Are laboratory tests required before initiating Invega (paliperidone) therapy?

Laboratory Testing Requirements Before Starting Invega (Paliperidone)

Based on the FDA drug label, laboratory tests are recommended before starting Invega (paliperidone) therapy, particularly for patients with risk factors for diabetes mellitus. 1

Required Baseline Laboratory Tests

• Fasting blood glucose testing is recommended before initiating paliperidone, particularly for patients with risk factors for diabetes mellitus (e.g., obesity, family history of diabetes) 1
• Complete blood count should be obtained to establish baseline hematologic parameters 2
• Liver function tests (ALT, AST, alkaline phosphatase, bilirubin) should be performed to screen for pre-existing liver disease 2
• Renal function tests are important since paliperidone is primarily eliminated through the kidneys as unchanged drug (59%) 3, 4
• Lipid profile (cholesterol, LDL, HDL, triglycerides) should be checked as atypical antipsychotics have been associated with dyslipidemia 1

Rationale for Pre-Treatment Laboratory Testing

• Atypical antipsychotics including paliperidone have been associated with metabolic changes that may increase cardiovascular risk, including hyperglycemia, dyslipidemia, and weight gain 1
• Paliperidone's primary route of elimination is renal (59% excreted unchanged in urine), making baseline renal function assessment particularly important 4
• Unlike its parent drug risperidone, paliperidone has minimal hepatic metabolism through the cytochrome P450 system, which may make it preferable in patients with liver disease 4
• Early detection of metabolic abnormalities allows for appropriate monitoring and intervention during treatment 1

Special Considerations

• For patients with pre-existing diabetes, regular monitoring for worsening of glucose control is recommended 1
• Patients should be monitored for symptoms of hyperglycemia (polydipsia, polyuria, polyphagia, weakness) during treatment 1
• Unlike some other psychiatric medications (e.g., valproate), paliperidone does not require as extensive baseline laboratory testing 5
• The American Academy of Child and Adolescent Psychiatry recommends baseline physical examination to document any pre-existing abnormal movements before starting antipsychotics to avoid later mislabeling them as medication side effects 2

Ongoing Monitoring After Initiation

• Patients should be monitored for metabolic changes, including weight gain, hyperglycemia, and dyslipidemia 1
• Patients who develop symptoms of hyperglycemia during treatment should undergo fasting blood glucose testing 1
• Regular monitoring for extrapyramidal symptoms is recommended, as these occurred in 10-26% of patients in clinical trials, depending on dose 3
• Monitoring for prolactin-related adverse events may be necessary, as these occurred in 4% of patients in long-term trials 3

Common Pitfalls to Avoid

• Failure to obtain baseline laboratory tests may lead to difficulty interpreting subsequent abnormalities 5
• Not recognizing that paliperidone is primarily eliminated renally, making renal function assessment particularly important 4
• Overlooking the need for baseline metabolic parameters, which are important for monitoring treatment-emergent metabolic changes 1
• Neglecting to document pre-existing movement disorders, which could later be misattributed to medication side effects 2