Invega Trinza Paliperidone Palmitate Injection

1. Indications and Usage
Schizophrenia:
Treatment of schizophrenia in adults.
Note: Can be used as initial treatment or maintenance therapy.
2. Dosage and Administration
Route of Administration:
For Intramuscular (IM) Injection ONLY.
Administered by a healthcare professional into the deltoid or gluteal muscle.
Recommended Dosage:
Dosing Frequency: Typically administered every 4 weeks (monthly).
Starting Dose (Induction):
Day 1: 234 mg (Deltoid).
Day 8: 156 mg (Deltoid).
Maintenance:
The dose is individualized based on efficacy and tolerability.
Recommended starting maintenance dose is 117 mg (Gluteal or Deltoid) every 4 weeks.
Dose range: 39 mg to 234 mg every 4 weeks.
Missed Dose:
If the patient misses a dose, the injection should be given as soon as possible and the schedule reset.
3. Mechanism of Action
Receptor Profile:
Paliperidone is the active metabolite of Risperidone (9-hydroxyrisperidone). It is a selective monoaminergic antagonist with high affinity for Serotonin (5-HT2A) and Dopamine (D2) receptors.
Nanocrystal Technology:
Unlike the microsphere technology used in Aripiprazole (Aristada), Paliperidone Palmitate is formulated as nanocrystals suspended in an aqueous vehicle.
Dissolution-Limited Release: Upon IM injection, the drug dissolves slowly into the surrounding tissue fluid due to its low water solubility, forming a “drug depot.”
Hydrolysis: The ester bond is hydrolyzed to release the active drug (paliperidone) into the systemic circulation.
Half-Life: The apparent half-life ranges from 25 to 49 days depending on the injection site.
4. Safety and Warnings
Increased Mortality in Elderly with Dementia (Boxed Warning):
Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death.
Suicidal Thoughts and Behaviors:
Monitor for the emergence of suicidal ideation and behavior.
Injection Site Reactions:
Pain, erythema, and induration at the injection site are common.
QTc Prolongation:
Paliperidone causes a modest increase in the QTc interval. Caution is advised in patients with cardiac history or those taking other QT-prolonging drugs.
Elevated Prolactin:
Paliperidone is associated with hyperprolactinemia, which may lead to galactorrhea, gynecomastia, and menstrual irregularities.
5.Adverse Reactions
Most Common:
Injection site pain, headache, anxiety, insomnia, upper abdominal pain, nausea, vomiting, and diarrhea.
6.Drug Interactions
CYP3A4 Inducers:
Co-administration with strong CYP3A4 inducers (e.g., carbamazepine) may decrease paliperidone plasma levels; dose adjustment may be necessary.
QT-Prolonging Drugs:
Concomitant use with other drugs that prolong the QTc interval is not recommended.
Pimozide:
Contraindicated due to the risk of serious cardiac arrhythmias.
7.Pharmaceutical Information
Chemical Composition:
Active Ingredient: Paliperidone Palmitate.
Appearance: Sterile, white to off-white suspension in a syringe.
Storage: Store at 25°C (77°F); excursions permitted to 15–30°C (59–86°F). Do not freeze.