Affecting the Respiratory System

UNIT V Drugs That Affect the Respiratory System... 

Unit V has three chapters concerning drugs that affect the respiratory system. The first chapter in this unit discusses antihistamines and decongestants, the second chapter in the unit covers bronchodilators and antiasthma drugs, and the last chapter of the unit deals with antitussives, mucolytics, and expectorants. 

Toxicology. Vanadium pentoxide primarily affects the respiratory system. 

Barbiturates are referred to as sedative-hypnotics. These drugs will induce sleep which can lead to even deeper sedation (hypnosis) and can cause a fatal depression of the RAS affecting the respiratory system. The sleep which is encountered does not have the normal cycles of slow wave and rapid eye movement activity, so it is not always restful. However, these agents prove to be useful in anesthesia for both short and longer durations of time. Many of you may have been given thiopental prior to wisdom tooth extraction. Thiopental "wears off quickly and so the actual anesthetic for the time of the extraction is usually nitrous oxide. 

Exposure to monochlorobenzene usually occurs by inhalation or skin contact. It is an irritant and affects the respiratory system, liver, skin, and eyes. Ingestion of this compound has caused incoordination, pallor, cyanosis, and eventual collapse, effects similar to those of aniline poisoning (see Section 15.3). Workers exposed to chlorobenzene have complained of headaches, numbness, sleepiness, and digestive symptoms, including nausea and vomiting. In general, most of these workers were exposed to other substances as well, so it is uncertain that their symptoms were due to chlorobenzene alone. 

One of the most common airborne suspensions known to affect the respiratory system adversely is tobacco smoke. The chemicals in tobacco smoke include a number of carcinogens, including nicotine and some of its derivatives, as well as poisonous gases including carbon monoxide and nitrogen dioxide. 

Summary of drugs affecting the respiratory system, described in Pharmacology update, pp. 450-451... 

Chapter 22 Update Drugs Affecting the Respiratory System 451... 

On I May 1981, in a district of Madrid in Spain, an 8-year-old boy died, apparently from a disease affecting the respiratory system. Later six more members of the family feU ill with similar symptoms. Other cases were reported at around the same time and within a few days the Directorate of Public Health became aware of the problem. This marked the beginning of an unusual outbreak of respiratory disease in and around Madrid. Within a week 150 or more cases per day were being recorded in various areas of Spain, and by June there were 2,000 cases in hospitals in Madrid. The outbreak rapidly became an epidemic, with over 10,000 cases being seen in hospitals in two months, and more than 20,000 cases were recorded by December 1982. There were a total of 351 fatalities. The iUness was widely reported and was so serious that the World Health Organization convened a conference in 1983. ... 

Symposium on Drugs Affecting the Respiratory System, 175th ACS Natl. Mtg., Anaheim, March, I978. 

The most important natural sources of minor tobacco alkaloids are from Nicotiana species, and at least eight minor tobacco alkaloids are shown in Figure 1. Since the chemical structures and physical properties of these minor tobacco alkaloids are similar to that of nicotine, some of them are shown to exhibit similar pharmacological activities as those of nicotine, although with a much lower potency. Table 2 shows their relative molar potency in some pharmacological systems. When nornicotine or anabasine was applied to the cat cervical ganglion, initial stimulation was followed by paralysis. On the autonomic ganglion and neuromuscular junction, nornicotine is only one-fifth to one-tenth as active as nicotine. Both nornicotine and anabasine have vaso-depressor action and affect the respiratory system. 

Increased doses of opioid analgesics also expose the patient to adverse side effects such as respiratory depression. Opioid analgesics can cause some respiratory depression. However, this effect usually does not occur with longterm use such as with cancer patients. Prescribers avoid this side effect by titrating doses over time to deliver pain relief without adversely affecting the respiratory system. 

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