Invega Sustenna (Paliperidone Palmitate) Initiation Protocol
Initiate Invega Sustenna with 150 mg eq (234 mg) on day 1 followed by 100 mg eq (156 mg) on day 8, both administered into the deltoid muscle, with no oral supplementation required. 1, 2
Loading Dose Regimen
Day 1 and Day 8 Deltoid Injections:
- Day 1: Administer 150 mg eq paliperidone (234 mg paliperidone palmitate) into the deltoid muscle 1, 3
- Day 8 (±2 days): Administer 100 mg eq paliperidone (156 mg paliperidone palmitate) into the deltoid muscle 1
- No oral antipsychotic supplementation is necessary with this loading regimen, as therapeutic blood levels are achieved rapidly 2, 3
Needle Selection Based on Weight:
- Patients weighing <90 kg: Use 1-inch 23-gauge needle 1
- Patients weighing ≥90 kg: Use 1.5-inch 22-gauge needle 1
Maintenance Dosing (Starting Day 36)
Monthly Maintenance Injections:
- Recommended dose: 75 mg eq paliperidone (117 mg paliperidone palmitate) monthly 1
- Dosing range: 25-150 mg eq paliperidone (39-234 mg paliperidone palmitate) 1, 3
- Can be administered into either deltoid or gluteal muscle 1, 2
- Monthly doses may be given ±7 days without clinically significant impact on plasma concentrations 1
Needle Selection for Maintenance:
- Deltoid: Weight-adjusted needle size (same as loading doses) 1
- Gluteal: 1.5-inch 22-gauge needle for all patients 1
Switching from Oral Risperidone
Immediate Switch Protocol:
- Initiate paliperidone palmitate the day after discontinuing oral risperidone 1
- For patients on risperidone ≥4 mg/day: Consider bridging with oral risperidone for ≥7 days after the first paliperidone injection, as this is associated with significant reductions in hospitalization days 4
- The package insert does not recommend bridging, but clinical evidence suggests benefit in higher-dose patients to prevent inadequate serum concentrations 4
Switching from Other Long-Acting Injectables
- Initiate paliperidone palmitate at the time of the next scheduled injection of the previous LAI 1
- Continue monthly thereafter with standard maintenance dosing 1
Special Population Dosing Adjustments
Renal Impairment:
- Mild renal impairment (CrCl 50-80 mL/min): Dosage adjustment required 1
- Moderate to severe renal impairment: Further dose reduction necessary 1
Hepatic Impairment:
- Mild or moderate hepatic impairment: No dose adjustment required 1
- Severe hepatic impairment: No data available 1
Elderly Patients:
- Normal renal function: Same dosage as younger adults 1
- Age-related decline in CrCl: Adjust dosage accordingly 1
Managing Missed Doses
Re-initiation Schedule Based on Time Since Last Injection:
- Last dose >6 weeks ago: Re-initiation schedule depends on duration since last injection 1
- The specific re-initiation protocol should follow the same loading dose principles if therapeutic levels have declined 1
Key Advantages Over Other LAIs
- Prefilled syringes in multiple dosage strengths 3
- No refrigeration required 2, 3
- No reconstitution needed prior to administration 2
- Small bore needle with small injection volume 3
- Monthly administration schedule 2, 3
- Biphasic pharmacokinetic profile: initial rapid zero-order input achieves therapeutic concentrations quickly, followed by sustained first-order input for monthly dosing 5
Common Pitfalls to Avoid
Do not skip the deltoid loading doses: The day 1 and day 8 deltoid injections are essential for rapid attainment of therapeutic concentrations; deltoid injection provides approximately 28% higher maximum concentration compared to gluteal injection 1, 3
Do not underdose patients switching from higher-dose oral risperidone: Patients on risperidone ≥4 mg/day may require bridging to prevent relapse risk from inadequate serum concentrations 4
Monitor for injection site reactions: These occur at rates of 4-10% depending on dose regimen, compared to 2% for placebo 3
Be aware of dose-dependent adverse effects: Higher doses (156 mg and 234 mg) show greater efficacy but may have increased rates of extrapyramidal symptoms and weight gain 3