Invega Sustenna (Paliperidone Palmitate) Dosing Pattern
Invega Sustenna requires a unique front-loaded initiation protocol: 234 mg on Day 1 and 156 mg on Day 8, both administered in the deltoid muscle, followed by monthly maintenance doses of 39-234 mg (recommended 117 mg) starting on Day 36, which can be given in either the deltoid or gluteal muscle. 1
Initiation Phase (Days 1-8)
- Day 1: Administer 234 mg intramuscularly in the deltoid muscle as the first loading dose 1
- Day 8: Administer 156 mg intramuscularly in the deltoid muscle as the second loading dose 1
- Both loading doses must be given in the deltoid muscle specifically, not the gluteal muscle, to ensure adequate drug absorption during the critical initiation period 1
Maintenance Phase (Day 36 Onward)
- Begin monthly maintenance dosing on Day 36 (approximately 4 weeks after the second loading dose) 1
- The recommended monthly maintenance dose is 117 mg, though the range is 39-234 mg based on individual efficacy and tolerability 1
- Maintenance injections can be administered in either the deltoid or gluteal muscle, providing flexibility for patient comfort and clinical circumstances 1
- Continue monthly injections indefinitely for maintenance therapy, as long-acting injectable antipsychotics significantly reduce relapse rates compared to placebo (30% vs 65% relapse within 1 year) 2
Dose Adjustments
- Higher maintenance doses (up to 234 mg monthly) may provide additional therapeutic benefit but come with dose-related increases in adverse reactions, particularly extrapyramidal symptoms 3
- Lower doses (39-78 mg monthly) may be appropriate for patients experiencing significant side effects while maintaining adequate symptom control 1
- Dose adjustments should be made based on clinical response assessed over at least 4 weeks, as antipsychotic effects become more apparent after the first 1-2 weeks rather than immediately 2
Critical Monitoring Parameters
- Assess psychotic symptoms using standardized scales (such as PANSS) at baseline and at least monthly during the first 6 months 4
- Monitor for extrapyramidal symptoms, which occur in approximately 25% of patients on higher doses 4
- Check prolactin levels and monitor for prolactin-related symptoms (sexual dysfunction, galactorrhea, menstrual irregularities), as paliperidone significantly elevates prolactin, particularly in women 1
- Monitor weight at each visit, as clinically significant weight gain occurs in approximately 15% of patients 4
- Assess for orthostatic hypotension, especially during the initiation phase 3
Common Pitfalls to Avoid
- Never skip or delay the Day 8 loading dose, as this compromises the pharmacokinetic profile and may lead to inadequate symptom control during the critical early treatment period 1
- Do not administer the initial loading doses in the gluteal muscle, as deltoid administration is required for proper absorption kinetics during initiation 1
- Avoid declaring treatment failure before 4-6 weeks at therapeutic doses with confirmed adherence, as antipsychotic effects develop gradually 2, 5
- Do not abruptly discontinue without a plan for alternative antipsychotic coverage, as approximately 65% of patients relapse within 1 year without maintenance treatment 2
Renal Dosing Adjustments
- Renal excretion is the major route of elimination for paliperidone, requiring dose adjustments in patients with renal impairment 3
- For patients with mild renal impairment (creatinine clearance 50-79 mL/min), initiate with 156 mg on Day 1,117 mg on Day 8, and 78 mg monthly maintenance 3
- For moderate to severe renal impairment (creatinine clearance <50 mL/min), Invega Sustenna is not recommended 3
Advantages Over Oral Formulations
- Once-monthly dosing eliminates daily adherence concerns and reduces relapse rates compared to oral antipsychotics 6
- Provides stable plasma concentrations over the dosing interval without the peaks and troughs seen with oral formulations 4
- May be preferred when medication adherence is a concern or when patients prefer less frequent administration 6