Cariprazine and Letermovir Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Cariprazine
Letermovir Injection
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.
What happens
Increased cariprazine and its major active metabolite (didesmethylcariprazine (DDCAR)) exposure
Interaction Deep Dive
Coadministration of cariprazine (a CYP3A4 substrate) and a moderate CYP3A4 inhibitor may increase the exposure of both cariprazine and its active metabolite, didesmethylcariprazine. When initiating cariprazine treatment while taking a moderate CYP3A4 inhibitor (for schizophrenia or bipolar mania), start at 1.5 mg orally every other day; increase to 1.5 mg orally every other day, if needed and depending upon clinical response and tolerability. When taking a moderate CYP3A4 inhibitor (for bipolar depression or adjunctive therapy for treatment of MDD), take 1.5 mg orally every other day. Initiating a moderate CYP3A4 inhibitor while taking a stable dosage of cariprazine: currently on 1.5 or 3 mg once daily, and when initiating the moderate inhibitor, adjust cariprazine dosage to 1.5 mg orally every other day. Currently on cariprazine 4.5 or 6 mg once daily, and when initiating the moderate inhibitor, adjust cariprazine dosage to 1.5 mg orally once daily. When the moderate CYP3A4 inhibitor is discontinued, the cariprazine dosage may need to be increased based on clinical response and tolerability1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of cariprazine
Literature reports
1 report — tap to read
a) During drug interaction studies, coadministration of cariprazine 1.5 mg/day and erythromycin (moderate CYP3A4 inhibitor) 500 mg twice daily for 21 days, resulted in increased cariprazine AUC (0 to 24 hours) and Cmax by approximately 50% 1. In one study including only White males receiving cariprazine 1.5 mg/day and erythromycin 500 mg twice daily (n=40), AUCs were increased by 38% (cariprazine), 11% (desmethylcariprazine, an active metabolite), and 60% (didesmethylcariprazine, an active metabolite), and Cmax by 34%, 16%, and 62%, respectively. Tmax was not affected by coadministration with erythromycin 2.
Common questions
Can I take Cariprazine and Letermovir Injection together?
Increased cariprazine and its major active metabolite (didesmethylcariprazine (DDCAR)) exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cariprazine and Letermovir Injection 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 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 Cariprazine or Letermovir Injection 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 (2)
- Product Information: VRAYLAR(R) oral capsules, cariprazine oral capsules. AbbVie Inc. (per FDA), North Chicago, IL, 2024. DailyMed
- Szabo M, Hujber Z, Harsanyi J, et al: Coadministration of cariprazine with a moderate CYP3A4 inhibitor in patients with schizophrenia: implications for dose adjustment and safety monitoring. Clin Pharmacokinet 2024; 63(10):1501-1510. PubMed
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