Respiratory airways

Chemicals have to pass through either the skin or mucous membranes lining the respiratory airways and gastrointestinal tract to enter the circulation and reach their site of action. This process is called absorption. Different mechanisms of entry into the body also greatly affect the absorption of a compound. Passive diffusion is the most important transfer mechanism. According to Pick s law, diffusion velocity v depends on the diffusion constant (D), the surface area of the membrane (A), concentration difference across the membrane (Ac), and thickness of the membrane (L)... 

Continuous, coarse, whistling sound produced in the respiratory airways during breathing when air flow becomes accelerated through narrowed or obstructed airways. 

Bell, K.A. (1978). Local particle deposition in respiratory airway models. In Recent Developments in Aerosol Science (Shaw, D.T., Ed.). Wiley New York, pp. 97-134. 

Kliment, V. Dichotomical model of respiratory airways of the rabbit and its significance for the construction of deposition models. Folia Morphol. 22 286-290, 1974. 

Toxicology. Nitrogen mustards are vesicants and alkylating agents that damage the respiratory airways and cause skin and eye burns. 

Coughing is a refiex action, or involuntary movement, in which the body tries to expei foreign materiai (such as dust, a bug, or excess mucus secretions) from the respiratory airways (specificaiiy the trachea, or windpipe, and the bronchi, also called bronchial tubes, of the lungs.)... 

This is also referred to as the upper airways , which includes the respiratory airways from the nose down to the larynx. This region has been described extensively in Chapter 9. 

Bioavailability from Environmental Media. No studies were located regarding the bioavailability of acrolein from environmental media. Since acrolein has been detected in ambient air and in food and beverages (ppb levels), it is important to determine if acrolein can be absorbed by humans from environmental samples. However, the chemical structure of acrolein makes it a highly reactive molecule, which presumably is why its effects are, for the most part, restricted to the area of exposure (i.e., respiratory system for inhalation exposure or localized skin damage for dermal exposure). The limited information available regarding absorption parameters of acrolein in experimental animals indicates that acrolein is easily retained in the respiratory airways however, virtually no information is available regarding absorption by the gastrointestinal tract or skin. Therefore, based on the data available, it is likely that inhalation of contaminated air will result in irritation of the eyes and respiratory tract. 

Advances in aerosol generation technology, which provide more efficient and controlled delivery of aerosolized pharmaceutical compounds into the human respiratory airway ... 

Using aerosolization to administer drugs to the respiratory airway dates back to the early part of the 20th century, when the pneumatic nebulizer was used as a drug delivery device. Fig. lA shows some examples of the first types of nebulizers used, the simplest of which were powered by squeezing the bulb attached to the device. Fig.IB shows more modern imits such as pMDIs. 

Deposited dose The amount of drug deposited in the respiratory airways, which can further be divided into the drug amount in the oropharyngeal region and lungs... 

Advantages and disadvantages of the ultrasonic nebulizer for the delivery of pharmaceutical compounds to the human respiratory airways are listed in Table 8. The output of drug compound leaving the ultrasonic nebulizer is at a relatively slow velocity compared with the jet nebulizer. Therefore, less patient coordination is required during treatment. 

The selection of a drug delivery system suitable for the administration of a particular drug compound to human respiratory airways depends not only on the device performance, but also on many other factors such as drug properties, formulation excipient, intended site of action, marketing preference, and regulatory requirements. It is important to fully understand the drug properties during the formulation... 

The efficacy of a therapeutic inhalation aerosol depends onits ability to penetrate the respiratory tract. This is primarily dependent on the particle size of the particles or droplets. To penetrate to the peripheral (respiratory) airways, aerosols generally require a size less than approximately 5-6 pm, with a size less than 2 pm being optimal for alveolar deposition. " ... 

Parvolex ) is used a MUCOLYTIC agent, which reduces the viscosity of sputum, so can be used as an expectorant in patients with disorders of the upper respiratory airways, such as chronic asthma and bronchitis. It is also used orally to treat abdominal complications associated with cystic fibrosis, and locally in the eye to increase lacrimation and mucus secretion. It is also used intravenously as an antidote in paracetamol poisoning. 

The various levels of the airways may be categorized functionally as being either conducting or respiratory airways. Those airways not participating in gas... 

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