Misuse of the cough suppressant dextromethorphan hydrobromide is "limited and episodic" and is "not gaining popularity," Whitehall-Robins tells FDA in a Jan. 19 submission. The firm's letter and attached materials relate to a MedWatch adverse event report detailing the Oct. 13 death of a 23-year-old man who "committed suicide by hanging after probably having ingested a DM-containing product."

Whitehall markets dextromethorphan-containing Robitussin DM, listed in the MedWatch report as the "suspect medication." The report also notes the man "had obtained a powdered form of dextromethorphan via the Internet several times within the past year."

Other Robitussin products contain the ingredient, as do many other companies' OTC cough/cold products.

The victim, a "long-time known abuser of dextromethorphan (DM) containing cough medicines," also had been diagnosed with bipolar disorder, but it was unknown whether he was being "treated for this or any other medical problem at the time of his death."

The man's death was "attributed to strangulation and decedent was known to have threatened suicide several times in the past," the report says. Sixty-four deaths reported to MedWatch between 1969 and January 1999 have listed dextromethorphan as one of the top four substances taken by the deceased.

In an attachment to its letter, entitled "Current Status Review: Dextromethorphan Abuse," Whitehall says "diligent research and surveillance of several information resources, including published literature, selected databases and Internet sites concerning substance abuse, indicate that dextromethorphan misuse is a limited and sporadic event."

"Dextromethorphan abuse has the characteristics of a fad, in that the abuse starts with a few individuals, gains brief popularity and rapidly dwindles," the company says.

"Even with the rapid and extensive growth of the Internet, which permits ideas to be broadcast to a much larger audience than was previously possible, there is no evidence that the rate of abuse has increased."

In previous instances, retailers have responded to dextromethorphan product abuse and related shoplifting by removing the products from shelves and stocking the products behind the pharmacy counter.

In 1991, Whitehall launched Robitussin DM in unit-dose vials, six to a pack - ostensibly for the sake of convenience, but also perhaps with the idea of making it more difficult to ingest unsafe amounts of the product.

To "determine the nature and extent" of abuse of the cough suppressant, Whitehall "monitors published literature, media reports and legislative activity for new information concerning medical and epidemiological aspects of dextromethorphan" and "performs an ongoing, internal post-market surveillance program" for all Whitehall-Robins products containing the ingredient.

The company also "monitors Internet newsgroup postings and Web sites that involve dextromethorphan misuse" and "analyzes statistical data" from HHS.

Weekly literature searches do "not indicate a change in the nature or increase in frequency of dextromethorphan misuse," the company says. "The volume of articles on misuse is a minor fraction of the dextromethorphan articles published."

Whitehall's adverse event surveillance indicates that since January 1997, four of 127 AE reports for the cough/cold ingredient "involved intentional overdose."

"All four patients were male," Whitehall says, noting one was 20, two were 25 and one was 40. "Of the four abusers, one was a habitual drug abuser, one was counseled for drug abuse and one was undergoing psychiatric evaluation." Three reports contained other AEs, including depression, hallucinations and diarrhea.

The company's Internet monitoring indicates the "quantity of postings and Web sites appears to be steady, if not decreasing." The "majority of postings describe personal overdose experiences" and a "great number of people who have submitted messages to the newsgroups have multiple postings," the firm says.

Whitehall notes the "issue of DM abuse has been reviewed extensively in the past." The company submitted data on abuse of the ingredient in July 1990 and March 1992 for respective August 1990 and July 1992 meetings of FDA's Drug Abuse Advisory Committee.

At both meetings, committee members commented on the need for more data relating to the incidence of abuse of the cough suppressant ingredient. Whitehall says "review of the deliberations of these advisory committees indicate[s] a decision that community education and monitoring was in order. Further action was only deemed necessary if an increase in frequency or scope of DM abuse occurred."

In its January submission to FDA, Whitehall also notes data from the Drug Abuse Warning Network survey (DAWN) and the Monitoring the Future Survey (MTFS) "indicate dextromethorphan abuse is relatively insignificant when compared to other forms of drug abuse."

DAWN data from 1995 indicate "dextromethorphan ranked number 28 of 74 on the list of drugs most frequently mentioned by medical examiners with a total of 88 reports, equaling .95% of total episodes reported."

"By comparison, acetaminophen and aspirin, drugs not usually considered to be drugs of abuse, with 367 reports (4%) and 105 reports (1.1%), respectively, are nonprescription drugs with a greater number of reports than dextromethorphan." Cocaine accounted for 45.6% of all episodes, "alcohol-in-combination" for 39.2% and diphenhydramine, 5%.

"DAWN's Annual Emergency Department Data for 1994...which contains drugs mentioned most frequently in emergency departments, did not mention dextromethorphan (drugs with less than 200 weighted measurements were excluded)," Whitehall says.

"Nonprescription drugs included on the list are pseudoephedrine and chlorpheniramine products (alone or in combination), phenylpropanolamine, acetaminophen, aspirin, diphenhydramine, brompheniramine and OTC diet aids," Whitehall points out. Dextromethorphan also was not included in the 1997 MTFS list of drugs being misused by students, the firm notes.

At the 1992 advisory committee meeting, former FDAer Curtis Wright, MD, then a reviewer in the agency's Pilot Drug Evaluation Staff, commented that usual methods of drug abuse surveillance "strike out with this agent," adding "medical examiner mentions aren't very good," and "emergency room visits and the DAWN system aren't very good" either.

Dextromethorphan Abuse "Not Gaining Popularity," Whitehall-Robins Says

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