Drugs and Chemicals of Concern

DEXTROMETHORPHAN
(Street Names:  DXM, CCC, Triple C, Skittles, Robo, Poor Man’s PCP)

August 2010
DEA/OD/ODE

Introduction:

Dextromethorphan (DXM) is an over-the-counter (OTC) cough suppressant found in cold medications.  DXM is often abused in high doses by adolescents to generate euphoria and visual and auditory hallucinations.  Illicit use of DXM is referred to on the street as “Robo-tripping” or "skittling."  These terms are derived from the most commonly abused products, Robitussin and Coricidin.

Licit Uses:

DXM is an antitussive found in more than 120 OTC cold medications either alone or in combination with other drugs such as analgesics (e.g. acetaminophen), antihistamines (e.g. chlorpheniramine), decongestants (e.g. pseudoephedrine) and/or expectorants (e.g. guaifenesin).  The typical antitussive adult dose is 15 or 30 mg taken three to four times daily.  The antitussive effects of DXM persist for 5 to 6 hours after oral administration.  When taken as directed, side-effects are rarely observed.  IMS Health™ reports a decrease in total dispensed prescriptions of DXM from 17.6 million in 2005 to 14.9 million in 2009.

Illicit Use:

The abuse of DXM is fueled by its OTC availability and extensive “how-to” abuse information on various web sites.  The sale of the powdered form of DXM over the Internet poses additional risks due to the uncertainty of composition and dose.

DXM abusers report a heightened sense of perceptual awareness, altered time perception, and visual hallucinations. The typical clinical presentation of DXM intoxication involves hyperexcitability, lethargy, ataxia, slurred speech, sweating, hypertension, and/or nystagmus.  Abuse of combination DXM products also results in health complications from the other active ingredient(s), which include increased blood pressure from pseudoephedrine, potential delayed liver damage from acetaminophen, and central nervous system toxicity, cardiovascular toxicity and anticholinergic toxicity from antihistamines.  The abuse of high doses of DXM in combination with alcohol or other drugs is particularly dangerous and deaths have been reported.

Abusers of DXM describe four dose-dependent “plateaux:”

According to the American Association of Poison Control Centers, there were 52,991 case mentions and 40,229 single exposures related to DXM in 2008.The Drug Abuse Warning Network (DAWN ED) reports that an estimated 7,739 emergency department visits were associated with non-medical use of dextromethorphan in 2006, 10,410 visits in 2007 and 7,988 visits in 2008.

Chemistry/Pharmacology:

DXM (d-3-methoxy-N-methyl-morphinan) is the dextro isomer of levomethorphan, a semisynthetic morphine derivative.  Although structurally similar to other narcotics, DXM does not act as an opioid receptor agonist (e.g. morphine, heroin).  DXM and its metabolite, dextrorphan, act as potent blockers of the N-methyl-d-aspartate (NMDA) receptor.  At high doses, the pharmacology of DXM is similar to those of the controlled substances phencyclidine (PCP) and ketamine that also antagonize the NMDA receptor.  High doses of DXM produce PCP-like behavioral effects.  DXM may cause a false positive test result with some urine immunoassays for PCP.

Approximately 5-10% of Caucasians are poor DXM metabolizers which increases their risk for overdoses and deaths. DXM should not be taken with antidepressants due to the risk of inducing a life threatening serotonergic syndrome.

User Population:

Abuse of DXM occurs in all age groups but is most prevalent in youth and adolescents.  A 6-year retrospective study from 1999 to 2004 of the California Poison Control System (CPCS) showed a 10-fold increase in the rate of CPCS DXM abuse cases in all ages and a 15-fold increase in the rate of CPCS DXM abuse cases in adolescents.  In 2004, CPCS reported 1,382 DXM abuse cases.
The 2009 Monitoring the Future (MTF) Report indicated that the annual prevalence of non-medical use of cough and cold among students in 8th, 10th, and 12th grades was 2.6%, 5.0%, and 6.3%, respectively.

DAWN ED reports that, in 2004, the rate of ED visits resulting from nonmedical use of DXM for those aged 12 to 20 was 8.0 visits per 100,000 population, compared with 2.5 visits or fewer per 100,000 for other age groups.

Illicit Distribution:

DXM abuse often occurs with the OTC liquid cough preparations.  More recently, abuse of tablet and gel capsule preparations has increased.  DXM powder sold over the Internet is also a source of DXM for abuse.  DXM is also distributed in illicitly manufactured tablets, containing only DXM or mixed with other illicit drugs such as ecstasy or methamphetamine.
According to the National Forensic Laboratory Information System (NFLIS) and the System to Retrieve Information from Drug Evidence (STRIDE), federal, state and local forensic laboratories analyzed 190 dextromethorphan exhibits that were submitted in 2008 and 279 exhibits that were submitted in 2009.

Control Status:

DXM is not scheduled under the Controlled Substances Act (CSA).  However, the CSA indicated that DXM could be added to the CSA, in the future, through the traditional scheduling process, if warranted.

Comments and additional information are welcomed by the Drug and Chemical Evaluation Section; Fax 202-353-1263, telephone 202-307-7183 or Email ODE@usdoj.gov.