Shooting Down Addiction: A New Breed Of Vaccines Aims To Wean Users Off Cocaine
Posted August 4th, 2011
As part of our commitment to our clients and employees in the pharmaceutical, biotech, clinical and healthcare industries, we occasionally like to highlight some of the newest research in those fields. A recent story that caught our eye is a report about a new vaccine being developed to help cocaine users kick their addictions.
The cocaine vaccine, which is currently being tested in clinical trials, consists of molecules of cocaine covalently bonded to a large carrier protein, namely a recombinant cholera toxin B subunit (which is harmless in isolation from the natural molecule’s toxic A subunit). This carrier was chosen because a cholera vaccine made from this subunit has been administered to millions of people without any adverse effects. Also, Americans are rarely exposed to or vaccinated against cholera, so most would likely mount a new and robust immune response to this protein and the attached cocaine molecule.
After intramuscular injection, the vaccine enters the bloodstream and triggers plasma cells to produce antibodies to the cocaine-cholera protein. This creates a slew of antibodies that can latch onto free cocaine molecules in the bloodstream and, because they are too bulky to fit through tight junctions in blood vessels, prevent the drug from leaving the circulatory system and entering tissues and organs.
Most importantly, tiny cocaine molecules bound to big antibodies can no longer cross the blood-brain barrier into the brain, where they would ordinarily block dopamine-transport receptors and cause the buildup of dopamine that users perceive as a high. Cocaine that is kept from reaching the brain is prevented from triggering reward sensations. With continued, regular booster vaccinations, necessary because the antibody titer declines steeply about 3 months after reaching peak levels, the bonds of addiction may be loosened, giving addicts a stab at kicking their habit altogether.
Cocaine dependence currently has no FDA-approved pharmacotherapies. For cocaine addicts seeking help, the standard of care is outpatient behavior-modification treatment, but such programs don’t have a good track record of establishing long-term abstinence. The key to helping cocaine addicts overcome their dependency is finding a way to make short-term abstinence stick. For those suffering from debilitating cocaine addictions, a vaccine may provide hope for weaning themselves off the drug for good.
Though the early results of the cocaine vaccine trials are promising, there are significant roadblocks to its commercialization and widespread use. First, society for the most part views substance abuse as a moral failure rather than a brain disease. If addiction is considered a failure of will power and an act of willful misconduct, it will be difficult for the general public and political representatives to accept that a physiological intervention can lead to a cure.
These perception problems then create economic hurdles. Within the pharmaceutical industry, cocaine addicts are considered poor investments for developing medications of any type, although the size of the potential market for this vaccine is likely more than 3 million customers, according to US Substance Abuse and Mental Health Services Administration statistics.
In addition to these economic and social impediments, there are other challenges that complicate the issue. For example, for the vaccine to trigger an effective antibody response, the patient must get the vaccine shots at specific times — at 2, 4, 8 and 12 weeks after the initial vaccination. Committing to this schedule would require significant behavioral intervention for most addicts.
Even with these and other challenges, the success of recent clinical trials and the simplicity of the vaccine’s manufacture and mechanism of action make producing the therapy on a commercial scale relatively inexpensive. This could make the cocaine vaccine available to a wide range of disadvantaged populations both in the developed world and in developing nations, where addictions have had devastating consequences for national economies and health-care systems.
