The mechanism of action of risperidone in schizophrenia is unclear. The drug’s therapeutic activity in schizophrenia could be mediated through a combination of dopamine Type 2 (D2) and serotonin Type 2 (5HT2) receptor antagonism. The clinical effect from risperidone results from the combined concentrations of risperidone and its major active metabolite, 9-hydroxyrisperidone (paliperidone). Antagonism at receptors other than D2 and 5HT 2 may explain some of the other effects of risperidone

Risperidone injection is an atypical antipsychotic indicated:

• For the treatment of schizophrenia.
• As monotherapy or as adjunctive therapy to lithium or valproate for the maintenance treatment of Bipolar I Disorder.

For patients who have never taken oral Risperidone, tolerability should be established with oral Risperidone prior to initiating treatment with Risperidone.

Administer by deep intramuscular (IM) deltoid or gluteal injection. Each injection should be administered by a health care professional using the appropriate enclosed safety needle (1-inch for deltoid administration alternating injections between the two arms and 2-inch for gluteal administration alternating injections between the two buttocks). Do not administer intravenously.

25 mg intramuscular (IM) every 2 weeks. Patients not responding to 25 mg may benefit from a higher dose of 37.5 mg or 50 mg. The maximum dose should not exceed 50 mg every 2 weeks.

Oral Risperidone (or another antipsychotic medication) should be given with the first injection of Risperidone, and continued for 3 weeks (and then discontinued) to ensure adequate thera peutic plasma concentrations from Risperidone

Upward dose adjustment of Risperidone should not be made more frequently than every 4 weeks. Clinical effects of each upward dose adjustment should not be anticipated earlier than 3 weeks after injection.

Avoid inadvertent administration into a blood vessel.

Known hypersensitivity to risperidone, paliperidone, or to any excipients in Risperidone

• Increased mortality in elderly patients with dementia-related psychosis
• Cerebrovascular adverse events, including stroke, in elderly patients with dementia-related psychosis
• Neuroleptic malignant syndrome
• Tardive dyskinesia
• Metabolic changes
• Hyperprolactinemia
• Orthostatic hypotension
• Falls
• Leukopenia/Neutropenia and Agranulocytosis
• Potential for cognitive and motor impairment
• Seizures
• Dysphagia
• Priapism
• Thrombotic Thrombocytopenic Purpura (TTP) 
• Disruption of body temperature regulation
• Avoidance of inadvertent injection into a blood vessel

• Increased Mortality in Elderly Patients with Dementia-Related Psychosis
• Cerebrovascular Adverse Events, Including Stroke, in Elderly Patients with Dementia-Related Psychosis
• Neuroleptic Malignant Syndrome
• Tardive Dyskinesia
• Hyperprolactinemia
• Orthostatic Hypotension

Use in Special Populations

Renal or Hepatic Impairment: dose appropriately with oral Risperidone prior to initiating treatment with Risperidone. A lower starting dose of Risperidone of 12.5 mg may be appropriate in some patients.

Pediatric Use: safety and effectiveness not established in patients less than 18 years of age.

Elderly: dosing for otherwise healthy elderly patients is the same as for healthy nonelderly. Elderly may be more predisposed to orthostatic effects than nonelderly.

Pregnancy & Lactation

Pregnancy: Advise patients to notify their healthcare provider if they become pregnant or intend to become pregnant during treatment with Risperidone

Lactation: Advise breastfeeding women using Risperidone to monitor infants for somnolence, failure to thrive, jitteriness, and extrapyramidal symptoms (tremors and abnormal muscle movements) and to seek medical care if they notice these signs