Noscapin, cough

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

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. 

Noscapine is a naturally occurring product of the opium poppy. It is a benzylisoquinoline with no analgesic or other CNS effects. Its antitussive effects are weak, but it is used in combination with other agents in mixtures for cough relief. 

The opioid derivatives most commonly used as antitussives are dextromethorphan, codeine, levopropoxyphene, and noscapine (levopropoxyphene and noscapine are not available in the USA). They should be used with caution in patients taking monoamine oxidase inhibitors (see Table 31-5). Antitussive preparations usually also contain expectorants to thin and liquefy respiratory secretions. Importantly, due to increasing reports of death in young children taking dextromethorphan in formulations of over-the-counter "cold/cough" medications, its use in children less than 6 years of age has been banned by the FDA. Moreover, due to variations in the metabolism of codeine, its use for any purpose in young children is being reconsidered. 

Noscapine resembles papaverine in its action on smooth muscle and, in large doses, induces bronchodilation in animals. It is readily absorbed from the gastrointestinal tract, but its metabolic fate is unknown. In experimentally induced cough in animals and humans, noscapine exerts an antitussive action approximately equal to that of codeine, without any of the unpleasant side effects of codeine. It is administered orally in doses of 15 to 30 mg, three or four times daily as an antitussive. 

Many opiate analgesics are effective cough suppressants (also called anti-tussives), although only codeine and dihydrocodeine are generally used for this purpose. As there is a dissociation between the anti-tussive and analgesic action of the opiates, dextromethorphan and noscapine are now commonly used as cough suppressants because of their efficacy and lack of dependence-producing properties. 

Noscapine, which is derived from Papaver somniferum, has little analgesic or sedative effect. It is thought to be capable of modifying cough (1), but as with other anti-tussives, it remains difficult to say whether cough is genuinely suppressed or merely better tolerated. Headache and drowsiness can occur in a minority of patients and a skin rash has been occasionally reported. 

Fig. 7.15. Analysis of alkaloids in cough syrup after derivatization with dansyl-chloride2 Column Lichrosorb SilOO 10 wm (250x2.8 mm ID), mobile phase diisopropyl ether - isopropanol -cone, ammonia (48 2 0.3), detection UV 254 nm. Peaks 1, Dns-ephedrine 2, noscapine 3, Dns--cephaeline 4, Dns-emetine 5, codeine t, dodecylbenzene. Fluorescence detection witn excitation 360 nm and emission 500-510 nm.

The phytomedicines that inhibit the cough-centre Codeine, glaucine, noscapine and semisynthetic ethyphine. The phytomedicines that inhibit the cough-reflex Mucilaginous herbs such as Althea root and Icelandic moss. 

Noscapine is invariably employed in the control and management of cough due to bronchial asthma and pulmonary emphysema. It remakably reduces both the frequency and intensity of coughing paroxyms. Besides, it possesses weak bronchodilator actions and stimulates the respiration. It has no analgesie aetivity. 

Noscapine usually makes up 0.75—9% of opium alkaloids. It is found to exert a marked and pronounced action both on the frequeney as well as the intensity of the coughing paroxyms. 

Other nonnarcotic preparations include noscapine and levopropoxyphene, although their antitussive efficacy has not been proven. Levodropropizine, a nonopioid antitussive with peripheral inhibition of sensory cough receptors, has a favorable benefit-risk profile compared with dextromethorphan (Catena and Daffonchio 1997) this is currently available in several European countries. 

A number of medicines derived from opium are clinically very important. Morphine hydrochloride, purified from opium powder, is used as an analgesic and an anesthetic, and codeine phosphate and noscapine hydrochloride are used in cough medicines. Papaverine hydrochloride is used as a smooth muscle relaxant. 

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]. 

Opium poppy (Papaver somniferum), one of the oldest cultivated plants has been used in medicine since the beginning of civilization [221 ]. To date, it is the only commercial source of the narcotic drag morphine, the cough suppressant codeine and the antitumor agent noscapine. In addition to the substances mentioned above, poppy plants contain about eighty different... 

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