Camptocormia Secondary to Antipsychotic-Associated Dystonia of the Rectus Abdominis Muscles Detected by Abdominal Computed Tomography

Abstract

However, dopamine supersensitivity can be permanent as seen in tardive dyskinesia. Antipsychotic dose and D2 receptor occupancy follow a hyperbolic association. A similar hyperbolic relationship is seen with antipsychotic dose and therapeutic effects. 12,13 Applying this to perphenazine helps us understand that a maximum response can be expected at lower doses and less robust response at higher doses since most of the D2 receptors are already occupied. Similarly, in reverse, maximal chances of withdrawal are at lower dose ranges. This goes against the conventional linear tapering and demands a hyperbolic taper to prevent a large decrease in receptor occupancy at lower doses. 14 This would prevent a large reduction in D2 occupancy and thereby decrease the risk of withdrawal and relapse. Although this is a lesser-known side effect and a rare clinical occurrence, nevertheless it is an important point that clinicians should be aware of when prescribing antipsychotics with robust D2 antagonist action, especially when working with pediatric population.