Respiratory system surfactant

All the chemicals listed in Table 11.6, with the exception of surfactants, are volatile and attack the respiratory system upon inhalation. All readily defeat and attack the skin. It is not implied here that these products are... 

For the treatment of lung surfactant deficiency in premature human infants suffering from respiratory distress syndrome, limited clinical trials were performed showing that liposomes in the lung-instilled intratracheally either as an aerosolized mist (Ivey et al., 1977) or as a suspension via an endotracheal tube (Fujiwara et al., 1980)—rapidly improved lung function. No adverse effects were observed as a result of the supplementation with surfactant-like material. It appears, therefore, that liposomes are a suitable system for the delivery of major phospholipid components of endogenous lung surfactant. 

The mitochondrial respiratory parameters have also been employed to determine the toxicity of surfactants, including anionic (LAS), nonionic (NPEO) and their metabolites, sulfophenyl carboxylates (SPCs), NP and nonylphenoxy carboxylate (NPECi) [37]. The system employed was the in vitro response of submitochondrial particles from beef heart. The EC50 toxicity calculated as the reduction rate of NAD+ ranged from 0.61 mg L-1 for a commercial LAS mixture to 18 000 mg L-1 for SPCs, and 1.3 mg L-1, 8.2 and 1.8mgL 1 for NPEOio, NPECi and NP, respectively. These results indicate that from the toxicity perspective, LAS is the compound demanding increased attention, while for NPEO, the parental compound and the metabolites must be quantified. 

A sophisticated respiratory host defence system has evolved to clear airborne particles and potential pathogens in inspired air [106, 143], The system comprises mechanical (i.e. air filtration, cough, sneezing and mucociliary clearance), chemical (antioxidants, antiproteases and surfactant lipids) and immunological defence mechanisms and is tightly regulated to minimise inflammatory reactions [92, 143],... 

There are also several examples of natural surfactants and foams in the human body. The understanding of the pulmonary surfactant system, although discovered in 1929, has only been applied clinically since about 1990 for the treatment of respiratory distress syndrome. Surfactant replacement therapy may also be used in treating other forms of lung disease, such as meconium aspiration syndrome, neonatal pneumonia and congenital diaphragmatic hernia [881]. Lung surfactant, composed of phospholipids and proteins [882,883], is necessary to maintain a low surface tension at the alveolar air-liquid interface. When there is a deficiency of surfac-... 

Metered dose inhaler has been the most popular aerosol delivery device for the treatment of respiratory diseases, which is attributable to its portability and simple operation. Although seemingly easy to use, the MDI is a sophisticated device in design. The drug(s) are suspended or dissolved in a liquefied propellant system, which may also contain excipients such as cosolvents or surfactants. The formulation is kept pressurized in a small canister, sealed with a metering valve. Upon actuation through an actuator, the valve opens and the metered dose is dispensed as an aerosol spray from the expansion and vaporization of the propellant under ambient pressure. The inhalers may be used alone or with spacer devices, the electrostatic issues of which are considered in a later section. The present discussion focuses on the inherent charging of particles produced from MDIs. 

The delivery of aerosol powders by generation with minimal formulation has been an attractive prospect to many researchers. The early use of a dry powder artificial phospholipid in the treatment of neonatal respiratory distress syndrome proved very successful [181]. Because no delivery system was available to facilitate this treatment, a simple system was devised. A Laerdal neonatal resuscitation bag was modified to hold a capsule containing the artificial surfactant, as shown schematically in Fig. 11. However, where MDIs of the prescribed medication are available, both physicians and patients prefer their use. The powders themselves have to be prepared in the same way as those used in MDIs, by milling. Often, excipients are added to carry the fine powder. Lactose has been used in both cromolyn sodium and albuterol formulations. As a consequence of the interest in dry powders, a number of products have been... 

IV, subcut. human poison by ing. human systemic effects irritating to eyes, skin, respiratory tract corrosive can cause fatal poisoning absorbed thru skin target organs lungs, liver, kidneys possible mutagen experimental reproductive effects Precaution Hydrolyzed by alkalis inactivated by inert clays and anionic surfactants corrosive to metal... 

Phospholipids play an important role in lung functions. The surface active material to be found in the alveolar lining of the lung is a mixture of phospholipids, neutral lipids and proteins. Lowering of surface tension by the lung surfactant system and the surface elasticity of the surface layers assists alveolar expansion and contraction. Deficiency of lung surfactants in newborns leads to a respiratory distress syndrome and this led to the suggestion that instillation of phospholipid surfactants could cure the problem. 

Chem. Descrip. Dimethyipoiysiioxane and org. surfactants Uses Foam control agent in spraying systems Properties Wh. liq. mild odor emulsifiable in water sp.gr. 0.984 Toxicology Direct eye contact may cause temporary discomfort ing. of large amounts may cause digestive discomfort nonirritating to respiratory passages TSCA listed... 

Pulmonary epithelial cells have been extensively characterized as the producers of pulmonary surfactant lipid and protein species and in their role in the repair of epithelial damage through increased cell proliferation and subsequent differentiation. It is also clear that a subpopulation of the respiratory epithelium is capable of uptake, accumulation, and metabolism of inhaled and systemic lipophilic substances (89). 

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