Inhalants dependence mechanisms

Chlorine inhalational damage is not restricted to particular cell types, such as epitiielial cells. Injury caused by inhaled chlorine can be complex and involves multiple pathways (Figure 36.1). The loss of vascular tone following chlorine exposure has been linked to dysfunctional nitric oxide (NO)-dependent mechanisms and resulting vasodilation (Honavar et al., 2011). To address the role of NO, Honavar et al. (2014) found that when rats were exposed to a total chlorine concentration of 12,000 ppm X min, isolated pulmonary artery studies showed disruption of vascular tone due to disrupted NO signaling. The balance between endothelial nitric oxide synthase (eNOS)- and inducible nitric oxide s)mthase (iNOS)-derived NO was disrupted by chlorine. The expression and activation of eNOS and iNOS... 

Inhaled gaseous compounds are absorbed in all parts of the respiratory system whereas particle size determines how deep into the airways the parti cles will he transported in the airstrearn. Shortness of breath is a typical sign of a chemical exposure that has affected the lungs, and it may be evoked through iminunological mechanisms (e.g., formaldehyde, ethyleneoxide), or through toxic irritation (formaldehyde, isocyanates, sulfur dioxide, nitrogen dioxide, Frequently the mechanism depends on the concentration ol the com... 

Asphyxiants interfere with the body s oxygen uptake mechanisms. Air normally contains 21% oxygen. Oxygen deficiency in inhaled air, e.g. due to the presence of nitrogen, argon, or carbon dioxide in a confined space, depending on the concentration and duration, may affect the body and ultimately cause death from simple anoxia (Table 4.7). 

Dusts may carry chemicals into the lungs, where they can be absorbed by several mechanisms. But there are other physical materials - asbestos is the most well known - that, depending upon their physical dimensions, can also be inhaled and can move down the respiratory tract to the lung, where they can reside in insoluble form for long periods of time and cause serious, lasting damage. 

What can be expected in the near and middle future for inhaled powder delivery There certainly will be some more new passive devices to reach the market and the patient, but it seems that a lot of purely mechanical design ideas have been implemented already in the newest generation of multiple-dose DPIs. Most important are audible and visible feedback features that help to improve delivery efficiency and patient compliance. Future improvements also seem possible in reducing dependency of the particle dispersion on actuation flow rate and internal device resistance. The next or over-next generation of multiple-dose devices also may incorporate lean, inexpensive, but rugged electronics... 

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