Ibuprofen was microencapsulated with Eudragit RS using an o/w emulsion solvent evaporation technique. The effects of three formulation variables including the drug:polymer ratio, emulsifier (polyvinyl alcohol) concentration and organic solvent (chloroform) volume on the entrapment efficiency and microspheres size distribution were examined. The drug release rate from prepared microspheres and the release kinetics were also studied. The results demonstrated that microspheres with good range of particle size can be prepared, depending on the formulation components. The drug:polymer ratio had a considerable effect on the entrapment efficiency. However, particle size distribution of microspheres was more dependent on the volume of chloroform and polyvinyl alcohol concentration rather than the drug:polymer ratio. The drug release pattern showed a burst effect for all prepared microspheres due to the presence of uncovered drug crystals on the surface. It was shown that the release profiles of all formulations showed good correlation with the Higuchi model of release.

Pulmonary drug delivery of ciprofloxacin hydrochloride offers effective local antibacterial activity and convenience of easy application. Spray drying is a trustworthy technique for the production of ciprofloxacin hydrochloride microparticles. Quality by design (QbD), an up-to-date regulatory-based quality management method, was used to predict the final quality of the product. According to the QbD-based theoretical preliminary parameter ranking and priority classification, dry powder inhalation formulation tests were successfully performed in practice. When focusing on the critical parameters, the practical development was more effective and was in correlation with our previous findings. Spray drying produced spherical microparticles. The dry powder formulations prepared were examined by particle size analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction, differential scanning calorimetry, and in vitro drug release and aerodynamic particle size analyses were also performed. These formulations showed an appropriate particle size ranging between 2 and 4 μm and displayed an enhanced aerosol performance with fine particle fraction up to 80%.

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Respiratory infections cause an extensive health problem in the world. The common treatment for respiratory infections is the administration of antibiotics orally or parenterally in a high dose. Unfortunately, these therapies of high-dose antimicrobials have many disadvantages, such as severe side effects. Consequently, the development of an inhaled formulation provides the delivery of the therapeutic dose of the drug to the organ of interest without overt systemic effects. Novel technological advances have led to the development of inhaled antibiotics. Recent particle engineering techniques for dry powder inhalers (DPI) or mesh nebulizers have higher aerosolization efficiencies and promote the delivery of high-dose antibiotics to the lungs. However, advanced formulation strategies are in high demand for the development of new formulations for more types of antibiotics. Despite all the current research, patient compliance with pulmonary dosage forms remains to be very low because of the inappropriate administration techniques. Hence, this review focuses on three key aspects of the pulmonary dosage forms of antibiotics; the marketed products, the formulation approaches under research and innovative formulation strategies for achieving drug delivery through the respiratory tract.