Cough suppression

Alkaloids range from the belladonna alkaloids, such as atropine and scopalomine—which are used as poisons, cold remedies, and truth serums —to dextromethorphan, a cough suppressant (anti-tussive). But the most widely known alkaloids are the opiates, such as morphine, heroin, fentanyl, oxycodone, and methadone. These act on... 

There are two chiral centres In (47) so a mixture of diastereoisomers is produced in 75 and 15% yields. Fortunately the major isomer is the analgesic. In fact only one enantiomer of this diastereo isomer is analgesic and so (48) is resolved with camphor sulphonic acid before esterification. The other enantiomer is a useful cough suppressant. 

Analgesia Relief of anxiety Euphoria Nausea Constipation Cough suppression Dependence Similar to mu but less marked Analgesia Aversion Diuresis Analgesia Hyperalgesia... 

The large numbers of opioid receptors in areas of the brainstem such as the solitary tract and adjacent areas are probably related to respiratory effects of opiates, cough suppression and nausea and vomiting. Opiates acting in the brainstem reduce the sensitivity of the respiratory centres to pC02 and this is the most common cause of death from overdose with street use of opiates. 

Opiates activate the chemoreceptor trigger zone in the medulla (by disinhibition) to cause nausea and vomiting, and cough suppression also occurs because of the inhibitory effects of opiates on the brainstem nuclei in the cough reflex pathway. Dextromethorphan is the non-opiate isomer of the opiate levorphanol and is an effective cough suppressant. 

Another potential benefit of UHPLC is its capability of solving the most challenging separation tasks in pharmaceutical analysis. Figure 9.4 shows a UPLC method developed to analyze pharmaceutical formulations used to treat the common cold. Cold products often contain multiple active ingredients to treat different symptoms and can contain decongestants, antihistamines, pain relievers, cough suppressants, expectorants, and numerous excipients of various polarities. The analysis of a total of 20 components was achieved within 10 min. 

In addition, morphine has served as a point of departure for the discovery of many medically usefnl derivatives. These inclnde codeine, a pain reliever and cough suppressant, levophanol, an orally active analgesic (morphine is not active when given orally and is nsnally given by injection), and many other modem and highly potent opiate analgesics. 

Codeine, dextromethorphan and pholcodine are opioid cough suppressants indicated for dry cough. Sedating antihistamines, such as diphenhydramine, tend to have an antitussive action as well. Vitamin C is not used in the management of cough but may be used as a prophylaxis against colds. 

Dextromethorphan is an opioid antitussive similar in action to codeine and pholcodine. Codeine and pholcodine are considered to be more potent than dextromethorphan. Dextromethorphan tends to cause less constipation and dependence than codeine. Cough suppressants are not usually recommended in children under 2 years. 

The same type of reasoning allows production of pholcodine, an effective cough suppressant, from morphine. In this semi-synthesis, the electrophile is Ai-(chloroethyl)morpholine, and the leaving group is chloride. 

The cough-suppressant (antitussive) effect produced by inhibition of the cough reflex is independent of the effects on nociception or respiration (antitussives codeine, noscapine). 

Hydrocodone is an opium analgesic (pain reliever) and antitussive (cough suppressant). It is related in structure to other alkaloids used as drugs, such as morphine and codeine (see Section 8). It increased 20% in number of prescriptions for one year. Its synthesis from codeine is by simple reactions. 

Codeine occurs naturally in opium but the amount is too small to be useful. It is prepared from morphine by methylating the phenolic hydroxyl group with diazomethane, dimethyl sulfate, or methyl iodide. Codeine does not possess the same degree of analgesic potency as morphine but is used as an antitussive, a cough suppressant. Hydrocodone was discussed in Section 3.4. It is made from codeine. 

Pharmacology Dextromethorphan is the d-isomer of the codeine analog of levorphanol. Its cough suppressant action is due to a central action on the cough center in the medulla. Dextromethorphan 15 to 30 mg equals 8 to 15 mg codeine as an antitussive. 

Alkaloids such as boldine, codeine, narceine and morphine are active factors in their receptors. Boldine has morphine-like properties and is active on opioid receptors. It may be used to treat stomach disorders and as metabolic stimulant. As it is similar to morphine, boldine can also be considered in the possible development of treatments for narcotic dependence. Codeine also binds to opiate receptors, and specifically functions to reduce bronchial secretions. Codeine can also be used as a cough suppressant when acting on the centre of the medulla oblongata and as a sedative agent. 

Ephedrine is the main alkaloid produced in the roots of Ephedra sinica, preparations of which have found medical application in China for at least 5000 years. It was first purified from its natural source in 1887, and its chemical synthesis was achieved in 1927. It was initially used in cardiovascular medicine, but subsequently found wider application in the treatment of mild hayfever and asthma. It is also used as a nasal decongestant and cough suppressant. 

Cough may be dry or productive. A centrally acting cough suppressant can be tried in dry cough first choice treatment is noscapine which is safer and has less adverse reactions than codeine and ethyl morh-pine. 

Codeine is a close chemical relative of morphine, differing in only one chemical group. Once administered, codeine is actually metabolized by enzymatic action, and its actions mimic those of morphine. Codeine is used primarily as a cough suppressant, although it certainly also possesses significant analgesic properties (approximately one tenth those of morphine) as in the relief of pain from toothache. 

Noscapaine has only minimal therapeutic and narcotic properties. It can be used as a cough suppressant, but has no apparent advantage over other agents. 

Codeine is a natural alkaloid found in the opium plant. As a pharmaceutical, codeine is used as an analgesic, antitussive, and antidiar-rheal. Codeine is also commonly combined with other cough suppressants as well as with aspirin and ibuprofen. In the United States, codeine is a Schedule III controlled substance, which means that its distribution is more tightly regulated than unscheduled drugs. Codeine has pain-relieving qualities principally because, once in the body, about 10 percent of codeine turns into morphine. This conversion occurs in the liver, where an enzyme changes codeine s... 

---