The IMS data represent one of the most comprehensive sources available to track retail prescription medication sales at the national level. Nevertheless, the data have limitations. Because they are prescription-level data, the number of users for each medication and their adherence to the medication regimen are unknown. IMS data do not include information on the diagnosis for which the prescriptions were written, and it is possible that some of the prescriptions included in this analysis were for non-substance dependence conditions. Moreover, other medications, not included in this analysis, are used “off-label” to treat substance use disorders.
The data indicate that sales and prescriptions for medications to treat alcoholism and opioid dependence grew rapidly following the introduction of new medications. In the alcoholism medications market, the acceptance and use of acamprosate caused overall alcoholism medication sales to approximately double from 2002 to 2007. The introduction of a long-acting formulation of naltrexone and of acamprosate may have spurred an increase in oral naltrexone prescriptions, which had previously remained relatively steady. Buprenorphine sales grew even more rapidly and exceeded those of alcoholism medications by 2007.
Despite this growth, the number of individuals receiving pharmacotherapy continues to be small relative to the large number with substance use disorders. With 7.9 million people in the United States dependent on alcohol during the period 2001-2002 (Grant et al., 2004
) and only 705,000 prescriptions filled for alcoholism medications in that year, at most, approximately 9% of the population needing alcoholism treatment received the equivalent of a single prescription of a medication approved to treat the disorder. Moreover, despite a large potential market, the current sales figure for alcoholism medications may not be large enough to engender focused interest and marketing dollars from industry. No addiction medication has become a “blockbuster drug” (i.e., achieving $1 billion in sales in any year). Because pharmaceutical companies have historically based their business model on investment in medications with the potential for a large sales volume, the sales figures for alcoholism and opioid medications may be a deterrent to additional investment in the development and marketing of new alcoholism medications (Cutler, 2007
; Gilbert, 2003; Cuatrecasas, 2006
Prior research has found a variety of obstacles to greater adoption of substance dependence medications including physicians’ perceptions of limited effectiveness, difficulty “seeing” an impact of the medication, poor information dissemination, medication adverse effects, inadequate time available to physicians for patient management, patient reluctance to take medications, and high prices of medication (Mark et al., 2003a, 2003b, 2003c, Thomas et al., 2003). Substance abuse specialty provider characteristics that have been found to be positively associated with adoption of alcoholism medications include accreditation, physician employment by the facility, integrated patient care for co-occurring psychiatric conditions, more revenue from commercial insurance, and fewer linkages with the criminal justice system (Ducharme et al., 2006
). Finally, in addition to these factors, reimbursement issues may be important barriers to the greater adoption of substance dependence medications. Horgan and colleagues (2008)
, using a nationally representative survey, found that 31% of private insurance products excluded buprenorphine from formularies and 55% placed it on the highest cost-sharing tier. We are unaware of research that has examined Medicaid coverage of alcoholism medications or buprenorphine but clearly the extent of Medicaid coverage would influence utilization.
Another factor that is important to consider when parsing out the drivers of adoption is the level of marketing effort exerted by the pharmaceutical company. One hypothesis as to why Campral® (acamprosate) may have diffused more rapidly than ReVia® (naltrexone) is that Forest Laboratories has been more aggressive in disseminating information about acamprosate relative to the marketing effort by DuPont Pharmaceutical Company for naltrexone. In addition, the amount of prescribing by physician specialty may also have important policy implications. Mark and colleagues found that psychiatrists adopted new antipsychotic and alcoholism medications earlier than primary care practitioners (Mark et al, 2002
, Mark et al, 2003
). Consistent with this evidence, our data indicate that psychiatrists appear to have adopted acamprosate earlier than general practitioners. However, we did not find that the same was true for buprenorphine hydrochloride/naloxone prescribing, perhaps because some primary care practitioners may treat addicted patients without specializing in this area. One question for future studies is whether the specialty of the prescriber influences the nature of the treatment received, such as whether patients also receive the ancillary psychosocial services that are indicated when these medications are prescribed, and their degree of adherence with these medications.
The addition of new prescription medications to treat substance dependence offers additional treatment options for patients and may encourage a different patient population to obtain treatment than that traditionally found at substance abuse treatment facilities (Johnson, 2008
; Kreek et al., 2005
; Kreek et al., 2002
; O'Brien, 2005
). Research advances may contribute to the development of new substance dependence medications with enhanced effectiveness and safety profiles (Litten et al., 2005
). The level of adoption by physicians of these new medications and the degree to which the pharmaceutical industry will pursue opportunities in this area, however, remains uncertain.