Phenprocoumon

For an informed discussion with your doctor or pharmacist. This information collection is not a clinically validated interaction checker. Missing data do not establish safety. Do not change or stop prescribed medicines on the basis of this information. The findings apply to the specific conditions studied; laboratory and animal studies cannot be directly extrapolated to humans.

Active substance: Phenprocoumon

Examples of brand names: Marcumar [DE]

ATC code: B01AA04

Main use (for orientation): Anticoagulation

Documented research summary

CBD and Δ9-THC were investigated directly with phenprocoumon in the laboratory. The findings show inhibition of metabolism, but not its magnitude in patients. Phenprocoumon is a distinct drug, not a warfarin metabolite.

Uncertainties and limitations

In-vitro finding specific to the formulation; CBG-rich extract is not isolated CBG. The long half-life limits short-term extrapolation.

Research is limited to the specified date and protocol; it is not globally exhaustive. Brand names and authorisations do not constitute a complete current market overview.

Structured assessment

Category: Direct pair finding

Cannabinoid scope: 28 register names in the documented search family; neither 28 individual clinical trials nor a blanket assessment of all cannabinoids.

Evidence status: Pair-specific evidence, distinguished in the individual findings

Mechanism / drug context: Inhibition of hydroxylation in human liver microsomes; no clinically measured INR effect.

Type of supporting material: See the separate original findings

Clinical interpretation: Requires individual assessment by a doctor or pharmacist. Lack of evidence does not establish safety; no dosage or discontinuation advice is provided.

Context: Phenprocoumon, an active vitamin K antagonist; not an activation-dependent prodrug.

Drug context and gaps in search results are not measured interactions. The source role below describes which statement the source actually supports.

Source role [CA_L_D0002]: Drug context

Statement supported: Supports dosage form, metabolism and/or known risks; alone, it does not substantiate a cannabinoid–drug pair finding.

Source: Marcumar 3 mg Tabletten – Fachinformation [CA_L_D0002]

Source role [CA_P_36814687]: Pair finding

Statement supported: Drug breakdown inhibited in the laboratory.

Source: Phytochemical Comparison of Medicinal Cannabis Extracts and Study of Their CYP-Mediated Interactions with Coumarinic Oral Anticoagulants. [CA_P_36814687]

Scope of review: Individual research with documented title/abstract screening and targeted review of original sections. This is not exhaustive evidence that interactions are absent.

Unresolved source question: The complete stored individual review, label review, literature screening, conclusion and uncertainties were read. Targeted sections of original information were rechecked; no claim is made that all product information or full texts were completely revalidated.

Separately recorded findings

2 separately recorded findings. Each statement applies to its documented study context.

CBD – laboratory and animal studies

Finding ID: V6_D0002_1

Type of result: Finding within the documented study context

Observation: Drug breakdown inhibited in the laboratory.

Mechanism: Inhibition of hydroxylation in human liver microsomes

Study type: In vitro experiment

Context studied: Treyer et al. 2023; pure substances and defined extracts.

Clinical interpretation: Magnitude in humans unknown.

Limitations and uncertainties: No INR/bleeding prediction. A CBG-rich extract tested with general probes is not a direct CBG-pair result.

Original sources for this finding: Phytochemical Comparison of Medicinal Cannabis Extracts and Study of Their CYP-Mediated Interactions with Coumarinic Oral Anticoagulants. [CA_P_36814687]

Δ9-THC – laboratory and animal studies

Finding ID: V6_D0002_2

Type of result: Finding within the documented study context

Observation: Drug breakdown inhibited in the laboratory.

Mechanism: Inhibition of hydroxylation in human liver microsomes

Study type: In vitro experiment

Context studied: Treyer et al. 2023; pure substances and defined extracts.

Clinical interpretation: Magnitude in humans unknown.

Limitations and uncertainties: No INR/bleeding prediction. A CBG-rich extract tested with general probes is not a direct CBG-pair result.

Original sources for this finding: Phytochemical Comparison of Medicinal Cannabis Extracts and Study of Their CYP-Mediated Interactions with Coumarinic Oral Anticoagulants. [CA_P_36814687]

References and access status

[CA_L_D0002] Marcumar 3 mg Tabletten – Fachinformation

Original source / bibliographic reference

Authors: Viatris Healthcare GmbH

Year: 2025

Source type: Approved prescribing information

Source access – 23 October 2026: Source destination was accessible when checked.

Bibliographic attribution or source identity cross-checked.

[CA_P_36814687] Phytochemical Comparison of Medicinal Cannabis Extracts and Study of Their CYP-Mediated Interactions with Coumarinic Oral Anticoagulants.

Original source / bibliographic reference

Authors: Treyer A, Reinhardt JK, Eigenmann DE, Oufir M, Hamburger M.

Year: 2023

Source type: research-article; Journal Article

DOI: 10.1159/000528465

PMID: 36814687

Source access – 23 October 2026: Direct retrieval could not be fully verified; availability remains unresolved.

Bibliographic attribution or source identity cross-checked.

DOI – publisher access (access restrictions may apply)

PubMed Central – full-text access according to the literature database – Archive attribution confirmed by Europe PMC metadata. Direct retrieval was not fully verified here; access may require a browser check.

Europe PMC – full-text access according to the literature database – Listed as freely available HTML full text in the official Europe PMC metadata. Direct retrieval was not fully verified here.

Research as of 23 October 2026. Not all original full texts could be reviewed in full. Source accessibility and the strength of scientific evidence must be assessed separately. An accessible link does not establish medical approval; a bibliographic record with an abstract does not replace the original full text.

Drug search and explanation of the evidence · Guide: cannabinoids and medicines · Author and responsibility