Is Paliperidone (paliperidone) 150 mg intramuscularly (IM) monthly a suitable treatment option?

Paliperidone 150 mg IM Monthly Dosing

Yes, paliperidone palmitate 150 mg equivalent (234 mg palmitate salt) IM monthly is an approved and appropriate maintenance dose for schizophrenia, falling within the FDA-approved range of 25-150 mg equivalent (39-234 mg palmitate) administered monthly after proper initiation. 1, 2

Approved Dosing Regimen

Initiation Protocol

• Day 1: 150 mg equivalent paliperidone (234 mg palmitate) administered into the deltoid muscle 1, 2
• Day 8 (±2 days): 100 mg equivalent paliperidone (156 mg palmitate) administered into the deltoid muscle 1, 2
• No oral supplementation required with this initiation regimen 1, 2

Needle Selection for Initiation

• Patients <90 kg: Use 1-inch 23-gauge needle 1, 2
• Patients ≥90 kg: Use 1.5-inch 22-gauge needle 1, 2

Monthly Maintenance Dosing

• Dose range: 25-150 mg equivalent (39-234 mg palmitate) 1, 2
• Recommended standard dose: 75 mg equivalent (117 mg palmitate) 1, 2
• Your proposed 150 mg dose represents the maximum approved maintenance dose 1, 2
• Monthly doses may be administered ±7 days without clinically significant impact on plasma concentrations 1, 2

Injection Site Options for Maintenance

• Deltoid muscle: Weight-adjusted needle (same as initiation) 1, 2
• Gluteal muscle: 1.5-inch 22-gauge needle 1, 2
• Note: Deltoid injection produces approximately 28% higher maximum concentrations compared to gluteal injection 3

Clinical Considerations for 150 mg Maintenance Dose

When to Use Maximum Dose

The 150 mg equivalent dose should be reserved for patients who:

• Demonstrated inadequate response to lower maintenance doses (75-100 mg equivalent) 1, 2
• Previously required higher doses for symptom control 4
• Have documented therapeutic benefit at this dose level 3

Dose-Related Adverse Effects

Higher doses (including 150 mg) are associated with increased rates of:

• Extrapyramidal symptoms (more common at higher doses) 3
• Weight gain (dose-related increase) 3
• Elevated prolactin levels (greater in women than men) 4
• Injection site reactions (4-10% vs 2% placebo, dose-dependent) 3

Special Population Adjustments

Renal Impairment

• Mild impairment (CrCl 50-80 mL/min): Dosage adjustment required - reduce maintenance dose 1, 2
• The 150 mg dose may be excessive in this population 1, 2

Hepatic Impairment

• Mild to moderate: No dose adjustment required 1, 2
• Severe: No data available; use with caution 1

Elderly Patients

• Same dosage as younger adults if renal function is normal 1, 2
• Adjust for age-related decline in creatinine clearance 1, 2

Resumption After Treatment Interruption

If Last Dose Was >6 Weeks Ago

• Re-initiation schedule depends on duration since last injection 1
• For prolonged interruptions (>6 weeks), consider restarting with the full initiation protocol (Day 1 and Day 8 deltoid doses) 1

After 7-Week Interruption with Oral Substitution

• Patients previously stable on 150 mg maintenance can resume the same 150 mg dose without re-initiation 5
• Close monitoring for psychotic symptoms recommended for 2-4 weeks after resuming depot therapy 5
• Document target symptoms, treatment response, and monitor for extrapyramidal symptoms, weight gain, and metabolic changes 5

Switching from Other Antipsychotics

From Oral Antipsychotics

• Initiate paliperidone palmitate the day after discontinuing oral antipsychotic 1, 2
• Use standard initiation protocol (Day 1 and Day 8 deltoid injections) 1, 2

From Other Long-Acting Injectables

• Initiate paliperidone palmitate at the time of the next scheduled injection of the previous LAI 1, 2
• Continue monthly thereafter 1, 2
• This applies to switching from long-acting risperidone 1, 2

Pharmacokinetic Profile Supporting Monthly Dosing

• Peak plasma concentrations: Approximately 13 days post-injection 3
• Terminal half-life: Approximately 23 hours for oral formulation; extended release from depot lasts up to 126 days 6, 3
• Release profile: Starts as early as Day 1, providing therapeutic coverage throughout the monthly interval 3
• Renal excretion: Major route of elimination (unlike risperidone, which relies heavily on hepatic metabolism) 6

Monitoring Requirements

Essential documentation for patients on 150 mg maintenance:

• Target symptoms and treatment response 5
• Extrapyramidal side effects 5
• Weight and metabolic parameters 5
• Prolactin-related symptoms (menstrual irregularities, galactorrhea, sexual dysfunction) 4
• Injection site reactions 3