Dextromethorphan Cough suppressant

INTRODUCTION- This compound belongs to the class of organic compounds known as morphinans. These are polycyclic compounds with a four-ring skeleton with three condensed six-member rings forming a partially hydrogenated phenanthrene moiety, one of which is aromatic while the two others are alicyclic

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MECHANISM OF ACTION-

* Dextromethorphan is an opioid-like drug that binds to and acts as antagonist to the NMDA glutamatergic receptor, it is an agonist to the opioid sigma 1 and sigma 2 receptors, it is also an alpha3/beta4 nicotinic receptor antagonist and targets the serotonin reuptake pump. 

PHARMACOKINETICS-

* Dextromethorphan is rapidly absorbed from the gastrointestinal tract, where it enters the bloodstream and crosses the blood-brain barrier.

* The first-pass through the hepatic portal vein results in some of the drug being metabolized into an active metabolite of dextromethorphan, dextrorphan, the 3-hydroxy derivative of dextromethorphan.

HALF LIFE-3-6 hours

DRUG-DRUG INTERACTIONS-

* DEXTROMETHORPHAN+ ABIRATERONE= The serum concentration of Dextromethorphan can be increased.

* DEXTROMETHORPHAN+ ACEPROMAZINE= The risk or severity of adverse effects can be increased.

* DEXTROMETHORPHAN+  AMIODARONE=The metabolism of Dextromethorphan can be decreased.

SIDE EFFECTS-

* severe dizziness, anxiety, restless feeling, or nervousness;

* confusion, hallucinations; or

* slow, shallow breathing.

* Stomach upset

THERAPEUTIC USES-

* For the treatment of dry cough.

* It is  a cough suppressant. It affects the signals in the brain that trigger cough reflex.

REFERENCE: Tripathi K.D, "Essentials of medical pharmacology", Edition 7th, page no.-217, 220,221