NCIt definition : A synthetic, methylated dextrorotary analogue of levorphanol, a substance related
to codeine and a non-opioid derivate of morphine. Dextromethorphan exhibits antitussive
activity and is devoid of analgesic or addictive property. This agent crosses the
blood-brain-barrier and activates sigma opioid receptors on the cough center in the
central nervous system, thereby suppressing the cough reflex.;