Removal Of Azithromycin Research Articles

Adsorption-Membrane Hybrid Approach for the Removal of Azithromycin from Water: An Attempt to Minimize Drug Resistance Problem

In this study, activated carbon (AC) and magnetic activated carbon (MAC) were prepared from Dalbergia sissoo sawdust for the removal of antibiotic Azithromycin (AZM) from aqueous solution. The effect of initial concentration, contact time, pH, adsorbent dosage, and the temperature were investigated for both the adsorbents. The optimum AZM concentration, contact time, pH and adsorbents dosages were found to be 80 mg/L, 120 min, 6 and 7 (pH, respectively, for AC and MAC), and 0.1 g (for both AC and MAC), respectively. The isothermal data of both sets of experiments correlated well with the Langmuir isotherm model, while the kinetic data with the pseudo-second-order model. The adsorption of AZM on both adsorbents was found to be favorable, which is evident in the values of the thermodynamic parameters (ΔH = −26.506 and −24.149 KJ/mol, ΔS = 91.812 and 81.991 J/mol K, respectively, for AC and MAC). To evaluate the effect of AC and MAC on the membrane parameters, a continuous stirred reactor was connected with ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) membranes. High % retention and improved permeate flux (around 90%) were obtained for AC/UF, AC/NF AC/RO, MAC/UF, MAC/NF, and MAC/RO treatments. The percent retention of AZM observed for AC/UF, AC/NF AC/RO was higher than MAC/UF, MAC/NF, and for MAC/RO hybrid processes due to greater surface area of AC than MAC.

Performance Evaluation and Parameter Optimization of Moving Bed Biofilm Reactor (MBBR) along with Electrocoagulation for Removal of Azithromycin

Antibiotics from hospital discharge wastewater are known to be one of the most significant water contaminants. Environmental researchers suggest the attainment of effective and biological approaches for the elimination of these contaminants. This work aims to study the efficiency of an azithromycin (AZX) removal using moving bed biofilm reactor (MBBR) combined with electrocoagulation and parameters optimization using a response surface methodology for hospital wastewater (RSM), i.e., MLSS (A), pH (B), HRT (C) and Electrode distance (D). The present research was conducted using PVC gel on a pilot scale for removing a detergent from the wastewater of hospital reactors with continuous hydraulic flux. The impact on the device concentration of independent variables, including duration of touch, percentage of the media, and the concentrations of 1200-3200 mg/l of mixed liquor suspended solids (MLSS). Closed laboratory procedure for measuring AZX concentration, azithromycin (AZX), and chemical oxygen requirement (COD) 1500-2400 mg/l is used. The findings showed that AZX and COD with PVC gel retention times are 92.3 and 95.8 percent, respectively, of 24 hours, with an MLSS concentration of approximately 3,200 mg/l. It was shown that the MBBR device has great productivity in detergent deletion from hospital waste wastewater as a bio-friendly compatible process and can produce regular performance effluents at an appropriate period. The experiment was performed using an electrochemical process, electrolysis with independently variable electrical electrodes, i.e., voltage, duration of touch, and electrolyte concentration. The complete process was optimized for the said reaction using Design-Expert software. The response surface method was used to optimize the operational parameters and show that a contact period of 35 minutes, voltage 12 V, electrolyte concentration of 0.35 M with electrode distance 1.25 cms gives 89% removal efficiency. The model for the three variables recommended by the response surface is a quadratic response.

PECVD synthesis of ZnO/Si thin film as a novel adsorbent for removal of azithromycin from water samples

ABSTRACT In the current study, ZnO/Si thin film was prepared through a plasma-enhanced chemical vapour deposition (PECVD) method and used for the elimination of azithromycin (AZM) from various real samples. Some specs about the structure and morphology of the ZnO/Si thin film were systematically examined utilising approaches such as X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and Scanning electron microscopy (SEM). The adsorption of AZM on the ZnO/Si thin film was accomplished under various statuses that are equilibrium time = 45 min, adsorbent dose = 0.025, pH solution = 7.0, and primary AZM concentration = 15 mg L−1. Four models were utilised to monitoring the adsorption kinetic of AZM onto ZnO/Si thin film: pseudo-first order (PFO), pseudo-second order (PSO), Elovich (E) and intraparticle diffusion (ID) models. Equilibrium data were fitted to Langmuir (L), Freundlich (F), Temkin (T) and Redlich-Peterson (R-P) isotherm models. The elimination efficiency of AZM via ZnO/Si thin film was evaluated in three real samples. Finally, it should be noted that AZM loaded on the adsorbent could be easily desorbed with 0.1 mol L−1 HNO3 and the adsorbent showed good reusability for adsorption of the studied drug.

Potential application of persulfate and simulated sunlight radiation on azithromycin removal

Potential application of persulfate and simulated sunlight radiation on azithromycin removal

Use of low frequency ultrasound for water treatment: Data on azithromycin removal.

Azithromycin (AZT) is a broad-spectrum antibiotic present in different aqueous matrices due to its incomplete removal using conventional water treatments. Ultrasound (US) is an advanced oxidation technology that has demonstrated its capacity to degrade different types of organic molecules due to the generation of cavitation bubbles or cavities that promote the generation of radicals.In this paper, data regarding the use of low-frequency US (40 kHz) in the removal of AZT are presented. Tests were carried out at lab scale for 60 min considering a reaction volume of 300 mL (pollutant initial concentration 1.0 mg L−1). The effect of operational parameters such as pH, ultrasound power, the presence of external agents like ferrous ions, hydrogen peroxide, and UV radiation were evaluated. In general, obtained data show that under the experimental reaction conditions, it is feasible to reach extents of AZT removal ∼50.0%, and that the presence of other species in the medium could inhibit the reaction, mainly due to scavenging effects. This information is relevant to future applications of US, at pilot or real scale, in the treatment of water with presence of AZT or similar organic pollutants.

Effect-Based Identification of Hazardous Antibiotic Transformation Products after Water Chlorination.

Antibiotic transformation products (TPs) generated during water treatment can be considered as an environmental concern, since they can retain part of the bioactivity of the parent compound. Effect-directed analysis (EDA) was applied for the identification of bioactive intermediates of azithromycin (AZI) and ciprofloxacin (CFC) after water chlorination. Fractionation of samples allowed the identification of bioactive intermediates by measuring the antibiotic activity and acute toxicity, combined with an automated suspect screening approach for chemical analysis. While the removal of AZI was in line with the decrease of bioactivity in chlorinated samples, an increase of bioactivity after complete removal of CFC was observed (at >0.5 mgCl2/L). Principal component analysis (PCA) revealed that some of the CFC intermediates could contribute to the overall toxicity of the chlorinated samples. Fractionation of bioactive samples identified that the chlorinated TP296 (generated from the destruction of the CFC piperazine ring) maintained 41%, 44%, and 30% of the antibiotic activity of the parent compound in chlorinated samples at 2.0, 3.0, and 4.0 mgCl2/L, respectively. These results indicate the spectrum of antibacterial activity can be altered by controlling the chemical substituents and configuration of the CFC structure with chlorine. On the other hand, the potential presence of volatile DBPs and fractionation losses do not allow for tentative confirmation of the main intermediates contributing to the acute toxic effects measured in chlorinated samples. Our results encourage further development of new and advanced methodologies to study the bioactivity of isolated unknown TPs to understand their hazardous effects in treated effluents.

Challenges of municipal wastewater reclamation for irrigation by MBR and NF/RO: Physico-chemical and microbiological parameters, and emerging contaminants

Climate change and the increased demand for food amplified the global problem with water supply for irrigation. This work deals with the reclamation of municipal wastewater (MWW) for irrigation by a membrane bioreactor (MBR), nanofiltration (NF), and reverse osmosis (RO). The emphasis was on the comparison of physico-chemical and microbiological parameters with the World Health Organization (WHO) and the European Union (EU) guidelines. In addition, the detection and removal of contaminants of emerging concern (CEC) from the Watch List (EU Decision 2015/495) were examined. Firstly, the MWW was monitored (physico-chemical and microbiological parameters, trace elements, and occurrence of CECs) for six months. Thereafter, the MWW was treated with MBR, NF, and RO. The reclaimed water satisfied the physico-chemical and microbiological quality requirements only after additional NF/RO treatment. Membrane bioreactor efficiently removed methiocarb (>99.9%), tri-allate (>99.9%), clothianidin (88.0%), and clarithromycin (71.9–74.2%), while the removal of azithromycin, acetamiprid, and oxadiazon was around 30%. The low and even negative removal during MBR treatment was observed for diclofenac (15%), clothianidin (−14%), imidacloprid (−18%), and diclofenac (−157%). Additional treatment of MBR effluent with NF90 and XLE membranes resulted in complete rejection of detected CECs, while NF270 membrane achieved results between 75% and 91%.

Comparison of Azithromycin Removal from Water Using UV Radiation, Fe (VI) Oxidation Process and ZnO Nanoparticles.

Antibiotics are resistant to biodegradation, and their removal by biological processes is difficult. The purpose of this study was to investigate the removal of azithromycin from water using ultraviolet radiation (UV), Fe (VI) oxidation process and ZnO nanoparticles. The effect of different parameters such as pH, temperature, hydraulic retention time (HRT), the concentration of Fe (VI) and ZnO nanoparticles and UV intensity on the removal of azithromycin from water was investigated. The optimal conditions for the removal of azithromycin were a pH of 2, a temperature of 25 °C, a HRT of 15 min, and a ratio of ZnO nanoparticles to the initial concentration of azithromycin (A/P) of 0.00009 which was fitted by Langmuir isotherm. In addition, the optimal conditions for the removal of azithromycin using UV radiation were a pH of 7, a temperature of 65 °C, a HRT of 60 min, and UV radiation power of 163 mW/cm2. For the Fe (VI) oxidation process, the optimal conditions were a pH of 2, a temperature of 50 °C and a HRT of 20 min. Also, the optimal ratio of Fe (VI) to the initial concentration of antibiotic was between 0.011 and 0.012. The results of this study showed that the Fe (VI) oxidation process, UV radiation, and ZnO nanoparticles were efficient methods for the removal of azithromycin from water.

Easy to get, but not always easy to treat - Clinical and serological failure with Azithromycin in Syphilis: Time to adapt national guidelines?

Background Data since 2014 has shown a rise in the incidence of Syphilis especially amongst heterosexuals. In national guidelines, Macrolides remain an alternative treatment option although their efficacy has been long disputed. We describe a case of a patient with clinical and serological failure with Azithromycin treatment. Methods A 46 year old female presented with painful genital ulceration confirmed as primary syphilis. Sexual transmission infection testing was negative. She described an allergy (rash) to Amoxicillin and was given Doxycycline 100mg twice daily for 14 days. On day 5 she developed an urticarial rash and was changed to Azithromycin, 2g stat and 500mg daily for 10 days. Results There was initial serological response in her rapid plasma reagin (RPR) to 1:2 from 1:8 at 1 month, but at 5 months an RPR of 1:64 was seen with signs of secondary syphilis - a rash and a sore mouth. Re-infection was ruled out, she was re-treated with Azithromycin and her RPR reduced to 1:2, but she had a persistent macular rash. Following review by Infectious Diseases, 14 days of intravenous Ceftriaxone 1g daily was given. On day 10, her RPR rose to 1:64 but 3 months after fell to 1:4 and has been serofast since without further signs of Syphilis. Conclusion Patients treated with Macrolides should be closely monitored. Consideration should be given for desensitisation in patients with reported Penicillin allergy. As with pregnancy, consideration should be given to the removal of Azithromycin as an alternative treatment in national guidelines.

Use of photo-fenton for macrolide antibiotic azithromycin removal

Azithromycin (AZT) is one of the most used antibiotics worldwide. This has led to its introduction into different environmental compartments, which implies that conventional technologies used in wastewater treatment are not enough to remove this kind of pollutants. Photo-Fenton is an advanced oxidation process in which ferrous ions (Fe2+), under light radiation, catalyzes H2O2 decomposition generating hydroxyl free radicals (HO?) which have the potential to oxidize different organic molecules. In this way, this study presents the main results regarding the evaluation of photo-Fenton using simulated sunlight in the removal of AZT from aqueous solutions. The effects of operational parameters such as ferrous ions and hydrogen peroxide initial concentrations were assessed. In addition, some tests were carried out in order to evaluate the extent of pollutant mineralization considering the dissolved organic carbon and the nitrate ions presence on treated samples. In general, results indicated that Fe2+ and H2O2 initial concentrations have a significant effect on pollutant removal.

Use of simulated sunlight radiation and hydrogen peroxide in azithromycin removal from aqueous solutions: Optimization & mineralization analysis

Abstract Azithromycin (AZT) is a broad-spectrum antibiotic from the group of macrolides that acts against several Gram-positive and Gram-negative bacteria, which has promoted its use in the treatment of different respiratory and sexually transmitted diseases. However, its presence in environmental matrices and in the effluents of conventional wastewater treatment plants has been evidenced in recent years, which reflects the need to develop new treatment alternatives that allow its total removal and minimize the eventual adverse effects, selection of resistant bacterial strains, associated with its presence in water bodies. Simulated sunlight radiation and H2O2 were used to remove AZT from water assessing the effects of operational parameters like the solution initial pH and the peroxide concentration. Results indicate that hydroxyl free radical is the main responsible for pollutant removal but acidic solution conditions and larger H2O2 doses negatively affect OH• generation under the evaluated experimental conditions. Pollutant removal was almost complete after 120 min of photo-treatment. In addition, reduction of the organic carbon content in the treated samples was ∼50.0%; and a significant increase of nitrates concentration in solution was evidenced.

Removal of azithromycin from wastewater using advanced oxidation processes (UV/H2O2) and moving-bed biofilm reactor (MBBR) by the response surface methodology (RSM)

Antibiotics are among the major concerns in terms of environmental control due to their cumulative properties, adverse health effects on humans, and development of drug resistance. The present study aimed to investigate the efficiency of the combination of UV/H2O2 and moving-bed biofilm reactor (MBBR) systems in the removal of azithromycin from aqueous solutions using the response surface methodology (RSM). In the UV/H2O2 process, a low-pressure mercury vapor lamp with the power of eight Watts, wavelength of 254 nanometers, and intensity of 1.02 mw/cm2 was used to determine the effects of pH, azithromycin concentration, hydrogen peroxide concentration, and contact time on the removal efficiency of azithromycin. According to the obtained results, the highest removal efficiency in the UV/H2O2 process was obtained with the azithromycin concentration of 2 mg/L. Therefore, 2 mg/L of azithromycin was selected as the optimal concentration with the highest removal efficiency. Following that, the optimal concentration of azithromycin was injected into the MBBR reactor. In the combined process of UV/H2O2 and MBBR, the highest removal efficiency of azithromycin was 91.2%. Therefore, it could be concluded that the combined system of UV/H2O2 and MBBR had the highest efficiency in the removal of azithromycin from aqueous solutions.

Slovak natural zeolites as a suitable medium for antibiotics elimination from wastewater

Abstract Pharmaceuticals are one of the most used compounds present in various environmental compartments. Due to their high consumption and possible unhealthy effect on ecosystems, pharmaceuticals have been identified as “emerging organic contaminants”. Since these compounds have medium to high polarity, they end up in the water compartment after being used. This work deals with the sorption of three pharmaceutical substances from the therapeutic group of antibiotics. Specifically we have focused on Azithromycin, Clarithromycin and Erythromycin. Three fractions of the natural Slovak zeolites (200 μm, 0.5—1 mm and 1.5—2 mm) were used as the sorption medium. Experimental results have proven very effective sorption of antibiotics by zeolites. Azithromycin removal of over 99 % for all three zeolite fractions from wastewater treatment plant Stupava and wastewater treatment plant Devínska Nová Ves was achieved. Clarithromycin removal of 79 % for fraction 1—2.5 mm, 87.3 % for fraction 0.5—1 mm and of 99.8 % for fraction 200 μm from the effluent of wastewater treatment plant Stupava was observed. Erythromycin removal of 31.3 % for fraction 1—2.5 mm, 66.9 % for fraction 0.5—1mm and of 94.7 % for fraction 200 μm from effluent of wastewater treatment plant Stupava was measured. More than 95 % of Clarithromycin and Erythromycin were eliminated from the effluent of wastewater treatment plant Devínska Nová Ves. The highest elimination percentage was observed for the smallest zeolite fraction due to the highest specific surface area.

Adsorptive removal of azithromycin from aqueous solutions using raw and saponin-modified nano diatomite.

This study aims to investigate the performance and mechanism of raw (R-ND) and saponin-modified nano diatomite (M-ND) in the removal of azithromycin from aqueous solutions. Adsorbent characterization was performed using X-ray fluorescence, Brunauer-Emmett-Teller (BET), scanning electron spectroscopy, dynamic light scattering and energy-dispersive X-ray analyses. It was shown that the specific surface area of R-ND was 119.5 m2/g, 14-fold higher than that for raw diatomite, and for M-ND it was 90.1 m2/g. Various adsorption conditions, i.e. adsorbent dosage, pH, initial concentration and contact time were investigated. According to the results, despite reducing the specific surface area by 25%, modification of nano diatomite by saponin markedly enhanced its performance in the removal of azithromycin. The maximum adsorption capacity of R-ND and M-ND in the removal of azithromycin was 68 and 91.7 mg/g, respectively. Fourier transform infrared spectroscopy results revealed that azithromycin was adsorbed by O-H groups on the diatomite surface. Weber-Morris intra-particle diffusion (IPD) model suggested that while IPD is not the rate-controlling step in high concentrations of azithromycin, it is the only step that controls the rate of adsorption in low concentrations. In comparison to R-ND, M-ND showed a higher efficiency in the removal of azithromycin and, therefore, it can be used as a promising low-cost adsorbent to remove azithromycin from aqueous solutions.

Photocatalytic Degradation of Azithromycin by Nanostructured TiO₂ Film: Kinetics, Degradation Products, and Toxicity.

In this paper, nanostructured TiO2 film was prepared by the by sol-gel process and dip-coating technique with titanium tetraisopropoxide as a precursor. After heat treatment at 550 °C, the deposited film was characterized by means of micro-Raman spectroscopy and atomic force microscopy (AFM). It was found that the TiO2 film consisted of only the TiO2 anatase phase and showed a granular microstructure. Photocatalytic degradation of azithromycin by using sol-gel nanostructured TiO2 film was studied to define the most effective degradation process for potential use in wastewater treatment. Different factors were evaluated during photocatalysis, such as pH (3, 7, and 10), water matrix (ultrapure water and synthetic municipal waste water effluent), influence of another pharmaceutically active compound (sulfamethoxazole, one of the most often detected pharmaceutic compounds in waste waters), and radiation sources (low pressure ultraviolet (UV) mercury lamps with a UV-A and UV-C range; a light-emitting diode (LED) lamp with a radiation peak at 365 nm). The most effective degradation process was achieved with the UV-C irradiation source in matrices at pH 10. The water matrix had little effect on the photocatalytic degradation rates of azithromycin. The presence of sulfamethoxazole in the water matrix decreased the degradation rate of azithromycin, however, only in matrices with a pH level adjusted to 10. During the experiments, five azithromycin degradation products were identified and none of them showed toxic properties, suggesting effective removal of azithromycin. LED 365 nm as the irradiation source was not as effective as the UV-C lamp. Nevertheless, considering the cost, energy efficiency, and environmental aspects of the irradiation source, the LED lamp could be a “real-life” alternative.

UV activation of hydrogen peroxide for removal of azithromycin antibiotic from aqueous solution: determination of optimum conditions by response surface methodology

Antibiotics have caused major concerns in environmental control due to the cumulative adverse effects on human health. This study investigates the effect of four variables: pH (3, 6, and 9), azithromycin concentration (2, 6, and 10 mg/L), hydrogen peroxide concentration (2, 6, and 10 mg/L) and contact time (30, 45, and 60 min) on azithromycin removal efficiency. The initial concentration of azithromycin is the most important and effective parameter which is inversely related to the efficiency of the treatment process. Increasing the hydrogen peroxide concentration had the least effect on the efficiency of UV/H2O2. The highest removal efficiency (76%) was at azithromycin concentration of 2 mg/L, and hydrogen peroxide concentration of 10 mg/L, 60-min contact time, and pH 3 were obtained. The lowest efficiency (38%) was obtained at pH 9, contact time of 30 min, hydrogen peroxide concentration of 2 mg/L, and azithromycin concentration of 10 mg/L. According to the results, the 2-factorial interaction fitted model was governed by the purification process. The results of this study indicate the high efficiency of UV/H2O2 process in azithromycin removal from aqueous solutions.

Removal of Azithromycin from Aqueous Solution Using UV- Light Alone and UV Plus Persulfate (UV/Na2S2O8) Processes.

Azithromycin is among the broad-spectrum antibiotics that is widely available in various environmental systems and could have destructive effects on the ecosystem and human health due to its bacterial resistance. In this study, removal of azithromycin from wastewater using an advanced oxidation process of ultraviolet light with and without persulfate was investigated and effective parameters for the management of each of the processes were evaluated. The effect of different parameters including the concentration of Azithromycin antibiotic at levels 5, 15, 45 mgL-1; the concentration of persulfate at levels 1, 2, 4 mmol; pH at levels 5, 7, 9, contact time in 30, 60, 90 minute range of azithromycin removal was investigated. Ultraviolet light at a wavelength of 254 nanometers was used to irradiate the reactor. The results showed that azithromycin removal was significantly lower in the presence of ultraviolet radiation alone 58% with the removal efficiency than the case that ultraviolet radiation was used with sodium persulfate 98%. The best azithromycin removal conditions were obtained at the removal efficiency with the initial concentration of antibiotic 5 mgL-1, the concentration of persulfate 1mmol, and the contact time 30 min. and pH = 7. The rate of decrease in the concentration of residual azithromycin is increasing with increasing sodium persulfate concentration and decreasing the initial azithromycin concentration. This research can help to apply the integrated use of advanced oxidation processes to idealize decomposition-resistant compounds removal processes and to better understand the parameters affecting the removal.

An in vitro model of azithromycin-induced persistent Chlamydia trachomatis infection.

Single-dose azithromycin is recommended for treating Chlamydia trachomatis infections. Here, we established an in vitro cell model of azithromycin-induced persistent infection. Azithromycin inhibited the replication of C. trachomatis in a dose-time-dependent manner. Electron microscopy indicated that small inclusions in the induced model contained enlarged, aberrant and non-infectious reticulate bodies. RT-PCR showed that C. trachomatis still has the ability to express the unprocessed 16S rRNA gene in the model and that C. trachomatis recovered after the removal of azithromycin with a peak recovery time of 24 h. The mutations in 23S rRNA, L4 and L22 genes were not found in persistent infection, and qRT-PCR analysis showed that the relative expression level of euo in azithromycin treated infection was upregulated while omcB was downregulated. In summary, this study provides a novel in vitro cell model to examine the characteristics of azithromycin-induced persistent infection and contribute to the development of treatments for C. trachomatis infection.

COD REMOVAL FROM SYNTHETIC WASTEWATER CONTAINING AZITHROMYCIN USING COMBINED COAGULATION AND A FENTON-LIKE PROCESS

In this study, the COD removal of Azithromycin from synthetic wastewater (produced to have a composition similar to industrial wastewater) using a Fenton-like (Fe ˚ /H2O2) system in combination with coagulation has been investigated. Chemical oxygen demand (COD) was selected as the main parameter to assess treatment efficacy in the current study (COD˚ = 390mg/Lequivalent to 200mg/LAzithromycin). First, the coagulation process was carried out on the synthetic wastewater and the optimum conditions were determined and calculated. According to the results of this experiment, Poly Aluminum Chloride (PAX-18) was selected as the most appropriate coagulant. The results of the coagulation process indicated that COD removal efficacy under the optimum conditions of PAX-18 100mg/Land pH 7.0 was 82.14%. Then, a Fenton-like oxidation process was performed on the effluent of the coagulation process. The optimum conditions were determined and calculated for the Fenton-like process: [Fe ˚ ] = 0.36 mM/l, [H2O2]= 0.38 mM/l, and [pH]=7.0. Finally, in combined treatment (coagulation and the Fenton-like process together), the COD removal rose to 96.89% under optimum conditions. The findings of this study demonstrate that the combined processes of coagulation and Fenton-like oxidation under optimum conditions can play an important role in the COD removal of Azithromycin from industrial wastewater.

Azithromycin has an antiproliferative and autophagic effect on airway smooth muscle cells

Azithromycin is used in long-term, low-dose treatment of airway diseases where airway wall remodelling is present. Since it improves total score symptom and respiratory function of such patients, we hypothesise that azithromycin's additional clinical benefits are due to an inhibition of airway smooth muscle cell (SMC) proliferation. Rabbit tracheal SMCs were treated with azithromycin (10(-5) to 10(-6) M) in the presence or absence of 10% fetal bovine serum (FBS). The proliferation was estimated using the Cell Titer 96(R) AQ(ueous) One Solution Assay (Promega, Madison, WI, USA). Cell viability was assessed with Trypan blue staining and flow cytometry after 7-aminoactinomycin D (7-AAD) staining. Induction of autophagy was studied by indirect immmunofluorescence and/or Western blotting with antibodies against human smooth muscle alpha-actin, beclin 1, light chain 3 and caspase 3. The involvement of the phosphoinositide 3-kinase pathway was investigated with the inhibitors LY294002 and wortmannin. Incubation with azithromycin for 72 h in the presence of FBS reduced SMC proliferation and viability in a dose-dependent manner. Azithromycin treatment was accompanied by the formation of cytoplasmic vacuoles, characteristic of autophagy. All these effects were reversible after azithromycin removal and prevented by the autophagy inhibitor, 3-methyladenine, or LY294002, but not by wortmannin. In conclusion, azithromycin reduces proliferation and causes autophagy of airway SMCs.