Rucaparib and Colchicine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Rucaparib
Colchicine
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.
Rucaparib (Rubraca) can cause your colchicine to build up in your body. Rucaparib blocks a transporter called P-gp that normally helps pump colchicine out. When that pump is slowed, colchicine levels can rise, and too much colchicine can be dangerous. Signs of colchicine toxicity include stomach pain, nausea, vomiting, diarrhea, muscle weakness, and feeling very tired.
Because this combination can be serious, it is generally something your care team avoids. The good news is that your pharmacist and doctor can manage this by reviewing your medicines, adjusting doses if needed, and watching you closely. Please talk with them before making any changes on your own.
Mechanism: Colchicine is a P-gp (and CYP3A4) substrate. Rucaparib inhibits P-gp, reducing colchicine efflux and increasing systemic exposure, raising risk of colchicine toxicity. Neither drug is a prodrug; effect direction is increased colchicine effect/toxicity.
- Severity: Contraindicated per labeling for colchicine with P-gp inhibitors.
- Evidence: Theoretical (extrapolated from documented P-gp/CYP3A4 inhibitor toxicities, e.g. clarithromycin).
- Onset: Unspecified.
- Management: Avoid combination, especially with renal or hepatic impairment (fatal cases reported). If coadministration is unavoidable in normal organ function, reduce colchicine daily dose or frequency and monitor closely for toxicity (GI symptoms, myopathy, myelosuppression).
What happens
Increased colchicine exposure and an increased risk of colchicine toxicity
Interaction Deep Dive
As a substrate of both CYP3A4 and P-gp, colchicine has been associated with toxicity when given together with clarithromycin, an agent that inhibits both CYP3A4 and P-gp. Reports of toxicity have likewise arisen when colchicine was combined with a CYP3A4 inhibitor and when it was combined with a P-gp inhibitor3. Because life-threatening and fatal colchicine toxicity has been documented in patients taking colchicine at therapeutic doses alongside P-gp inhibitors, the two should not be used together 1. This combination is similarly contraindicated in individuals with renal or hepatic impairment, given that life-threatening and fatal drug interactions have been reported. For patients whose renal and hepatic function is normal 2, when colchicine must be given with a P-gp inhibitor, modify the colchicine dose by lowering either the daily amount or the dosing frequency, and watch closely for signs of colchicine toxicity 3.
Why it happens (mechanism)
Inhibition of P-gp-mediated colchicine efflux transport
How to manage this interaction
Keep taking both medicines exactly as prescribed until you have spoken with your care team, but raise this combination with them soon since it is one they usually try to avoid.
- Your team may choose an alternative or, if both are truly needed, they may reduce your colchicine daily dose or how often you take it.
- They will likely monitor you more closely for signs of colchicine toxicity.
- This combination is especially risky if you have kidney or liver problems, so make sure your team knows your full history.
Call your pharmacist or prescriber promptly if you notice nausea, vomiting, diarrhea, muscle weakness, or unusual fatigue.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Rucaparib and Colchicine together?
Rucaparib can raise colchicine to toxic levels by blocking P-gp, and this pairing is generally contraindicated; do not stop either drug on your own, but contact your pharmacist or doctor right away to review it. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Rucaparib and Colchicine interaction?
It is rated contraindicated. These should generally not be used together.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Rucaparib and Colchicine interaction managed?
Keep taking both medicines exactly as prescribed until you have spoken with your care team, but raise this combination with them soon since it is one they usually try to avoid. Your team may choose an alternative or, if both are truly needed, they may reduce your colchicine daily dose or how often you take it. They will likely monitor you more closely for signs of colchicine toxicity. This combina… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Rucaparib or Colchicine 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 (3)
- Product Information: LODOCO(R) oral tablets, colchicine oral tablets. AGEPHA Pharma USA, LLC (per FDA), Parsippany, NJ, 2023. DailyMed
- Product Information: COLCRYS oral tablets, colchicine oral tablets. Takeda Pharmaceuticals America Inc (per FDA), Deerfield, IL, 2020. DailyMed
- Product Information: GLOPERBA(R) oral solution, colchicine oral solution. Romeg Therapeutics LLC (per FDA), Woburn, MA, 2019. DailyMed
Keep reading about Rucaparib
Keep reading about Colchicine
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