Researchers have created a vaccine that appears to block methamphetamine’s high in mice (J. Med. Chem. 2016, DOI: 10.1021/acs.jmedchem.6b00084). Methamphetamine is a small molecule, so to create a vaccine, scientists need to link the molecule to a larger carrier, such as a protein, to draw the immune system’s attention and provoke it into striking. The more antibodies produced and the tighter they bind methamphetamine, the better job they should do at keeping it from reaching the brain where it would cause a high. Kim D. Janda of Scripps Research Institute California and colleagues built 12 compounds consisting of methamphetamine bound to a linker molecule, which they conjugated to two candidate carrier proteins. The researchers tested each of the resulting vaccines by injecting them into mice and measuring antibody levels and antibody affinity for methamphetamine. The best vaccine resulted from tetanus toxoid, a protein modified for safe use in vaccines. When given methamphetamine, a stimulant, mice typically increase their activity level. Vaccinated mice moved around about a third as much in the 90 minutes after getting a 2-mg/kg dose of methamphetamine as those given carrier protein alone.