PF-06767832 is a high quality M1 selective PAM (M1 PAM EC50 = 60 nM; M2-M5 PAM EC50 > 10 microM; CNS MPO = 4.9). PF-06767832 has well aligned physicochemical properties, good brain penetration and pharmacokinetic properties. Extensive safety profiling suggested that despite being devoid of mAChR M2/M3 subtype activity, compound 38 still carries gastrointestinal and cardiovascular side effects. These data provide strong evidence that M1 activation contributes to the cholinergic liabilities that were previously attributed to activation of the M2 and M3 receptors.