Are there any interactions between Invega (paliperidone) and marijuana?

Interactions Between Invega (Paliperidone) and Marijuana

Concurrent use of Invega (paliperidone) and marijuana may lead to additive central nervous system effects including dizziness, confusion, somnolence, and fatigue, and requires careful monitoring for adverse effects. 1

Pharmacological Interactions

• THC (tetrahydrocannabinol), the primary psychoactive component in marijuana, inhibits several cytochrome P450 enzymes, particularly CYP3A4, CYP2C9, and CYP2C19, which could theoretically affect the metabolism of medications including paliperidone 1

• Both substances can cause central nervous system depression, potentially leading to additive effects when used together, including increased sedation, dizziness, and cognitive impairment 1

• The variable THC and CBD content in cannabis products makes drug interactions unpredictable and difficult to standardize when combined with medications like paliperidone 1

• Paliperidone, as an atypical antipsychotic, works primarily through antagonism of dopamine D2 and serotonin 5-HT2A receptors, which may interact with cannabis effects on these same neurotransmitter systems 2

Clinical Concerns

• Marijuana use may potentially interfere with the therapeutic effects of paliperidone in treating schizophrenia or schizoaffective disorder 3

• Patients using both substances concurrently should be monitored for:

  • Increased sedation and somnolence 1
  • Cognitive impairment and confusion 1
  • Changes in blood pressure and heart rate 1
  • Worsening of psychiatric symptoms 3

• THC has been associated with psychotic symptoms in some individuals, which could potentially counteract the antipsychotic effects of paliperidone 3

• Cannabis use has been linked to behavioral health issues including anxiety and depression, which may complicate management of patients with psychiatric disorders 3

Special Populations at Higher Risk

• Elderly patients may be at increased risk for adverse effects due to:

  • Reduced drug clearance 1
  • Higher risk for confusion and falls when using cannabis 3
  • Potential for more pronounced sedative effects 3

• Patients with cardiovascular conditions require additional monitoring as both substances can affect heart rate and blood pressure 1

• Patients with a history of psychotic disorders should be particularly cautious with THC use, as it may exacerbate symptoms 3

Recommendations for Management

• If a patient chooses to use cannabis while on paliperidone:

  • Start cannabis products at the lowest possible dose and increase slowly 1
  • Allow sufficient time between dose adjustments to gauge effects 1
  • Monitor for increased side effects when initiating or changing the dose of either substance 1

• Patients should be advised to avoid driving or operating heavy machinery when feeling the effects of cannabis, which typically means waiting 5-8 hours after use 3

• Consider the formulation of cannabis products:

  • Edible forms may have delayed onset (up to 2 hours) but longer duration 3
  • Inhaled forms have more rapid onset but shorter duration 3
  • Avoid high-fat meals when taking oral cannabis products as this increases cannabinoid absorption and may exacerbate drug interactions 1

• Be vigilant about the potential for adulterated cannabis products, which may contain synthetic cannabinoids that could lead to unpredictable interactions 1

Patient Education Points

• Patients should be encouraged to disclose cannabis use to their healthcare providers to ensure appropriate monitoring and dose adjustments 3

• Educate patients about potential additive sedative effects and the importance of avoiding other CNS depressants 1

• Inform patients about the variable potency and composition of cannabis products, which can make interactions unpredictable 3, 1

• Advise patients to store cannabis products safely away from children and pets 3