What is the recommended dosing conversion from Invega Sustenna (paliperidone palmitate) to Invega Trinza (paliperidone palmitate)?

Converting from Invega Sustenna to Invega Trinza

Patients who have been adequately treated with Invega Sustenna (paliperidone palmitate monthly) for at least 4 months can be transitioned to Invega Trinza (paliperidone palmitate 3-month) by administering Trinza 3.5 times the last monthly Sustenna dose, given 3 months after the final Sustenna injection. 1

Conversion Dosing Algorithm

The conversion follows a straightforward multiplier approach based on the established monthly maintenance dose:

• If on Sustenna 78 mg monthly → Convert to Trinza 273 mg every 3 months 1
• If on Sustenna 117 mg monthly → Convert to Trinza 410 mg every 3 months 1
• If on Sustenna 156 mg monthly → Convert to Trinza 546 mg every 3 months 1
• If on Sustenna 234 mg monthly → Convert to Trinza 819 mg every 3 months 1

Critical Prerequisites for Conversion

Patients must have received Sustenna for a minimum of 4 months before transitioning to Trinza. 1 This stabilization period is essential because:

• The biphasic pharmacokinetic profile of paliperidone palmitate requires adequate time to establish steady-state concentrations 1
• Premature conversion increases risk of subtherapeutic plasma levels and potential relapse 1
• The complex release characteristics (initial zero-order input followed by first-order maintenance) necessitate documented clinical stability 1

Timing of First Trinza Injection

Administer the first Trinza dose exactly 3 months (not 1 month) after the last Sustenna injection. 1 This timing is critical because:

• Trinza is designed to maintain therapeutic concentrations over a 3-month interval 1
• Earlier administration risks supratherapeutic levels with associated adverse effects including tachycardia, hypotension, QT prolongation, and extrapyramidal symptoms 1
• Delayed administration risks return to subtherapeutic concentrations and increased relapse risk 1

Injection Site Considerations

Maintain consistency in injection site (deltoid versus gluteal) when converting from Sustenna to Trinza. 2 The pharmacokinetic parameters differ significantly between injection sites:

• Deltoid and gluteal injections are not bioequivalent or therapeutically equivalent 2
• Switching between sites may result in unforeseen shifts in elimination half-life, peak plasma concentration, and absorption rate 2
• Using the same maintenance dosing regimen at different sites or alternating between sites can compromise patient outcomes 2

Common Pitfalls to Avoid

Do not administer Trinza at the 1-month mark (when the next Sustenna dose would have been due), as this represents a critical dosing error that could lead to toxicity 1

Do not convert patients who have been on Sustenna for less than 4 months, as inadequate stabilization increases relapse risk 1

Do not assume the conversion ratio is simply 3:1 (three monthly doses combined); the actual ratio is 3.5:1 to account for the different pharmacokinetic profile of the 3-month formulation 1

Do not switch injection sites during or after conversion without recognizing this constitutes a change in bioavailability that may require dose adjustment 2

Clinical Monitoring After Conversion

Monitor for signs of inadequate dosing (emerging psychotic symptoms, agitation, relapse indicators) particularly in the third month of the Trinza dosing interval, as this is when plasma concentrations reach their nadir before the next injection 1

Conversely, monitor for adverse effects in the first month after Trinza administration, as transient excursions above therapeutic concentrations can occur 1