Enkephalinomimetic drugs - Antitussive and antidiarrheal agents
Antitussive agents
A certain number of morphine derivatives such as codeine, codethyline also called ethylmorphine, dextromethorphan, noscapine, pholcodine are used as antitussive agents. In proprietary formulations, these morphine derivatives are often combined with various compounds of vegetable origin, considered as pulmonary disinfectants.
Many cough suppressants considered as non opioid are not marketed any more. However, one of them clobutinol is available in many countries
Cough can be the symptom of a disease requiring diagnosis or the mean of ensuring expectoration. In these two cases, its treatment is useless and is not advised. Only non-productive, dry, irritating coughs deserve a prescription.
Antidiarrheal
The antidiarrheal morphine drugs, by decreasing digestive secretions and by slowing down transit, constitute a supportive care for acute and chronic diarrhea. They do not exempt from possible etiological treatment, anti-infectious, antifungal for example.
Powdered analogues of opium were very much used under the name of paregoric elixir.
Currently, powdered opium is replaced by synthetic opioid analogues such as diphenoxylate and loperamide,. Loperamide, Imodium*can also be given in oxide form which is gradually converted during its digestive transit into loperamide. Loperamide oxide is less absorbed by the digestive tract than loperamide itself.
Racecadotril, previously called acetorphan, is an indirect morphinomimetic which inhibits enkephalinases and increases enkephalin concentration in the digestive tract, reducing intestinal secretions. But because it hardly crosses the blood-brain barrier it has no central effect. It is indicated in the supportive care of diarrhea.
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