received doxycycline (100 mg twice daily for 14 days). The median duration of skin lesions after the beginning of treatment was 6.5 (2-30) days in the azithromycin group and 8 (2-35) days in the doxycycline group (non-significant difference). During the follow-up of 12 months one patient in each group developed major later manifestations of Lyme borreliosis and in 19 patients minor manifestations appeared: in nine (15.5%) treated with azithromycin and in ten (23.8%) receiving doxycycline. In one patient in the azithromycin group and in one patient in the doxycycline group B. burgdorferi was isolated from normal appearing skin at the site of previous erythema migrans 2 months after the institution of antibiotic therapy. Five (8.6%) patients receiving azithromycin and nine (21.4%) patients receiving doxycycline reported mild to moderate gastrointestinal discomfort. In addition, five patients treated with doxycycline developed photosensitivity.

Adult↗
PubMed1991

The activity of azithromycin in animal models of infection.

High and prolonged tissue levels accompanied by low serum concentrations are a feature of azithromycin, an azalide antibiotic. It has a broad spectrum of activity against gram-positive and gram-negative microorganisms and several intracellular pathogens. A number of animal models of localised infection have been developed which demonstrate that the efficacy of azithromycin correlates with its extravascular pharmacokinetics and not with blood levels. In many instances, because of high tissue bioavailability, azithromycin has better in vivo efficacy than comparative agents, despite a similar or higher minimum inhibitory concentration. Additionally, the extravascular kinetics of azithromycin are associated with bactericidal activity against pathogens such as Staphylococcus aureus, Streptococcus pneumoniae and Escherichia coli. Intracellular pathogens are susceptible to azithromycin and it is believed that the agent penetrates and remains within host cells infected by organisms including Mycobacterium avium, Legionella pneumophila and Borrelia burgdorferi. This paper reviews the in vivo efficacy of azithromycin and standard agents in animal models of infection, especially those involving intracellular pathogens.

Animals↗
PubMed1991

Gynaecological tissue levels of azithromycin.

In an open study the concentrations of azithromycin in plasma, urine, peritoneal fluid and gynaecological tissue in 20 patients undergoing elective gynaecological surgery were compared. Patients were allocated to one of four groups and all patients received a single 500 mg oral dose of azithromycin prior to surgery. In Group I, the dose was administered 24 h before surgery. In Groups II, III and IV it was administered 48, 72 and 96 h, respectively, prior to surgery. A total of 19 patients completed the study; one patient had peri-operative complications and did not proceed to surgery. High concentrations of azithromycin were found in gynaecological tissue up to 96 h after administration. The mean maximum observed concentration 24 h after administration was 1.44 +/- 0.22 micrograms/g. Using all data, the depletion rate constant was 0.0104 h-1, equivalent to a half-life of approximately 67 h. The mean concentration of drug in peritoneal fluid was approximately 9% of the mean concentration in gynaecological tissue. Tissue and peritoneal fluid azithromycin concentrations were much higher than plasma levels at the time of surgery. Detectable plasma levels were only found in four patients from Groups I and II. Six percent of the total dose was excreted in the urine during the seven-day period after drug administration. The single dose of azithromycin was well tolerated by all the patients in this study and no treatment-related side effects or laboratory test abnormalities were seen. It is concluded that a single 500 mg oral dose of azithromycin produces high and sustained levels in gynaecological tissue up to 96 h after administration.

Adolescent↗
PubMed1991

Double-blind, double-dummy comparison of azithromycin and cephalexin in the treatment of skin and skin structure infections.

In this double-blind, randomised trial conducted in 22 centres in the USA, azithromycin given over five days, as a once-a-day regimen, (500 mg on day 1, 250 mg on days 2-5) was compared with cephalexin (500 mg b.i.d.) given for ten days in the treatment of patients with skin and skin structure infections. A total of 366 patients entered the study and 179 of these were eligible for the efficacy analysis. The overall clinical response to azithromycin was 94.0%, compared with 95.8% for cephalexin. The clinical cure rates were 53.0% for azithromycin and 59.4% for cephalexin; the respective improvement rates were 41.0% and 36.5%. Distribution of response (cured, improved, failed) was similar in each group (p = 0.37). The bacteriological eradication rate for azithromycin-treated patients was 94.2% and for cephalexin-treated patients was 90.3% (p = 0.34). Clinical and bacteriological response was similar in each group for all primary diagnoses. The two antibiotics were well tolerated, the overall incidence of side effects being 13.7% with approximately 60% due to gastrointestinal disturbances. In all but one case (cephalexin) the severity of the reported side effects was mild or moderate. Six patients withdrew from the study due to treatment-related events; five had been treated with azithromycin and one with cephalexin. In summary, a five-day, once-daily regimen of azithromycin was as effective as a ten-day, twice-daily regimen of cephalexin in the treatment of patients with skin and skin structure infections.

Abscess↗
PubMed2005

Interaction of the macrolide antibiotic azithromycin with lipid bilayers: effect on membrane organization, fluidity, and permeability.

PURPOSE: To investigate the effect of a macrolide antibiotic, azithromycin, on the molecular organization of DPPC:DOPC, DPPE:DOPC, SM:DOPC, and SM:Chol:DOPC lipid vesicles as well as the effect of azithromycin on membrane fluidity and permeability. METHODS: The molecular organization of model membranes was characterized by atomic force microscopy (AFM), and the amount of azithromycin bound to lipid membranes was determined by equilibrium dialysis. The membrane fluidity and permeability were analyzed using fluorescence polarization studies and release of calcein-entrapped liposomes, respectively. RESULTS: In situ AFM images revealed that azithromycin leads to the erosion and disappearance of DPPC and DPPE gel domains, whereas no effect was noted on SM and SM:cholesterol domains. Although azithromycin did not alter the permeability of DPPC:DOPC, DPPE:DOPC, SM:DOPC, and SM:Chol:DOPC lipid vesicles, it increased the fluidity at the hydrophilic/hydrophobic interface in DPPC:DOPC and DPPE:DOPC models. This effect may be responsible for the ability of azithromycin to erode the DPPC and DPPE gel domains, as observed by AFM. CONCLUSIONS: This study shows the interest of both AFM and biophysical methods to characterize the drug-membrane interactions.

Anti-Bacterial Agents↗
PubMed1991

Clinical microbiology of azithromycin.

Azithromycin contains an aza-methyl substitution in the 15-membered aglycone ring and as such it is the prototype antibiotic of the azalide class, similar in mechanism of activity to the macrolides. It demonstrates a broad spectrum of activity against many aerobic and anaerobic Gram-positive species, and also inhibits a number of important aerobic and anaerobic Gram-negative bacteria. Significantly, azithromycin shows good activity against Haemophilus influenzae, an organism against which older macrolide antibiotics have proved disappointing. It is highly effective in inhibiting clinically significant intracellular pathogens such as Chlamydia trachomatis and Legionella. Bactericidal activity is seen for certain streptococci and for H. influenzae. Closely linked with azithromycin's microbiologic activity are its novel pharmacokinetics. Azithromycin moves rapidly from blood to tissue compartments where it remains for prolonged periods. Although serum concentrations remain low, the levels attained in the tissues (often greater than 2 mg/kg) are higher than the minimum inhibitory concentration for many common pathogens, and delivery of drug to infection sites by phagocytic cells contributes to these concentrations. This penetration into eukaryotic and prokaryotic cells may be responsible for azithromycin's expanded spectrum of activity, particularly against intracellular organisms. The use of antibiotic blood levels as breakpoints for susceptibility would appear to be inappropriate in the case of azalides. Rather, levels of drug at the tissue site of infection should be considered as guides to predicting efficacy. The in vitro activity of azithromycin, together with its unique tissue pharmacodynamics, define an agent that should demonstrate utility in infections of the respiratory tract, skin and skin structures, and certain sexually transmitted diseases.

Animals↗
PubMed1991

Azithromycin in the treatment of uncomplicated genital chlamydial infections.

Chlamydia trachomatis is among the most prevalent of sexually transmitted diseases and causes serious sequelae, especially in women. A major difficulty facing the clinician has been the effective treatment of patients with chlamydial infections, since existing drugs require 7 or more days of multidose therapy, and hence considerable commitment from the patient. Many patients, especially those who are minimally symptomatic or asymptomatic, are likely to be noncompliant when given such multiple day regimens and thus may fail therapy. Azithromycin is an azalide antibiotic that has a minimum inhibitory concentration against C. trachomatis of between 0.03 and 0.25 mg/L, as well as good in vitro activity against other sexually transmitted pathogens that are often present concurrently. Azithromycin also achieves high intracellular concentrations, which may be beneficial in eradicating Chlamydia, an obligate intracellular pathogen. More importantly, azithromycin has high tissue bioavailability and a tissue half-life of between 2 and 4 days. These pharmacokinetic properties imply that the dosing period for azithromycin can be greatly reduced while still achieving high antimicrobial activity at sites of infection. Clinical experience to date shows that a single 1 g oral dose of azithromycin is as effective as a standard 7-day twice daily regimen of doxycycline and more effective than 7 days of ciprofloxacin in eradicating uncomplicated chlamydial genital infections. As such, azithromycin is the first single-dose therapy for the treatment of urethritis and cervicitis due to C. trachomatis. Single-dose therapy for chlamydial infection, which could be administered under supervision in the clinic, would be a significant advance in the management and public health control of chlamydial infections.

Azithromycin↗
PubMed2004

Effects of a brief course of azithromycin on soluble cell adhesion molecules and markers of inflammation in survivors of an acute coronary syndrome: A double-blind, randomized, placebo-controlled study.

BACKGROUND: The anti-chlamydial antibiotic, azithromycin, may improve outcome in patients who survive an acute coronary syndrome. The mechanisms are, however, poorly understood. The aims of this study were to define any relationship between Chlamydia pneumoniae seropositivity and levels of specific markers of endothelial activation (soluble cell adhesion molecules) and more general markers of inflammation (C-reactive protein [CRP] and interleukin-6 [IL-6]) and to assess whether azithromycin had any effect on such markers. METHODS: Patients who survived an acute coronary syndrome were randomized to receive treatment with azithromycin (n = 72) or placebo (n = 69) for 5 days. Before therapy, C pneumoniae IgA and IgG titers were checked, with serum levels of soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1, soluble E-selectin (sE-selectin), soluble P-selectin, high-sensitivity CRP, and IL-6. They were rechecked 3 months later. RESULTS: There were no significant correlations between C pneumoniae titers and levels of CRP, IL-6, or soluble cell adhesion molecules. However, azithromycin treatment significantly reduced mean sICAM-1 levels (P =.006). This effect was more marked in patients with elevated titers of C pneumoniae IgA and IgG. Soluble E-selectin levels were also reduced in patients who were seropositive, but no effects were seen on other endothelial or inflammatory markers. CONCLUSIONS: After an acute coronary syndrome, a 5-day course of azithromycin reduces levels of sICAM-1, a marker of endothelial cell activation. Although these data suggest a potentially beneficial role for azithromycin, they should be interpreted with caution.

Aged↗
PubMedDate not supplied

Plasmodium yoelii: activity of azithromycin in combination with pyrimethamine or sulfadoxine against blood and sporozoite induced infections in Swiss mice.

The efficacy of pyrimethamine or sulfadoxine administered in combination with azithromycin was examined in a rodent malaria model. Outbred Swiss mice infected with blood stage parasites were treated from day 0 to day 3 and efficacy of different regimens was monitored in terms of the curative response and the delay time to reach 2% parasitaemia (2% DT). Administration of azithromycin alone at 60 mg/kg/day produced curative response while lower doses showed marginally delayed 2% DT. A marked potentiation in activities of pyrimethamine (100-fold) or sulfadoxine (10-fold) was observed when administered at non-curative doses of 0.1 mg/kg/day in combination with azithromycin (30 mg/kg/day) against blood stage parasites. A combination of 10 mg/kg/day azithromycin with 0.3 mg/kg/day sulfadoxine was also curative. Likewise in the causal prophylactic test, a combination regimen comprising 1/16th and 1/3rd the individual curative doses of pyrimethamine and azithromycin, respectively, prevented the development of patent infection after Plasmodium yoelii sporozoite challenge. Our results suggest that a combination of azithromycin with the second line treatment regimen of fansidar may enhance the therapeutic efficacy of the latter and also provide better prophylaxis against Plasmodium falciparum malaria.

Animals↗
PubMed2006

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.

Administration, Oral↗
PubMed2002

A prospective, randomized trial of pyrimethamine and azithromycin vs pyrimethamine and sulfadiazine for the treatment of ocular toxoplasmosis.

OBJECTIVE: To compare the effects of two treatment regimens, one of which included azithromycin, for the treatment of sight-threatening (near optic disk or fovea) ocular toxoplasmosis. DESIGN: Prospective, randomized open-labeled multicenter study, masked in part with regard to evaluation. METHODS: PARTICIPANTS TOTAL ENROLLMENT: 46 patients with sight-threatening ocular toxoplasmosis; pyrimethamine and azithromycin group: 24 patients; pyrimethamine and sulfadiazine group: 22 patients. INTERVENTION: Patients were randomized into two treatment regimens. Group 1 was treated with pyrimethamine and azithromycin complemented with folinic acid and the addition of prednisone from day 3. Group 2 was treated with pyrimethamine and sulfadiazine complemented with folinic acid and the addition of prednisone from day 3. Patients used study medications daily for 4 weeks. Ocular and laboratory examinations were performed at least weekly during the observation period. The study was masked in part with regard to evaluation. MAIN OUTCOME MEASURES: An assessment was made of the time to resolution of the intraocular inflammatory activity, the size of the retinochoroidal lesion, and visual acuity before and after the treatment as well as all adverse effects of treatments. RESULTS: Adverse effects were more frequent in the pyrimethamine/sulfadiazine group (P <.04), and three patients in this group had to discontinue treatment. The time to resolution of inflammatory activity, decrease in size of retinochoroidal lesions, and optimal visual acuity did not differ between the two treatment groups. The number of patients who developed recurrences during the first year after treatment was similar for both groups. CONCLUSIONS: The efficacy of the multidrug regimen with pyrimethamine and azithromycin was similar to the standard treatment with pyrimethamine and sulfadiazine. However, the frequency and severity of adverse effects was significantly lower with a regimen containing pyrimethamine and azithromycin. Multidrug therapy with the combination of pyrimethamine and azithromycin appears to be an acceptable alternative for treatment of sight-threatening ocular toxoplasmosis.

Adolescent↗
PubMed1997

Disposition of oral azithromycin in humans.

BACKGROUND: The oral bioavailability of azithromycin is approximately 37% in healthy subjects; little is known about the disposition of the remaining 63% of the dose. This study attempted to describe the fate of azithromycin before absorption. METHODS: Twelve subjects with ileostomies in place for > 1 month were studied in this open-label, randomized, three-center, two-period, two-treatment crossover study. Subjects randomly received single 500 mg intravenous infusion (over 1 hour) or two 250 mg oral capsules after a fast for > 12 hours. Blood and ileostomy samples were collected serially after each administration and analyzed for azithromycin and two metabolites (descladinose and 9a-N-desmethyl metabolites) by HPLC with electrochemical detection. RESULTS: Mean +/- SD peak concentration values after oral and intravenous administration were 0.21 +/- 0.08 and 3.40 +/- 1.12 microgram/ml. Mean values for area under the serum concentration versus time curve were 1.27 +/- 0.65 and 7.14 +/- 1.34 micrograms x hr/ml, respectively. The absolute bioavailability of 16.2% was approximately one-half the value observed previously in healthy subjects. Recovery in ileostomy fluid (percent of dose in 24 hours) or azithromycin, descladinose, and 9a-N-desmethyl metabolites were 13%, 0.5%, and 1% (total, 15%) after intravenous dosing and 47%, 13%, and 2% (total, 62%) after oral dosing. Total and ileal clearances were 776 +/- 126 and 158 +/- 63 ml/min after intravenous dosing. CONCLUSION: Because more descladinose metabolite was detected after oral dosing, acid degradation of azithromycin before absorption contributed to some loss in oral bioavailability. Further, ileal clearance (biliary plus intestinal excretion clearance) in this population represented 21% of total clearance. Taken together, these data suggest that the cause of low oral bioavailability of azithromycin is the result of incomplete absorption rather than acid degradation or extensive first-pass metabolism.

Administration, Oral↗
PubMed1996

Efficacy of short-term treatment of pertussis with clarithromycin and azithromycin.

The recommended treatment for pertussis is erythromycin, 40 to 50 mg/kg per day for 2 weeks. The newly developed macrolides, clarithromycin and azithromycin, have been demonstrated to be superior to erythromycin because of improved absorption and a longer half-life. As a result, we conducted two separate comparison studies to evaluate the efficacies of clarithromycin, 10 mg/kg per day, twice a day for 7 days, and azithromycin, 10 mg/kg per day, once a day for 5 days, compared with the standard erythromycin regimen. A total of 17 patients, including 10 infants 1 year of age or less, for whom pertussis had been confirmed by culture, were allocated to receive either clarithromycin or azithromycin treatment, and each patient was matched (age, sex, and immunization status) with historical control subjects who had been treated with erythromycin. Eradication rates examined at 1 week after treatment were as follows: 9 of 9 with clarithromycin versus 16 of 18 with erythromycin (psi M-H = 1.13), and 8 of 8 with azithromycin versus 13 of 16 with erythromycin (psi M-H = 1.23). No bacterial relapse after treatment was detected in either group. All isolated strains of Bordetella pertussis were susceptible to clarithromycin, azithromycin, and erythromycin, and no change in drug susceptibility has been confirmed for the past 20 years in Japan. Because of the very low incidence of pertussis resulting from widespread use of acellular pertussis vaccination, this study did not enroll a large number of patients; however we conclude that short-term treatment with clarithromycin or azithromycin is expected to be equal or superior to the standard long-term erythromycin regimen for pertussis.

Adolescent↗
PubMed2002

Long term azithromycin in children with cystic fibrosis: a randomised, placebo-controlled crossover trial.

BACKGROUND: The macrolide antibiotic azithromycin has anti-inflammatory properties potentially beneficial in cystic fibrosis. Since findings of open pilot studies seemed to show clinical benefit, we undertook a formal trial. METHODS: 41 children with cystic fibrosis, aged 8-18 years, and with a median forced expiratory volume in 1 s (FEV1) of 61% (range 33-80%) participated in a 15-month randomised double-blind, placebo-controlled crossover trial. They received either azithromycin (bodyweight < or =40 kg: 250 mg daily, >40 kg: 500 mg daily) or placebo for 6 months. After 2 months of washout, the treatments were crossed over. The primary outcome was median relative difference in FEV1 between azithromycin and placebo treatment periods. Sputum cultures, sputum interleukin 8 and neutrophil elastase, exercise testing, quality of life, antibiotic use, and pulmonary exacerbation rates were secondary outcome measures. Side-effects were assessed by pure tone audiometry and liver function tests. Analysis was by intention-to-treat. FINDINGS: Median relative difference in FEV1 between azithromycin and placebo was 5.4% (95% CI 0.8-10.5). 13 of 41 patients improved by more than 13% and five of 41 deteriorated by more than 13% (p=0.059). Forced vital capacity and mid-expiratory flow did not significantly change overall. 17 of 41 patients had 24 fewer oral antibiotic courses when on azithromycin than when taking placebo, and five had six extra courses (p=0.005). Sputum bacterial densities, inflammatory markers, exercise tolerance, and subjective well-being did not change. There were no noticeable side-effects. INTERPRETATION: A 4-6-month trial of azithromycin is justified in children with cystic fibrosis who do not respond to conventional treatment. The mechanism of action remains unknown.

Adolescent↗
PubMed2002

A double-blind placebo-controlled trial of azithromycin as an adjunct to non-surgical treatment of periodontitis in adults: clinical results.

BACKGROUND/AIMS: The aim of the study was to investigate the clinical and microbiological effects of azithromycin as an adjunct to the non-surgical treatment of periodontitis in adults. Azithromycin is an antibiotic which is taken up by phagocytes and is released over long periods in inflamed tissue but requires a total of only three doses of 500 mg to produce its therapeutic effect. METHOD: 46 patients were treated in a double-blind placebo-controlled study with assessments at weeks 0, 1, 2, 3, 6, 10 and 22. Throughout the trial measurements were made of plaque, gingival bleeding, calculus, probing pocket depths and bleeding on probing. Microbiological sampling was carried out from a selected pocket >or=6 mm at each visit. The regime employed consisted of OHI, scaling and root planing at weeks 0, 1 and 2 with reinforcement of OHI and minimal scaling at weeks 6, 10 and 22. Patients were randomly assigned to receive either azithromycin, (A), or placebo capsules, (C), 500 mg, 1x daily for 3 days at week 2. 44 patients completed the study. Mean pocket depths were analysed using analysis of covariance in 3 groups with initial pocket depth values of 1-3 mm, 4-5 mm and >or=6 mm. RESULTS: The results of the microbiology have been reported in a separate paper. The clinical data showed that by week 22 a lower % of pockets initially >5 mm deep remained above that level in the 23 patients taking azithromycin (A), than the 21 taking the placebo (C), (A, 5.6%; C, 23.3%). Also at week 22, for pockets initially 4 mm or more, the test group had fewer pockets >3 mm deep (A, 26.1%; C, 44.3%), fewer failing to improve in probing depth (A, 6.6%; C, 21.6%) and fewer continuing to bleed on probing (A, 46.9%; C, 55.6%) when compared with the control group. Pocket depths initially 4-5 mm or 6-9 mm analysed by analysis of covariance showed lower mean pocket depths in the patients on azithromycin, at weeks 6, 10 and 22, (pockets initially 4-5 mm, p<0.001 on all occasions, pockets initially 6-9 mm, p<0.001, week 6; p< 0.003, week 10; p<0.001, week 22). CONCLUSIONS: Azithromycin may be a useful adjunct in the treatment of adult periodontitis, particularly where deep pockets are present.

Adult↗
PubMed2002

The effects of steady-state erythromycin and azithromycin on the pharmacokinetics of sildenafil in healthy volunteers.

AIMS: Sildenafil, an effective oral treatment for erectile dysfunction, is predominantly metabolized by the cytochrome P450 isozyme 3A4, which is inhibited by a number of the macrolide antibiotics. Therefore, two placebo-controlled, parallel-group studies were conducted to evaluate the effects of multiple doses of erythromycin and azithromycin on the pharmacokinetics, safety and tolerability of a single oral 100-mg dose of sildenafil. METHODS: In the erythromycin interaction study, 26 male volunteers (18--45 years of age) received open-label sildenafil 100 mg on day 1. Half received blinded erythromycin (500 mg) twice daily on days 2--6, and the other half received placebo. On day 6, all subjects received a second 100-mg dose of sildenafil. In the azithromycin interaction study, 24 male volunteers (19--33 years of age) received open-label 100 mg sildenafil on day 1. Half then received blinded azithromycin (500 mg) once daily on days 2--4, and the other half received placebo. On day 4, all subjects received another 100-mg dose of sildenafil. In both studies, blood samples were collected on the first and last study day for the analysis of plasma concentrations of sildenafil and its primary metabolite, UK-103,320. RESULTS: Repeated dosing with erythromycin caused statistically significant increases in the AUC and Cmax of sildenafil (2.8-fold and 2.6-fold, respectively) but had no effect on Tmax, kel or t1/2. A statistically significant 1.4-fold increase in the AUC of UK-103,320 was also observed, as well as a significant decrease in kel, resulting in an increase of about 1 h in t1/2. In contrast, repeated dosing with azithromycin caused no significant change in any pharmacokinetic parameter of either sildenafil or UK-103,320. Erythromycin, azithromycin and sildenafil were well tolerated; adverse events were mild and transient. No subject withdrew from either trial for any reason related to study drug. CONCLUSIONS: These results indicate that erythromycin modifies the pharmacokinetics of sildenafil by inhibiting its CYP3A4-mediated first-pass metabolism. Given these data, a lower starting dose of sildenafil (25 mg) may be considered for patients receiving erythromycin or other potent CYP3A4 inhibitors. Azithromycin did not affect the pharmacokinetics of sildenafil; therefore, no adjustment in dosage is necessary for patients receiving these drugs concomitantly.

Adult↗