ingredient information
Dextromethorphan Hydrobromide
Dextromethorphan (DXM or DM) is an antitussive (cough suppressant) drug. It is one of the active ingredients in many over-the-counter cold and cough medicines, such as Robitussin, NyQuil, Dimetapp, Vicks, Coricidin, Delsym, and others, including generic labels. Dextromethorphan has also found other uses in medicine, ranging from pain relief to psychological applications. It is sold in syrup, tablet, spray, and lozenge forms. In its pure form, dextromethorphan occurs as a white powder.[2] DXM is also used recreationally. When exceeding label-specified maximum dosages, dextromethorphan acts as a dissociative hallucinogen. Its mechanism of action is via multiple effects, including actions as a nonselective serotonin reuptake inhibitor[3] and a sigma-1 receptor[4][5] agonist and the action of its major metabolite dextrorphan as an NMDA receptor antagonist, producing effects similar to those of the controlled substances ketamine and phencyclidine (PCP),[6] as well as the active metabolite 3-methoxymorphinan, which produces local anesthetic effects in rats with a potency above dextrorphan but below dextromethorphan itself.[7] Contents [hide] 1 Medical use 2 Recreational use 3 Adverse effects 3.1 Contraindications 3.2 Drug interactions 3.3 Food interactions 3.4 Lab Testing 4 Chemistry 5 Pharmacology 5.1 Pharmacodynamics 5.2 Pharmacokinetics 5.3 Metabolism 6 History 7 See also 8 References 9 External links [edit] Medical useThe primary use of dextromethorphan is as a cough suppressant, for the temporary relief of cough caused by minor throat and bronchial irritation (such as commonly accompanies the flu and common cold), as well as those resulting from inhaled irritants.[citation needed] A 2004 study showed that dextromethorphan was no more effective for children than a placebo.[8] Studies conducted by the American Academy of Pediatrics show that dextromethorphan is not superior to a placebo in providing nocturnal symptom relief for children with cough and sleep difficulty due to upper respiratory infections.[9] In addition, a combination of dextromethorphan and quinidine has been shown to alleviate symptoms of easy laughing and crying (pseudobulbar affect) in patients with amyotrophic lateral sclerosis and multiple sclerosis.[10] Dextromethorphan is also being investigated as a possible treatment for neuropathic pain and pain associated with fibromyalgia.[11] On October 29, 2010 The FDA approved the combination product (Nuedexta) manufactured by Avanir pharmaceutical corporation for the treatment of pseudobulbar affect (PBA). [edit] Recreational use Dextromethorphan gel capsulesMain article: Recreational use of dextromethorphan Since their introduction, over-the-counter preparations containing dextromethorphan have been used in manners inconsistent with their labeling, often as a recreational drug.[12] At doses higher than medically recommended, dextromethorphan is classified as a dissociative hallucinogen. Certain effects that are similar to the dissociative agents ketamine and phencyclidine (PCP). It can produce distortions of the visual field - feelings of dissociation, distortions of bodily perception, excitement, as well as a loss of sense of time. Some users report stimulant-like euphoria. Dextromethorphan usually provides its recreational effects in a non-linear fashion, so that they are experienced in significantly varied stages. These stages are commonly referred to as "plateaus." [13][14][15] [edit] Adverse effectsSide-effects of dextromethorphan use can include:[16] At normal doses: Sudden infant death syndrome [17] body rash/itching (see below) nausea drowsiness dizziness Closed-eye hallucination Difficulty breathing At dosages 12.5 to 75 times the recommended therapeutic dose: hallucinations disassociation vomiting blurred vision bloodshot eyes dilated pupils sweating fever bruxia hypertension shallow respiration diarrhea urinary retention Dextromethorphan can also cause other gastrointestinal disturbances. Dextromethorphan had been thought to cause Olney's Lesions when administered intravenously; however, this was later proven inconclusive, due to lack of research on humans. Tests were performed on rats, giving them 50 mg and up every day up to a month. Neurotoxic changes, including vacuolation, have been observed in posterior cingulate and retrosplenial cortices of rats administered other NMDA antagonists such as PCP, but not with dextromethorphan.[18][19] In many documented cases, dextromethorphan has produced psychological dependence in people who used it recreationally. However, it does not produce physical addiction, according to the WHO Committee on Drug Dependence.[20] [edit] ContraindicationsBecause dextromethorphan can trigger a histamine release (allergic reaction), atopic children, who are especially susceptible to allergic reactions, should be administered dextromethorphan only if absolutely necessary, and only under the strict supervision of a healthcare professional.[16] [edit] Drug interactionsDextromethorphan should not be taken with Monoamine oxidase inhibitors (MAOIs)[16] or Serotonin reuptake inhibitors (like SSRIs and SNRIs)[16] due to the potential for serotonin syndrome, which is a potentially life-threatening condition that can occur rapidly, due to a buildup of an excessive amount of serotonin in the body.[citation needed] [edit] Food interactionsCaution should be exercised when taking dextromethorphan when drinking grapefruit juice or eating grapefruits, as compounds in grapefruit affect a number of drugs, including dextromethorphan, through the cytochrome p450 system in the liver. [edit] Lab TestingTesting for this drug is done either by blood or by urine. Blood can be either serum or plasma, serum in a plain red top 2mL preferred. Urine requires only 2mL minimum. [edit] ChemistryDextromethorphan is the dextrorotatory enantiomer of levomethorphan, which is the methyl ether of levorphanol, both opioid analgesics. It is named according to IUPAC rules as (+)-3-methoxy-17-methyl-9a,13a,14a-morphinan. As the pure free base, dextromethorphan occurs as an odorless, white to slightly yellow crystalline powder. It is freely soluble in chloroform and insoluble in water. Dextromethorphan is commonly available as the monohydrated hydrobromide salt, however some newer extended-release formulations contain dextromethorphan bound to an ion exchange resin based on polystyrene sulfonic acid. Dextromethorphan's specific rotation in water is +27.6° (20 °C, Sodium D-line).[citation needed]