Risperidone (Risperdal)


Brandname Risperdal
Class Second-Generation Antipsychotics
Target Antagonism of D2, 5-HT2A, alpha 1, alpha 2, and H1 receptors.
  • Risperidone has a very high 5-HT2A/D2 ratio (which means it has a higher affinity for 5-HT2A receptors than for D2 receptors).

Cytochrome P450 Metabolism

Substrate of 2D6, 3A4
Induces -
Inhibits -

PO Dosing

Starting 2mg PO
Titration 1-2mg PO q24 hours
Maximum 16mg
Taper Slow taper
½ Life 26 hours, metabolite = 3-6 days

Clinical Pearls

  • Risperidone 25mg IM is equivalent to about 2 to 3 mg oral risperidone (approximately)
  • When starting a patient on Risperdal Consta IM, the PO and IM must overlap for 3 weeks before the IM injection takes full effect
  • In severe renal and hepatic impairment, a lower starting dose of 0.5 mg BID should be used. May increase to dosages above 1.5 mg twice daily at intervals of one week or longer
  • Risperidone at higher doses (6-8mg) acts more like a high potency first-generation anti-psychotic. There is a dose-responsive relationship with dose and incidence of EPS.[1]
  • Concomitant administration of risperidone with fluoxetine may increase the plasma concentration of risperidone by 2-3 fold.[2]

Treatment for

First line Notes
Schizophrenia Target dose 4 to 8 mg
Bipolar I Disorder, mania Target dose 1 to 6 mg
Indicated Notes
Autism Spectrum Disorder (ASD) Treatment of irritability (low doses, 0.5-1mg max)