Respiratory drugs antitussives

LJpper respiratory infections are among die most common afflictions of humans. The drug used to treat die discomfort associated widi an upper respiratory infection include antitussives, mucolytics, and expectorants. Many of tiiese dm are available as nonprescription (over-die-counter) dni, whereas otiiers are available only by prescription. 

Use of codeine may result in respiratory depression, euphoria, light-headedness, sedation, nausea, vomiting, and hypersensitivity reactions. The more common adverse reactions associated with the antitussives are listed in the Summary Drug Table Antitussive, Mucolytic, and Expectorant Drugs. When used as directed, nonprescription cough medicines containing two or more ingredients have few adverse reactions. However, those that contain an antihistamine may cause drowsiness. 

Expectorants are used to help raise respiratory secretions. An expectorant may also be included along with one or more additional drug, such as an antihistamine, decongestant, or antitussive, in some prescription and nonprescription cough medicines. 

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. 

Drug Analgesic Antitussive Constipation Respiratory depression ... 

It is a methyl ester of morphine and less potent analgesic than morphine. It is widely used as antitussive agent. Pholcodeine is also used as antitussive agent and causes less constipation (Details are given in chapter Drugs acting on respiratory system ). 

The drugs discussed in this chapter are used to control irritation and maintain airflow through the respiratory passages. Drugs such as the antitussives, deconges-... 

CODEINE In contrast to morphine, codeine is -60% as effective orally as parenteraUy as an analgesic and as a respiratory depressant. Codeine analogs such as levorphanol, oxycodone, and methadone have a high ratio of oral-to-parenteral potency. The greater oral efficacy of these drugs reflects lower first-pass metabolism. Once absorbed, codeine is metaboUzed by the liver, and its metabolites are excreted chiefly as inactive forms in the urine. A relatively small fraction (-10%) of administered codeine is O-demethylated to morphine, and free and conjugated morphine can be found in the urine after therapeutic doses of codeine. Codeine has an exceptionally low affinity for opioid receptors, and the analgesic effect of codeine is due to its conversion to morphine. However, its antitussive actions may involve distinct receptors that bind codeine itself. The tj of codeine in plasma is 2-4 hours. 

Age The popularity of codeine in pediatric anesthesia has been questioned [67 ]. Codeine is associated with a number of adverse events—constipation, nausea and vomiting, euphoria, itching, dry mouth, drowsiness, meiosis, urinary retention, hypotension, and respiratory depression. Intravenous codeine can cause profound hypotension and tonic-clonic seizures. It should be avoided in breast feeding. Using codeine concomitantly with other drugs, such as antitussives, can result in serious harm. Despite such evidence, codeine remains a popular choice. 

Noscapine or narcotine (3) is a phthalideisoquinoline alkaloid from plants of the Papaveraceae family. It is an important alkaloid from the opium poppy (Papaver somniferum L.), occurring in variable quantities (level ranges from 2% to 10%) [38]. Unlike opioid morphinane drugs, noscapine lacks hypnoanalgesic, euphoric, and respiratory depressant properties. Its main therapeutic application is as oral antitussive drug, which is indicated to treat nonproductive coughs [39, 40]. 

---