Invega (Paliperidone)

Invega belongs to the atypical antipsychotic class and is used to manage psychotic disorders.

• Schizophrenia: reduces psychotic symptoms and lowers the risk of relapse.
• Schizoaffective disorder: stabilises mood swings and psychotic features.
• Maintenance treatment of schizophrenia: helps prevent recurrence of symptoms over the long term.

• Paliperidone acts primarily as an antagonist at dopamine D2 and serotonin 5‑HT2A receptors, which modulates neurotransmission implicated in psychosis. It also blocks alpha‑1 adrenergic and histamine H1 receptors, contributing to its therapeutic and side‑effect profile.

Paliperidone may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Weight gain: increase in body mass index observed in many patients.
• Sedation: feeling of drowsiness or reduced alertness.
• Akathisia: inner restlessness and urge to move.
• Constipation: reduced bowel motility leading to difficulty passing stool.
• Dry mouth: decreased salivation causing oral discomfort.
• Dizziness: sensation of light‑headedness, especially when standing quickly.

Serious or Rare Side Effects

• Neuroleptic malignant syndrome: rare but life‑threatening reaction with fever and muscle rigidity.
• Tardive dyskinesia: persistent involuntary movements, often of the face or tongue.
• Orthostatic hypotension: significant drop in blood pressure upon standing, causing faintness.
• Seizures: occasional convulsive episodes, particularly in predisposed individuals.
• Hyperglycaemia: elevated blood glucose levels that may worsen diabetes.
• Elevated prolactin: can lead to galactorrhoea, menstrual disturbances, or sexual dysfunction.

Before initiating therapy with Invega, clinicians should consider several safety measures.

• Metabolic monitoring: regularly assess weight, glucose, and lipid levels.
• Cardiovascular assessment: evaluate blood pressure and heart rate, especially in patients with a history of hypotension.
• Movement disorder surveillance: watch for signs of tardive dyskinesia or akathisia.
• Hepatic and renal function: adjust use if significant impairment is present.
• Elderly caution: avoid use in patients with dementia‑related psychosis due to increased mortality risk.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Paliperidone can interact with other medicines, influencing its effectiveness or safety.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may raise paliperidone levels.
• Strong CYP3A4 inducers (e.g., rifampicin, carbamazepine): may reduce therapeutic exposure.
• Medications that prolong QT interval: increase risk of cardiac arrhythmias.

Moderate Interactions (Monitor Closely):\n- Antihypertensive agents: additive blood‑pressure‑lowering effect.

• Anticholinergic drugs: may exacerbate dry mouth and constipation.
• Antidiabetic medications: monitor glucose as paliperidone can affect glycaemic control.
• NSAIDs and other analgesics: heightened risk of gastrointestinal bleeding.