Vomiting dextromethorphan

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. 

Dextromethorphan should be used with great caution in individuals who have a history of chronic or persistent cough, persistent headache, nausea, vomiting, or fever. 

Contrary to the effects associated with the therapeutic use of dextromethorphan, those who abuse the drug report a variety of mind-altering effects such as visual hallucinations, changes in time perception, and an increased sense of perceptual awareness. It has been determined that a small amount of Robitussin can produce intoxication in most persons. Abusers have been found to use anywhere from one-half bottle to three or four bottles of Robitussin every day. Drinking large amounts of Robitussin or other cough syrups tends to cause vomiting. 

Emergency medical personnel should be contacted immediately if an overdose is suspected. If a poison control center suspects a dextromethorphan overdose, induced vomiting may be recommended. The usual home treatment involves the administration of ipecac syrup to induce vomiting. 

Morphi Dex contains morphine sulfate and dextromethorphan in a 1 1 ratio. Double-blind, single-dose analgesic efficacy studies in over 800 patients with post-surgical pain have shown superior analgesic activity for the combination (60 60 mg) than separate doses of the individual components (28,29). In double-bhnd, multiple-dose studies in 321 patients with chronic pain the combination provided satisfactory pain control with a significantly lower mean daily dose of morphine sulfate. Other studies have shown similar responses (28) and an adverse events profile similar to that of a similar dose of morphine sulfate (30). The most common adverse events seen in a multiple-dose, non-placebo-controlled study in 1400 subjects were nausea, dizziness, vomiting, somnolence, confusion, and pruritus. There was a significant trend toward lower incidence of constipation with the combination than with morphine sulfate alone (31,32). 

Adverse events are very uncommon with therapeutic doses (40-160 mg) however, dextromethorphan can cause some side effects such as dizziness, drowsiness, lightheadedness, nervousness, restlessness, nausea and vomiting, and stomach pain. 

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