Using Polar Ion-Pairs to Control Drug Delivery to the Airways of the Lungs

Photocatalytic Degradation Mechanism of the Pharmaceutical Agent Salbutamol Using the Mn-Doped TiO2 Nanoparticles Under Visible Light Irradiation

In the present work, the photocatalytic degradation of salbutamol [2-(tert-butylamino)-1-(4-hydroxyl-3-hydroxymethylphenyl)ethanol] under visible irradiation using Mn-doped TiO₂ is investigated. The Mn-doped TiO₂ nanoparticles were synthesized by the sol-gel method with ratios of 0.1, 0.2, and 0.3%. Significant characteristics, including the rutile/anatase phases ratio, specific surface area, and band gap energy, were due to the amount of Mn doping; the narrowest band gap energy of 2.80 eV was observed in 0.2% Mn-doped TiO₂ with specific surface areas of 89.36 m²/g and 10.87/89.13 of rutile/anatase phases. The investigation involved salbutamol photocatalytic degradation, a kinetic study, and the identification of intermediate compounds. The results indicated that 0.2% Mn-doped TiO₂ obtained the best salbutamol removal of 95% under an irradiation time of 180 min. Salbutamol slowly degraded to the intermediate compounds in the first 60 min (k = 0.0088 1/min), and these intermediate compounds were dramatically mineralized to small hydrocarbon fragments and carbon dioxide in the later irradiation times (k = 0.0179 1/min). According to the high-performance liquid chromatography-mass spectrometry (HPLC-MS) results, possible degradation pathways of salbutamol were proposed: 2-(tert-butylamino)-1-(3,4-dihydroxyphenyl)ethanone, 2-(tert-butylamino)-ethanol, and 2-(tert-butylamino)-1-(4-hydroxyl-3-hydroxymethylphenyl)ethanone were initially formed and then transformed to 2-(methylamino)-1-(3,4-dihydroxyphenyl)ethanone, 2-(tert-butylamino)-acetic acid, hydroquinone, and 1-(4-hydroxylphenyl)ethanol, respectively. The mineralization of all intermediate compounds was verified by 90% chemical oxygen demand (COD) reduction, and the effluent contained a relatively low COD concentration of 7.8 mg/L.

Inhaled Medicines: Past, Present, and Future

The purpose of this review is to summarize essential pharmacological, pharmaceutical, and clinical aspects in the field of orally inhaled therapies that may help scientists seeking to develop new products. After general comments on the rationale for inhaled therapies for respiratory disease, the focus is on products approved approximately over the last half a century. The organization of these sections reflects the key pharmacological categories. Products for asthma and chronic obstructive pulmonary disease include β -2 receptor agonists, muscarinic acetylcholine receptor antagonists, glucocorticosteroids, and cromones as well as their combinations. The antiviral and antibacterial inhaled products to treat respiratory tract infections are then presented. Two "mucoactive" products-dornase α and mannitol, which are both approved for patients with cystic fibrosis-are reviewed. These are followed by sections on inhaled prostacyclins for pulmonary arterial hypertension and the challenging field of aerosol surfactant inhalation delivery, especially for prematurely born infants on ventilation support. The approved products for systemic delivery via the lungs for diseases of the central nervous system and insulin for diabetes are also discussed. New technologies for drug delivery by inhalation are analyzed, with the emphasis on those that would likely yield significant improvements over the technologies in current use or would expand the range of drugs and diseases treatable by this route of administration. SIGNIFICANCE STATEMENT: This review of the key aspects of approved orally inhaled drug products for a variety of respiratory diseases and for systemic administration should be helpful in making judicious decisions about the development of new or improved inhaled drugs. These aspects include the choices of the active ingredients, formulations, delivery systems suitable for the target patient populations, and, to some extent, meaningful safety and efficacy endpoints in clinical trials.

Control of the Lung Residence Time of Highly Permeable Molecules after Nebulization: Example of the Fluoroquinolones

Pulmonary drug delivery is a promising strategy to treat lung infectious disease as it allows for a high local drug concentration and low systemic side effects. This is particularly true for low-permeability drugs, such as tobramycin or colistin, that penetrate the lung at a low rate after systemic administration and greatly benefit from lung administration in terms of the local drug concentration. However, for relatively high-permeable drugs, such as fluoroquinolones (FQs), the rate of absorption is so high that the pulmonary administration has no therapeutic advantage compared to systemic or oral administration. Formulation strategies have thus been developed to decrease the absorption rate and increase FQs’ residence time in the lung after inhalation. In the present review, some of these strategies, which generally consist of either decreasing the lung epithelium permeability or decreasing the release rate of FQs into the epithelial lining fluid after lung deposition, are presented in regards to their clinical aspects.