Carrageenans can regulate the pulmonary absorption of antiasthmatic drugs and their retention in the rat lung tissues without any membrane damage

Polysaccharide-based formulations as potential carriers for pulmonary delivery - A review of their properties and fates

Polysaccharides can be elite carriers for therapeutic molecules due to their versatility and low probability to trigger toxicity and immunogenic responses. Local and systemic therapies can be achieved through particle pulmonary delivery, a promising non-invasive alternative. Successful pulmonary delivery requires particles with appropriate flowability to reach alveoli and avoid premature clearance mechanisms. Polysaccharides can form micro-, nano-in-micro-, and large porous particles, aerogels, and hydrogels. Herein, the characteristics of polysaccharides used in drug formulations for pulmonary delivery are reviewed, providing insights into structure-function relationships. Charged polysaccharides can confer mucoadhesion, whereas the ability for specific sugar recognition may confer targeting capacity for alveolar macrophages. The method of particle preparation must be chosen considering the properties of the components and the delivery device to be utilized. The fate of polysaccharide-based carriers is dependent on enzyme-triggered hydrolytic and/or oxidative mechanisms, allowing their complete degradation and elimination through urine or reutilization of released monosaccharides.

Hydrogels for controlled pulmonary delivery

A significant number of research articles have focused on pulmonary delivery as an alternative administration route owing to no first-pass metabolism, low protease activity, thin epithelium barrier and large surface area in the lung system. Controlled release in the pulmonary delivery system further reduces loading dose, frequency of dosing and systemic side effects, and also increases duration of action and patient compliance. Compared with other microparticles used in controlled-release pulmonary administration, hydrogels (3D polymeric matrix networks) have recently been investigated due to their swelling and mucoadhesive properties that could help bypass pulmonary delivery barriers. This review introduces controlled-release drug delivery to the lung, followed by a summary of currently available approaches for controlled-release pulmonary drug delivery. Lastly, the origin, advantages, detailed applications and concerns of hydrogels in pulmonary delivery are discussed.

Targeted drug delivery of Rifampicin to the lungs: formulation, characterization, and stability studies of preformed aerosolized liposome and in situ formed aerosolized liposome

PURPOSE

This study aimed at the preparation and characterization of preformed and in situ formed liposomes for sustained delivery to the lungs.

METHODS

Two different liposome formulations were prepared and subjected to characterization of physical parameters and drug release profile (% cumulative drug release and % drug retained). Formulations were then subjected to accelerated stability studies as per ICH guidelines.

RESULTS

In situ formed liposome showed better sustained release profile than the preformed liposome as it released sufficient amount of drug while retaining considerable amount of drug. Upon subjection to accelerated conditions for 60 days, preformed liposome lost the objective of being controlled release formulation.

Control of Pulmonary Absorption of Drugs by Various Pharmaceutical Excipients

In general, drugs are well absorbed from the lung, and the pulmonary absorption of therapeutic protein and peptide drugs, which are poorly absorbed from the gastrointestinal tract, was observed. However, locally acting drugs including antiasthmatic agents, bronchodilators, and expectorants should be localized for a long period in the lung tissues. In this study, the effects of various viscous vehicles on the absorption of theophylline and fluticasone propionate after intrapulmonary administration were examined in rats. Carrageenans were effective in regulating the absorption rate of these drugs. On the other hand, the bioavailability of therapeutic protein and peptide drugs with relatively high molecular weights from the pulmonary route is still poor when compared with the parenteral route. Therefore we examined the effects of chitosan and chitosan oligomers on the pulmonary absorption of interferon-alpha and salmon calcitonin in rats. Chitosan oligomers were effective in improving the pulmonary absorption of these drugs, and chitosan hexamer appeared to be markedly more effective than other oligomers. Furthermore, the present study indicated that chitosan oligomers did not cause any membrane damage to rat pulmonary tissues. In conclusion, it is suggested that various pharmaceutical excipients achieved the sustained pulmonary absorption of locally acting drugs and the improved pulmonary bioavailability for therapeutic protein and peptide drugs.