Buspirone anti-anxiety drug. Computer model of a molecule of buspirone, marketed as Buspar, an anxiolytic (anti-anxiety) drug. Molecules are represented as spheres and are colour-coded: carbon (green), hydrogen (white), oxygen (red) and nitrogen (blue). It is not known exactly how buspirone works, but it is thought to mimic serotonin, a neurotransmitter that has various effects on the brain.