Synthesis and biological activity of cocaine analogs I: N-alkylated norcocaine derivatives

Probing active cocaine vaccination performance through catalytic and noncatalytic hapten design

Presently, there are no FDA-approved medications to treat cocaine addiction. Active vaccination has emerged as one approach to intervene through the rapid sequestering of the circulating drug, thus terminating both psychoactive effects and drug toxicity. Herein, we report our efforts examining two complementary, but mechanistically distinct active vaccines, i.e., noncatalytic and catalytic, for cocaine treatment. A cocaine-like hapten GNE and a cocaine transition-state analogue GNT were used to generate the active vaccines, respectively. GNE-KLH (keyhole limpet hemocyannin) was found to elicit persistent high-titer, cocaine-specific antibodies and blunt cocaine-induced locomotor behaviors. Catalytic antibodies induced by GNT-KLH were also shown to produce potent titers and suppress locomotor response in mice; however, upon repeated cocaine challenges, the vaccine's protecting effects waned. In depth kinetic analysis suggested that loss of catalytic activity was due to antibody modification by cocaine. The work provides new insights for the development of active vaccines for the treatment of cocaine abuse.

Modulating cocaine vaccine potency through hapten fluorination

Cocaine addiction is a long-lasting relapsing illness characterized by cycles of abuse, abstinence, and reinstatement, and antibody-based therapies could be a powerful therapeutic approach. Herein, we explored the possibility of using halogenated cocaine haptens to enhance the immunological properties of anti-cocaine vaccines. Three fluorine-containing cocaine haptens (GNF, GNCF and GN5F) and one chlorine-containing cocaine hapten (GNCl) were designed and synthesized, based upon the chemical scaffold of the only hapten that has reached clinical trials, succinyl norcocaine (SNC). Hapten GNF was found to retain potent cocaine affinity, and also elicit antibodies in a higher concentration than the parent structure SNC. Our data suggests that not only could strategic hapten fluorination be useful for improving upon the current cocaine vaccine undergoing clinical trials, but it may also be a valuable new approach, with application to any of the vaccines being developed for the treatment of drugs of abuse.

Attenuation of the effects of cocaine on milk consumption in rats by dopamine antagonists

Recent research suggest the both D1 and D2 dopamine (DA) receptors play an important role in the behavioral effects of psychomotor stimulants. The present study utilized selective DA antagonists to examine the role of DA receptors in the effects of cocaine on milk intake in rats. Male Sprague-Dawley rats were given access to a milk solution (2:1 tap water:Bordens sweetened condensed milk) for 15 min each day. When milk intake was stable, dose-response functions were determined for cocaine (4.0-32 mg/kg, IP, 10 min presession) administered alone or in combination with the D1 antagonist SCH 23390 (0.12-0.5 mg/kg, IP, 30 min presession) or the D2 antagonist raclopride (0.25-1.0 mg/kg, IP, 30 min presession). As a control for the serotonin (5-HT2) antagonist effects of SCH 23390, the 5-HT2 antagonist ketanserin (4.0-16 mg/kg) was evaluated as well. To control for nonspecific drug effects on fluid consumption, the effects of cocaine alone on water intake were determined in a separate group of rats. All drugs decreased milk intake when given alone. Both SCH 23390 and raclopride attenuated the effects of at least one dose of cocaine. Ketanserin did not alter the effects of cocaine. These results suggest that stimulation of both D1 and D2, but not 5-HT2, receptors is involved in the effects of cocaine on milk intake in rats.