What is Invega (Paliperidone)?
Invega is the brand name for paliperidone, an atypical antipsychotic medication prescribed for the treatment of schizophrenia in adults and adolescents, and schizoaffective disorder in adults [1.8.4, 1.8.5]. It works by altering the effects of certain chemicals in the brain, specifically dopamine and serotonin, to help regulate thoughts, mood, and behavior [1.8.4]. Paliperidone is the major active metabolite of risperidone (Risperdal), meaning they work in very similar ways [1.4.3]. Invega is available in several formulations, including a once-daily extended-release oral tablet (Invega) and long-acting injections administered by a healthcare professional, such as Invega Sustenna (monthly), Invega Trinza (every 3 months), and Invega Hafyera (every 6 months) [1.8.3, 1.8.4].
Why Does Invega Cause Sleepiness?
The sedative effects of Invega are linked to its mechanism of action. While its primary targets are dopamine (D2) and serotonin (5HT2A) receptors, paliperidone also acts as an antagonist at H1 histaminergic receptors [1.4.1, 1.4.2]. The blockade of H1 histamine receptors is a well-known mechanism that causes sedation and drowsiness, which is the same way many over-the-counter sleep aids and allergy medications work [1.4.2, 1.6.2]. This effect can be more pronounced when starting the medication or after a dose increase [1.2.4].
How Common is Sleepiness with Invega?
Sleepiness, also referred to as somnolence or sedation, is one of the most frequently reported side effects of Invega. The prevalence can vary depending on the dosage and the specific formulation (oral vs. injectable).
- Oral Invega (Extended-Release Tablets): In clinical studies, sedation/somnolence was reported in up to 26% of patients taking the oral tablets [1.3.4]. The incidence tends to be dose-related; for example, one pooled analysis showed somnolence reported in 7% of patients on a placebo, compared to 9% on 6 mg, 10% on 9 mg, and 11% on 12 mg of Invega daily [1.7.3].
- Invega Sustenna (1-Month Injection): For the long-acting injection, somnolence/sedation is also a common side effect, though rates in some studies appear slightly lower than the highest oral doses. The manufacturer notes it as one of the most common adverse reactions, occurring in 5% or more of patients and at least twice as often as placebo in clinical trials [1.3.3, 1.3.5]. Some data show rates around 5-7% [1.2.5, 1.3.3].
It's important to know that this drowsiness can impair judgment, thinking, and motor skills, increasing the risk of falls or accidents [1.2.4, 1.9.1].
Comparison of Sedation with Other Antipsychotics
Different atypical antipsychotics have varying levels of sedative effects, largely related to their affinity for the H1 histamine receptor [1.6.2].
| Medication | Active Ingredient | Relative Sedation Level |
|---|---|---|
| Invega | Paliperidone | Moderate [1.3.6] |
| Risperdal | Risperidone | Low to Moderate [1.6.2] |
| Zyprexa | Olanzapine | High [1.6.2, 1.6.3] |
| Seroquel | Quetiapine | High [1.6.3] |
| Abilify | Aripiprazole | Low [1.6.2] |
While Invega is the active metabolite of Risperdal, some studies suggest that risperidone may carry a slightly higher risk of sedation, though findings are not always conclusive [1.6.5]. Olanzapine and quetiapine are generally considered more sedating than paliperidone [1.6.2, 1.6.3].
How to Manage Drowsiness from Invega
If you experience significant drowsiness, it's crucial to speak with your doctor. They can provide personalized advice, but common management strategies include:
- Adjusting Dosing Time: If you are taking the oral tablet once a day, your doctor may suggest taking it in the evening before bedtime to minimize daytime sleepiness [1.5.1, 1.9.2].
- Dose Adjustment: In some cases, your doctor might adjust the dose. The sedative effects can be dose-dependent, so a lower dose may be effective while causing less drowsiness [1.5.4]. Never adjust the dose on your own.
- Allowing Time for Adjustment: For some individuals, the initial drowsiness may lessen or resolve over time as their body gets used to the medication [1.5.4, 1.5.5].
- Avoiding Other Sedating Substances: Alcohol can significantly worsen the drowsiness caused by Invega and should be avoided [1.2.4, 1.2.5]. Be cautious when taking other medications that cause sleepiness, such as benzodiazepines, certain pain relievers, or allergy medicines [1.2.1, 1.9.5].
- Practicing Good Sleep Hygiene: Maintaining a regular sleep schedule, ensuring 7-9 hours of nightly sleep, and avoiding daytime naps can help regulate your energy levels [1.5.5].
- Being Cautious with Activities: Until you know how Invega affects you, avoid driving, operating heavy machinery, or any other activities that require mental alertness [1.5.3, 1.9.1].
Other Common Side Effects
Besides drowsiness, other common side effects associated with Invega include:
- Movement-related (Extrapyramidal) Symptoms: Restlessness (akathisia), stiffness, tremor, and slowed movements [1.2.2, 1.7.3].
- Metabolic Changes: Weight gain, increased blood sugar, and high cholesterol levels are possible, so regular monitoring by a doctor is important [1.5.3, 1.7.4].
- Increased Prolactin Levels: This can lead to missed menstrual periods, breast milk production, or sexual dysfunction [1.7.2, 1.7.4].
- Cardiovascular Effects: Increased heart rate (tachycardia) and orthostatic hypotension (dizziness upon standing) can occur [1.2.4, 1.7.3].
- Injection Site Reactions: For the injectable forms, pain, redness, or swelling at the injection site are common [1.2.3].
Conclusion
Yes, Invega frequently causes sleepiness and drowsiness as a side effect. This is a direct result of its action on histamine receptors in the brain. The effect is common, with up to a quarter of users of the oral tablet reporting it, and it can impact daily functioning and safety. However, this side effect is often manageable. The most important step is to maintain open communication with your healthcare provider. They can help you find the right strategies, whether it's adjusting the timing of your dose, changing the dosage, or simply allowing your body time to adapt, to ensure your treatment is both effective and tolerable.
For more information from the manufacturer, you can visit the official Invega Sustenna® safety page.
