Three of the four case study drugs were for patient populations perceived to be difficult to study for a variety of reasons (e.g., patient recruitment, compliance, and co-morbidities). For example, patient compliance has been seen as a barrier to the success of naltrexone in both the heroin addiction and alcoholism markets, because the drug is not effective unless patients take part in a treatment program with a more intensive psychosocial component than for other pharmacotherapies. Compliance is often an issue when treating patients with schizophrenia, primarily because they may not recognize their illnesses or understand the need for treatment. In addition, alcoholics and other substance abusers may also have severe co-morbidities (e.g., hepatitis or depression), which may lead to poor clinical trial outcomes or adverse events that are unrelated, but wrongly attributed, to the study medication. Finally, researchers involved in the development of LAAM and naltrexone had difficulty recruiting patients because methadone maintenance clinics were unwilling to refer patients to clinical trials for fear of lowering their patient census and associated reimbursement.
Representatives of two companies stressed that cocaine abuse and addiction drugs in the pipeline need better access to patients for conducting clinical trials. A representative of another company described how adverse effects experienced by cocaine patients with multiple co-morbidities could be improperly attributed to its investigative treatments. Although pharmaceutical company representatives viewed these patient-related difficulties as real problems, they did not regard these problems as absolute barriers that could not be overcome given other incentives for entering the market.