Clarithromycin targeting to lung: characterization, size distribution and in vivo evaluation of the human serum albumin microspheres

Azithromycin ameliorates sulfur dioxide-induced airway epithelial damage and inflammatory responses

Background

The airway epithelium (AE) forms the first line of defence against harmful particles and pathogens. Barrier failure of the airway epithelium contributes to exacerbations of a range of lung diseases that are commonly treated with Azithromycin (AZM). In addition to its anti-bacterial function, AZM has immunomodulatory effects which are proposed to contribute to its clinical effectiveness. In vitro studies have shown the AE barrier-enhancing effects of AZM. The aim of this study was to analyze whether AE damage caused by inhalation of sulfur dioxide (SO₂) in a murine model could be reduced by pre-treatment with AZM.

Methods

The leakiness of the AE barrier was evaluated after SO₂ exposure by measuring levels of human serum albumin (HSA) in bronchoalveolar lavage fluid (BALF). Protein composition in BALF was also assessed and lung tissues were evaluated across treatments using histology and gene expression analysis.

Results

AZM pre-treatment (2 mg/kg p.o. 5 times/week for 2 weeks) resulted in reduced glutathione-S-transferases in BALF of SO₂ injured mice compared to control (without AZM treatment). AZM treated mice had increased intracellular vacuolization including lamellar bodies and a reduction in epithelial shedding after injury in addition to a dampened SO₂-induced inflammatory response.

Conclusions

Using a mouse model of AE barrier dysfunction we provide evidence for the protective effects of AZM in vivo, possibly through stabilizing the intracellular microenvironment and reducing inflammatory responses. Our data provide insight into the mechanisms contributing to the efficacy of AZM in the treatment of airway diseases.

Design of Experiments (DoE) Approach to Optimize the Sustained Release Microparticles of Gefitinib

Background:

Gefitinib (GEF), the kinase inhibitor, is presently available as tablets to be taken orally in high doses of 250-500 mg per day due to its poor solubility. The solubility issues affect not only its onset of action but also the bioavailability. These drawbacks foresight the need to have an alternate dosage form, preferably a sustained release formulation.

Methods:

In the present study, microparticles were prepared by emulsion solvent evaporation using PLGA 50:50 (GEF-PLGA MP). A 32 factorial design was used to optimize the critical quality parameters to the set mean particle size in the range of 7.4±2.5 µm and entrapment efficiency of 80%. SEM microscopy of the prepared microparticles confirmed to have a spherical smooth shape. The GEFPLGA- MPs sustained the release of GEF for 72 hours. The first-order kinetics ruled the mechanism of drug release and was predicted to follow Fickian diffusion.

Result:

Anticancer efficacy was judged by the cytotoxicity studies using the L132 lung cancer cells. MTT assay showed 3-fold enhanced cytotoxicity of GEF loaded microparticles against L132 cells as compared to plain GEF.

Conclusion:

It was concluded that gefitinib can be efficiently loaded into the biodegradable polymer PLGA to provide sustained release of the drug.

High azithromycin concentration in lungs by way of bovine serum albumin microspheres as targeted drug delivery: lung targeting efficiency in albino mice

Background

Following administration, the antibiotic travels freely through the body and also accumulates in other parts apart from the infection site. High dosage and repeated ingestion of antibiotics in the treatment of pneumonia leads to undesirable effects and inappropriate disposition of the drug. By way of targeted lung delivery, this study was intended to eliminate inappropriate azithromycin disposition and to achieve higher azithromycin concentration to treat deeper airway infections.

Methods

The Azithromycin Albumin Microspheres (AAM) was prepared by emulsion polymerization technique. The optimized AAM was subjected to in vitro release study, release kinetics, XRD and stability studies. Further, in vivo pharmacokinetics and tissue distribution of azithromycin released from AAM and azithromycin solution in albino mice was investigated to prove suitability of moving forward the next steps in the clinic.

Results

The mean particle size of the optimized AAM was 10.02 μm, an optimal size to get deposited in the lungs by mechanical entrapment. The maximum encapsulation efficiency of 82.3 % was observed in this study. The release kinetic was significant and best fitted for Korsmeyer-Peppas model (R² = 0.9962, n = 0.41). The XRD and stability study showed favorable results. Azithromycin concentration in mice lungs (40.62 μg g⁻¹, 30 min) of AAM was appreciably higher than other tissues and plasma. In comparison with control, azithromycin concentration in lungs was 30.15 μg g⁻¹ after 30 min. The azithromycin AUC (929.94 μg h mL⁻¹) and intake rate (r_e) (8.88) for lung were higher and statistically significant in AAM group. Compared with spleen and liver, the targeting efficacy (t_e) in mice lung increased by a factor of 40.15 and ~14.10 respectively. Subsequently by a factor of 8.94, the ratio of peak concentration (C_e) in lung was higher in AAM treated mice. The AAM lung tissue histopathology did not show any degenerative changes.

Conclusions

High azithromycin concentration in albino mice lung was adequately achieved by targeted drug delivery.

Implications of designing clarithromycin loaded solid lipid nanoparticles on their pharmacokinetics, antibacterial activity and safety

The major obstacles for treatment of intracellular infections with clarithromycin are poor gastrointestinal solubility, short half-life (3–4 h), low oral bioavailability and hepatotoxicity.

Micro- and nanocarrier-mediated lung targeting

IMPORTANCE OF THE FIELD

Drug delivery to lungs appears to be an attractive proposition on account of the large surface area of the alveolar region; it provides tremendous opportunities to improve drug therapies both systemically and locally using new drug delivery systems. Administration of drugs directly to the lungs is the most appropriate route in the treatment of asthma and other pulmonary diseases such as tuberculosis, chronic obstructive pulmonary disease and lung cancer.

AREAS COVERED IN THIS REVIEW

This review focuses on the utilization of nano- and microcarriers such as microspheres, nanoparticles, liposomes, niosomes and dendrimers for targeted delivery of bioactive molecules to lungs.

WHAT THE READER WILL GAIN

This review sheds light on the current status of nano- and microcarrier-mediated lung targeting of bioactive compounds.

TAKE HOME MESSAGE

The literature review shows that carriers could supplement sustained drug delivery to the lungs, extended duration of action, reduced therapeutic dose, improved patient compliance, and reduced adverse effects of highly toxic drugs. There is still a need to identify more specific receptors that are present exclusively in the lungs. The identification of such receptors may also facilitate drug targeting to further specific parts of the lungs, such as bronchioles and alveoli.

Pharmacokinetics and lung-targeting characterization of a newly formulated enrofloxacin preparation

A new lung-targeting and controlled releasing preparation, enrofloxacin microsphere, was formulated and its physical properties, stability, pharmacokinetics and lung-targeting characteristics were tested in this study. The enrofloxacin microsphere prepared was demonstrated round and regular, which was easy to be dispersed and stable in both light stability test and heat stability test. Following intravenous administration of a single dose in dog, the drug concentration-time data in the lung were fitted most suitably with three-compartment open model. Compared with enrofloxacin injection (Baytril, half-life of distribution phase in the lung was shortened from 0.72 to 0.16 h, half-life of elimination phase in the lung was prolonged from 5.15 to 33.86 h and clearance of drug concentration in the lung was decreased from 0.603 to 0.267 L/h/kg. Lung-targeting parameters, including the relative intake rate (Re), targeting efficacy (Te) and the ratio of peak concentration (Ce), were calculated according to the pharmacokinetic parameters. The results showed that Re (2.48) and Ce (4.27) of the lung was much greater than that of other tissues and the ratio of Te(microsphere) to Te(Baytril) increased by a factor of 1.77 (compared with liver) to 3.51 (compared with spleen). Therefore, the enrofloxacin microsphere prepared in this study had controlled releasing and lung-targeting effects in dog.

Lung-targeting delivery of dexamethasone acetate loaded solid lipid nanoparticles

The objective of the present study was to develop a novel solid lipid nanoparticle (SLN) for the lung-targeting delivery of dexamethasone acetate (DXM) by intravenous administration. DXM loaded SLN colloidal suspensions were prepared by the high pressure homogenization method. The mean particle size, drug loading capacity and drug entrapment efficiency (EE%) of SLNs were investigated. In vitro drug release was also determined. The biodistribution and lung-targeting efficiency of DXM-SLNs and DXM-solutions (DXM-sol) in mice after intravenous administration were studied using reversed-phase high-performance liquid chromatography (HPLC). The results (expressed as mean +/- SD) showed that the DXM-SLNs had an average diameter of 552 +/- 6.5 nm with a drug loading capacity of 8.79 +/- 0.04% and an entrapment efficiency of 92.1 +/- 0.41%. The in vitro drug release profile showed that the initial burst release of DXM from DXM-SLNs was about 68% during the first 2 h, and then the remaining drug was released gradually over the following 48 hours. The biodistribution of DXM-SLNs in mice was significantly different from that of DXM-sol. The concentration of DXM in the lung reached a maximum level at 0.5 h post DXM-SLNs injection. A 17.8-fold larger area under the curve of DXM-SLNs was achieved compared to that of DXM-sol. These results indicate that SLN may be promising lung-targeting drug carrier for lipophilic drugs such as DXM.