Dextromethorphan abuse is increasing slightly, but the problem is not widespread, according to FDA. One expert notes the extent might not justify scheduling the cough suppressant as a controlled substance.

At a meeting Sept. 14, FDA will ask the Drug Safety and Risk Management Advisory Committee to assess the extent of DXM abuse and whether the popular OTC ingredient should be a controlled substance (see ¹ Also see "FDA Panel To Weigh DXM Education, Sales Restrictions Against Scheduling" - Pink Sheet, 6 September, 2010. ).

In briefing materials prepared for the meeting, FDA notes data from the Drug Abuse Warning Network reveal emergency department visits nationwide related to non-medical use of single ingredient DXM products increased 32 percent from 1,163 in 2005 to 1,536 in 2008.

"However, it does not indicate that DXM products are widely abused," FDA notes.

Researchers with the Center for Drug Evaluation and Research Office of Surveillance and Epidemiology say per 10,000 bottles of single-ingredient DXM sold in 2008, there were 1.5 emergency department visits related to abuse - down slightly from 1.6 the previous year.

The abuse ratio for DXM in 2008 is significantly lower than the 2.4 visits per 10,000 bottles sold of diphenhydramine - the active ingredient in Benadryl - and only slightly higher than the 0.8 abuse rate for the decongestant pseudoephedrine, the CDER researchers say.

The agency acknowledges that the data do not accurately reflect the full extent of DXM abuse because they do not include abuse of combination products that contain DXM or incidents that do not result in emergency department visits or death.

Combination products make up the majority of DXM-containing products available OTC, but many people who abuse DXM seek single-ingredient formulas so as not to suffer unwanted side effects from other ingredients like acetaminophen, according to FDA's materials.

Other studies capture the abuse of combination products and incidents that do not lead to emergency department visits.

The University of Michigan's annual Monitoring the Future survey tracks self-reported abuse of cough and cold products by grade-schoolers. It found 2.6 percent of 8 graders, 5 percent of 10 graders and 6.3 percent of 12 graders reported using cough and cold medicines for non-medical use in 2009. This is flat compared to 2008, according to background materials submitted by the Drug Enforcement Administration and the Consumer Healthcare Products Association.

In 2008, though, the crude number of all adverse events related to DXM abuse peaked sharply, with 107 abuse reports including 45 deaths, according to FDA data.

FDA attributes the increase in abuse to the drug's low cost, easy availability via OTC status, lack of suspicion and the perception that OTC products are safe.

Based on these motivators and the prevalence of intentional overdosing, FDA adds "routine labeling changes or product packaging redesign will probably not reduce the present abuse trend."

On the other hand, scheduling DXM as a controlled substance would eliminate OTC access, likely increase the price and ostensibly alter consumers' perception of the drug's safety.

Drug Abuse Serious, But Limited

While DXM abuse is a serious problem, the data might not justify an action as drastic as scheduling DXM as a controlled substance, said Randy Juhl, vice chancellor for research conduct and compliance at the University of Pittsburgh and one-time chair of the FDA Nonprescription Drug Advisory Committee. NDAC will not participate in the Sept. 14 meeting (² Also see "Wolfe Absence May Have Disarming Effect On DXM Safety Panel" - Pink Sheet, 30 August, 2010.).

"The risk doesn't seem all that great" considering people take millions of doses, he said. He added he "wasn't real impressed by the data showing the number of emergency room visits or poison control visits" due to DXM abuse.

DEA cites a 201 percent increase in dextromethorphan "exhibits" from 88 in 2003 to 265 in 2006, according to data from the National Forensic Laboratory Information System and the System to Retrieve Information From Drug Evidence.

However, Juhl said that DEA "just happened to pick a low year to start with and a high year to end, but if you look at the data in between it is not too remarkable."

Indeed, the data range from 33 incidents in 2003 to 161 in 2004, 223 in 2005, 147 in 2006 and 128 in 2007 before settling on 186 in 2008.

"There is no big increase in abuse. There might be a light increase," Juhl said before acknowledging, "There is no decrease in abuse either."

The abuse rates remain relatively flat in part because half of the children who abused cough and cold medicine say they would not do it again because they say "the high is lousy," said Steve Pasierb, president and CEO of Partnership for a Drug-Free America

Pasierb also attributes the flat DXM abuse rate to education campaigns launched seven years ago when DXM abuse started rising.

PDFA worked with CHPA to create online education tools aimed at potential abusers who research the drug before taking it. The campaign raised awareness of the risks and helped boost social disapproval, he said.

Pasierb also argues education is more effective than scheduling because children tend to abuse Rx drugs.

"When it comes to a 13-year-old, scheduling doesn't matter in his or her world. We know that kids say they have no problem getting some very, very strong prescription drugs," he said, adding he addresses prescription drug abuse by children "day in and day out."

Another option that might reduce abuse more effectively than scheduling is to restrict sales of bulk DXM to only manufacturers, pharmacists and researchers, Pasierb said.

He explained users on the internet promote buying the bulk ingredient, or "pure" DXM, as a safer more effective way to get high. If it was not available, fewer people might abuse it.

- Elizabeth Crawford ( ³ e.crawford@elsevier.com )

Extent Of DXM Abuse May Not Support Scheduling

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