CHRNA4 and amyotrophic lateral sclerosis: The top three drugs were: varenicline, a partial agonist for the α4β2 nicotinic acetylcholine receptor (nAChR) used for the treatment of nicotine addiction; piperacillin, a β-lactam antibiotic; and riluzole, an anti-glutamatergic drug used to treat amyotrophic lateral sclerosis (see Table 4 for the complete list of drugs).