Invega: Benefits, Side Effects, Dosage, and Interactions

Invega (paliperidone) is a second-generation antipsychotic approved for the treatment of schizophrenia and schizoaffective disorder. However, it may also be prescribed off-label for individuals with bipolar disorder.

Invega is associated with fewer adverse side effects than some of the other antipsychotic drugs. This can help improve compliance with taking the medication, potentially providing better treatment outcomes.

How Invega Works

Invega works by restoring the balance of two neurotransmitters in the brain: serotonin and dopamine. Serotonin helps regulate anxiety and mood, among other actions. Dopamine is important for central nervous system functions such as movement, pleasure, attention, mood, and motivation.

By balancing these neurotransmitters, Invega can help alleviate some of the symptoms of schizophrenia, including:

• Delusions (false beliefs)
• Hallucinations (false sensory experiences)
• Disorganized thinking and speech
• Disorganized and unpredictable behavior

What to Expect

In the first one to two weeks of taking Invega, you may notice improvements in symptoms such as hallucinations and delusions, disorganized thinking, motivation, and desire to be around others. While some of these symptoms may not go completely away, others generally continue to improve the longer you take this medication.

Forms of Invega

There are different forms of Invega that you may be prescribed, each with a different dosage and timing.

Invega Tablets

Invega tablets are taken once a day and the dose of each tablet ranges from 1.5 mg to 9 mg. Typically, patients are prescribed a low dose to start, then it may slowly be increased over several weeks until a therapeutic effect is achieved.

Invega tablets should be swallowed whole—not crushed, broken, or chewed—and taken as directed by your healthcare provider. They can be taken with or without food.

Invega Injections

There are three different Invega injection options that gradually release this medication over time to help control schizophrenia symptoms. They are Invega Sustenna, Invega Trinza, and Invega Hafyera.

Invega Sustenna

Invega Sustenna is an intramuscular injection given every month by a healthcare professional and is usually injected into the upper arm or buttocks. The first two doses are given one week apart, after which Invega in pill form can be discontinued and the patient can switch to a once-monthly medication cycle.

Invega Trinza

Once patients have been adequately treated with Invega Sustenna for at least four months, Invega Trinza may be an option. Invega Trinza injections last three months, meaning that they are only received four times per year.

Invega Hafyera

The longest-lasting of the three, Invega Hafyera injections are given every six months, or twice per year. This medication is an option if you've been on Invega Sustenna for a minimum of four months or Invega Trinza for three months.

Invega Effectiveness

Studies have consistently shown that Invega is both effective and well-tolerated for treating schizophrenia, whether in pill form or as an injection. Invega has also been proven equally effective as a maintenance therapy for schizoaffective disorder, preventing the reappearance of symptoms.

By contrast, studies evaluating the effectiveness of Invega in treating bipolar disorder have been more limited. They've also provided mixed results.

For example, according to a 2018 meta-analysis, Invega performed no better than a placebo in people with bipolar mania and caused far more side effects. Yet, a 2020 study suggests that paliperidone may be effective in reducing both manic and mixed episodes in patients with bipolar I disorder.

Side Effects of Invega

Some people experience side effects when taking Invega, with some of these effects being common and rather mild and others being rare but also more serious.

Common Side Effects

The most common side effects associated with Invega use include:

• Abdominal discomfort or pain
• Constipation
• Extrapyramidal symptoms such as tremors or muscle stiffness
• Drowsiness
• Increased heart rate
• Inflammation of the nose or throat
• Restlessness or agitation
• Weight gain

Additional potential side effects of Invega Sustenna and Invega Trinza include redness, swelling, or pain at the injection site.

Talk to your doctor if you experience side effects which are persistent or severe. Also, don't be afraid to ask questions before you start treatment. Taking this step helps you be better prepared if side effects do arise.

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Rare But Serious Side Effects

Some side effects of Invega can be serious, requiring immediate medical attention. They include:

• Body temperature regulation issues
• Gastrointestinal obstruction
• High blood sugar or cholesterol
• Irregular heartbeat (arrhythmia)
• Low blood pressure and fainting
• Muscle rigidity
• Neuroleptic malignant syndrome
• Painful erection that can last for hours (priapism)
• Seizures, tics, tremors, or convulsions

In rare cases, a person may be allergic to paliperidone and develop a potentially deadly, all-body reaction known as anaphylaxis. Call 911 or go to the nearest emergency room if you develop any of the following:

• Rash or hives
• Shortness of breath and/or wheezing
• Difficulty swallowing (dysphagia)
• Swelling in the face, throat, neck, or extremities

Long-Term Side Effects

Tardive dyskinesia is a side effect that sometimes develops with long-term use of antipsychotics. Symptoms include grimacing, sucking, smacking of lips, and other involuntary movements. While the risk of tardive dyskinesia is low in Invega, it does still exist.

Invega Drug Interactions

Tell your doctor about any or all medication you may be taking, whether they be over-the-counter, prescription, nutritional, herbal, or homeopathic. Some may interact with Invega, including:

• Anti-arrhythmic (irregular heartbeat) drugs
• Anticonvulsant (anti-seizure) drugs
• Antidepressants
• Antihypertensive (high blood pressure) drugs
• Anxiolytic (anti-anxiety) drugs
• Certain antibiotics, such as Avelox (moxifloxacin) or Erythrocin (erythromycin)
• Drugs used to treat Parkinson's disease
• Sedatives and sleeping pills
• St. John's Wort

Invega can make you drowsy, so it's important to be cautious about driving or operating heavy machinery. Alcohol can amplify these effects and should be avoided when taking this medication.

Contraindications of Invega

Invega carries the same black box warning as other atypical antipsychotics regarding the increased risk of death in elderly people with dementia-related psychosis. Invega, either in pill or injectable form, is not approved for use in this population.

Invega is also contraindicated for patients with a known sensitivity to risperidone or Risperdal Consta.

Precautions and Considerations for Invega

Invega may contribute to weight gain and an increase in blood sugar and cholesterol. It is important to have these levels monitored while undergoing Invega treatment.

If you are pregnant, planning to become pregnant, or are breastfeeding, tell your doctor immediately as it is unknown what the risks may be to the unborn child.