MONDAY, July 25 (HealthDay News) -- A single heroin vaccine producing specific antibody titers against heroin and its psychoactive metabolites successfully blunt the physiological effect of the drug, according to an experimental study published online June 21 in the Journal of Medicinal Chemistry.
G. Neil Stowe, from the Scripps Research Institute in La Jolla, Calif., and colleagues investigated a singular vaccine strategy against heroin addiction with potential to display multiple drug-like antigens. Two haptens synthesized were heroin-like immunoconjugate-11b and morphine-like immunoconjugate-12b. Antibody titers were monitored to study vaccine immunogenicity in three groups of male Wistar rats vaccinated six times with the heroin- or morphine-like vaccine, or a carrier protein (negative control). Antibody affinity for heroin, 6-acetylmorphine (6AM), and morphine were tested by competition Enzyme-Linked Immunosorbent Assay (ELISA). The vaccine's ability to specifically block heroin effects (mechanical and thermal), and block acquisition of heroin self-administration was tested.
The investigators identified significant antibody production by ELISA. The antibody titer increased with each injection with maximum titer after three injections. No titers were observed in controls. Heroin-like antisera bound 6AM with high affinity, and heroin and morphine with decreased affinity. Morphine-like antisera bound morphine with high, and heroin with decreased affinity but did not bind 6AM. Heroin-like vaccine produced no significant difference from baseline response to either thermal or mechanical sensitivity tests, while morphine-like vaccine showed a significant thermal but no mechanical antinociceptive response to heroin. Only the heroin-like vaccine significantly reduced the likelihood of acquisition of heroin self-administration.
"A vaccine for heroin addiction could prove to be a useful tool for combating heroin addiction, wherein it exploits a motivated recovering addict's own immune system to blunt heroin's psychoactive effects in case of relapse," the authors write.