Weighing implications of a cocaine vaccine

On July 6, 1885, Louis Pasteur, working as a researcher and unlicensed physician in Paris, injected an artificially weakened form of the rabies virus into the arm of Joseph Meister, a 9-year-old boy who had been recently bitten 14 times by a rabid dog. Meister's miraculous recovery three months later won Pasteur lasting recognition for the development of the first human vaccine and ushered in the modern era of microbial medicine.

The same year, a young Sigmund Freud arrived from Vienna to begin his studies on hysteria at the Pitie Salpetri?re Hospital, a brisk 10 minute's walk away from Pasteur's appointment at the Ecole Normale Superieure. While Pasteur spent his days sticking sick patients with rabies, Freud spent his nights injecting himself with the newest import from South America -- cocaine. Extolling the therapeutic value of the drug, he praised its "exhilaration and lasting euphoria, which in no way differs from the normal euphoria of the healthy person."

More than a century later, Pasteur's vaccination techniques have significantly diminished the global incidence of rabies, polio and other viral diseases, while Freud's early popularization and mischaracterization of cocaine have been followed by skyrocketing addiction worldwide. Though today's illicit campos de la coca'na nested deep in South American jungles seem distant from 19th century Parisian laboratoires, ongoing U.S. clinical trials of a "cocaine vaccine" by the British pharmaceutical company Xenova suggest that the divergent legacies of Freud and Pasteur may yet cross paths.

The cocaine vaccine essentially works like any other vaccine, utilizing the body's own immune system to sequester foreign molecules before they cross the blood-brain barrier. Alone, cocaine molecules are too small to be noticed by immune cells and therefore pass undetected to the brain. Researchers have overcome this problem by chemically binding cocaine to a larger protein the immune system can easily identify.

The invoked response produces antibodies that have the ability to bind to either the cocaine-protein complex or unbound cocaine molecules, thus intercepting their travel en route to reward centers in the brain. Individuals "vaccinated" in this manner are less likely to get high upon subsequent cocaine injections.

Proponents of the vaccine believe it will help recovering addicts manage their dependency without worry of relapse, possibly mitigating some of the negative psychological effects associated with withdrawal symptoms. Unlike typical vaccinations, however, the cocaine vaccine does not currently provide lifelong immunity and requires regular two to three month injections to remain effective. Most importantly, the vaccine can be overwhelmed by subjecting the immune system to more cocaine substrate than it can handle.

Though more testing is needed before the Xenova trials yield conclusive results, other potential advantages of a cocaine vaccine are fairly obvious. High-risk individuals could be prospectively identified and administered preventive vaccinations to reduce the likelihood of future addiction. Emergency provision of the cocaine vaccine might also improve survival outcomes for overdose victims. More generally, the vaccine would prove a useful tool for health-care professionals specializing in substance abuse, whose pharmacologic repertoire for handling cocaine addiction (unlike heroin or alcohol dependency) remains substantially limited.

Introduction of a cocaine vaccine also raises serious ethical questions, few of which have been subjected to any serious reflection. As with any medical advancement, some problems fall along the lines of access. Given that most serious addicts also earn low incomes, a prohibitively priced cocaine vaccine, no matter how effective, would exclude its target audience. On the other extreme, vulnerable populations could equally face significant social or legal coercion to get vaccinated regardless of each individual's risk, further marginalizing those who choose not to comply. Parallel use of blood antibody screening in the workplace could result in many false-positive identifications for persons who either never used cocaine (and were vaccinated voluntarily or out of compulsion) or who were recovered/recovering addicts (and still had antibodies floating in their bloodstream).

As recently noted by W. Hall, et al, in The British Journal of Medical Ethics, the safety margin provided by cocaine vaccination might also lead to increased incidence of cocaine use among individuals who would otherwise be deterred by the thought of untreatable addiction -- ironically resulting in more cocaine addicts. Similar incentives might compel occasional users to increase the frequency of their consumption, while other vaccinated addicts -- still seeking a high -- might eventually resort to fatally toxic amounts of cocaine or shift consumption to other drugs. Deeper issues concern the justification of behavior modification, particularly with regards to preventive vaccination of adolescent populations and the possible development of long-lasting or permanent vaccination protocols.

These complex ramifications indicate that prudence and thoughtful deliberation are necessary before a cocaine vaccination is made widely available to the medical community and public at large. Balanced regulation and oversight of this evolving technology are crucial requisites for improving the individual lives and public health of future generations. With the benefit of hindsight and unparalleled scientific knowledge, we should hope the fruits of our efforts will be closer in spirit to Pasteur -- and considerably removed from Freud.

Jason Lott is a first-year student in the School of Medicine from Anniston, Ala. Whole Lotta Love appears on alternate Mondays.

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