Lonafarnib and Cariprazine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 16, 2026 · Source data updated Jul 16, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lonafarnib
Cariprazine
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
You're taking lonafarnib (Zokinvy) and cariprazine (Vraylar) together. Here's what that means in plain terms. Your body normally breaks down cariprazine using a liver enzyme called CYP3A4. Lonafarnib slows that enzyme down, so cariprazine (and its long-lasting active form) can build up higher than usual, roughly doubling in studies with a similar strong blocker.
More cariprazine in your system can mean stronger side effects, like restlessness, trouble sleeping, drowsiness, or movement changes. The good news is this is very manageable. Your care team can simply use a lower or less frequent cariprazine dose and watch how you're doing. Please don't change anything on your own, just talk with your pharmacist or doctor.
Interaction: Lonafarnib is a strong CYP3A4 inhibitor; cariprazine is a CYP3A4 substrate. Coadministration reduces cariprazine metabolism, increasing exposure to cariprazine and its active metabolite didesmethylcariprazine.
- Direction/magnitude: Increased effect. Ketoconazole increased cariprazine AUC and Cmax by ~100%.
- Evidence: Probable; severity major.
- Management (per labeling): Initiating cariprazine on a strong inhibitor (schizophrenia/bipolar mania): 1.5 mg every 3 days, up to 1.5 mg every other day per response. Bipolar depression/MDD adjunct: 1.5 mg every 3 days. Adding inhibitor to stable therapy: if on 1.5-3 mg daily, reduce to 1.5 mg every 3 days; if on 4.5-6 mg daily, reduce to 1.5 mg every other day. On inhibitor discontinuation, cariprazine dose may need increase.
- Monitor for EPS, akathisia, sedation.
What happens
Increased exposure to cariprazine and its active metabolite, didesmethylcariprazine
Interaction Deep Dive
Giving cariprazine (which is metabolized by CYP3A4) together with a potent CYP3A4 inhibitor can raise the levels of both cariprazine and its active metabolite didesmethylcariprazine. In drug interaction studies, combining cariprazine with ketoconazole (a strong CYP3A4 inhibitor) produced roughly a 100% rise in both AUC and Cmax. For this reason, if cariprazine is being started in a patient already receiving a strong CYP3A4 inhibitor for schizophrenia or bipolar mania, begin with 1.5 mg by mouth every 3 days, then, if warranted by clinical response and tolerability, increase to 1.5 mg orally every other day. For bipolar depression or as adjunctive therapy in MDD, a patient on a strong CYP3A4 inhibitor should take 1.5 mg orally every 3 days. If a strong CYP3A4 inhibitor is introduced in someone already stabilized on cariprazine, dosage changes are required: for patients currently taking 1.5 or 3 mg once daily, adjust cariprazine to 1.5 mg orally every 3 days when the strong inhibitor is started; for patients currently taking 4.5 or 6 mg once daily, adjust cariprazine to 1.5 mg orally every other day when the strong inhibitor is started. Once the strong CYP3A4 inhibitor is stopped, the cariprazine dose may have to be raised according to clinical response and tolerability1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of cariprazine
How to manage this interaction
Keep taking both medicines as prescribed and let your care team handle the adjustment. Because lonafarnib slows the breakdown of cariprazine, your team will typically use a lower and less frequent cariprazine dose to keep levels safe.
- Expect your dose to be reduced (for example, taken every 3 days or every other day) and individualized to how you respond.
- If lonafarnib is later stopped, your cariprazine dose may need to be increased again.
- Report restlessness, tremor, stiffness, unusual movements, or heavy drowsiness.
Ask your pharmacist or prescriber before making any change so they can time the adjustment correctly.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In drug interaction studies, giving cariprazine 0.5 mg/day together with ketoconazole 400 mg/day led to an increase in total cariprazine AUC and Cmax of roughly 100% 1.
Common questions
Can I take Lonafarnib and Cariprazine together?
Lonafarnib blocks CYP3A4 and raises cariprazine levels (roughly doubling exposure), so your care team will lower and space out the cariprazine dose and monitor you for side effects. Keep taking both as prescribed and check with your pharmacist or doctor before changing anything. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lonafarnib and Cariprazine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Lonafarnib and Cariprazine interaction managed?
Keep taking both medicines as prescribed and let your care team handle the adjustment. Because lonafarnib slows the breakdown of cariprazine, your team will typically use a lower and less frequent cariprazine dose to keep levels safe. Expect your dose to be reduced (for example, taken every 3 days or every other day) and individualized to how you respond. If lonafarnib is later stopped, your carip… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Lonafarnib or Cariprazine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: VRAYLAR(R) oral capsules, cariprazine oral capsules. AbbVie Inc. (per FDA), North Chicago, IL, 2024. DailyMed
Keep reading about Lonafarnib
Keep reading about Cariprazine
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