What to monitor before prescribing risperidone (Risperdal) intramuscularly (IM)?

Pre-Prescribing Assessment for Risperidone IM

Before prescribing risperidone intramuscularly, you must obtain a baseline ECG to assess QTc interval, check complete blood count (CBC) if the patient has pre-existing low white blood cell count or history of drug-induced leukopenia/neutropenia, measure baseline metabolic parameters including fasting glucose and lipid panel, assess blood pressure for orthostatic hypotension risk, and screen for cardiac contraindications. 1

Cardiac Evaluation

ECG and QTc Assessment:

• Obtain a baseline ECG before initiating risperidone IM, as antipsychotics can prolong the QTc interval 2
• Rule out recent acute myocardial infarction, which is a contraindication 3
• Identify patients at risk for torsades de pointes or those with baseline QT prolongation 3
• Review all current medications for other QT-prolonging agents 3

Blood Pressure Monitoring:

• Assess baseline blood pressure and screen for orthostatic hypotension risk, particularly important at treatment initiation 1
• Educate patients about orthostatic hypotension and syncope risk 1

Hematologic Screening

Complete Blood Count:

• Check CBC in patients with pre-existing low WBC or history of drug-induced leukopenia/neutropenia 1
• Plan for ongoing CBC monitoring during treatment in these high-risk patients 1

Metabolic Baseline Assessment

Laboratory Testing:

• Obtain fasting blood glucose to establish baseline glycemic status, as risperidone carries risk of hyperglycemia and metabolic changes 1
• Measure baseline lipid panel (cholesterol and triglycerides) 1
• Document baseline weight, as weight gain is a common adverse effect requiring monitoring 4

Patient Education:

• Educate patients about recognizing symptoms of hyperglycemia and diabetes mellitus 1
• Discuss the need for ongoing metabolic monitoring throughout treatment 1

Neurological and Movement Disorder Assessment

Extrapyramidal Symptoms:

• Document baseline movement status, as risperidone can cause extrapyramidal symptoms, particularly at doses above 2 mg/day 5
• Screen for pre-existing Parkinson's disease or dementia with Lewy bodies, which increases risk of extrapyramidal side effects 2
• Assess for any history of tardive dyskinesia 1

Baseline Movement Examination:

• Perform baseline assessment for abnormal involuntary movements to allow comparison during treatment 2
• Document any pre-existing extrapyramidal symptoms 2

Endocrine Screening

Prolactin-Related Assessment:

• Screen for signs and symptoms of hyperprolactinemia including amenorrhea, galactorrhea in females, and erectile dysfunction or gynecomastia in males 1
• Counsel patients that chronic risperidone use may cause hyperprolactinemia 1

Renal Function

Creatinine Clearance:

• Assess renal function, as dose adjustments may be needed in patients with severe renal impairment 2

Special Population Considerations

Pregnancy and Fertility:

• Screen for pregnancy status in females of reproductive potential 1
• Counsel that risperidone may cause extrapyramidal and/or withdrawal symptoms in neonates if used during pregnancy 1
• Advise that risperidone may impair fertility due to increased prolactin levels, though effects are reversible 1

Elderly Patients:

• Use particular caution in elderly patients, starting with lower doses (0.25 mg/day for oral formulations) 2
• Assess for increased risk of orthostatic hypotension and falls 2

Contraindications to Rule Out

Absolute Contraindications:

• Recent acute myocardial infarction 3
• Hypersensitivity to risperidone or any component 1

Relative Contraindications Requiring Caution:

• Baseline QT prolongation or risk factors for torsades de pointes 3
• Concurrent use of other QT-prolonging medications 3
• Severe renal or hepatic impairment 2
• Pre-existing leukopenia or neutropenia 1
• History of priapism 1

Medication Review

Drug Interactions:

• Review all current medications for potential interactions, particularly other QT-prolonging agents 3, 1
• Assess for concurrent use of medications affecting cytochrome P450 2D6 and 3A4 2
• Advise patients to avoid alcohol during treatment 1

Clinical Pitfalls to Avoid

• Do not skip cardiac evaluation: Missing QTc prolongation can lead to life-threatening arrhythmias 3
• Do not overlook metabolic screening: Baseline values are essential for monitoring treatment-emergent metabolic changes 1
• Do not ignore movement disorder history: Patients with Parkinson's disease or Lewy body dementia should not receive risperidone due to high risk of extrapyramidal symptoms 2
• Do not forget CBC in high-risk patients: Those with pre-existing hematologic abnormalities require baseline and ongoing monitoring 1