You will be shown a paragraph from a biomedical research article. Your task is to extract all drug combinations appearing in a specific sentence within in the paragraph. Each drug combination should be assigned to one of the following three categories:

- POS: Indicates a positive interaction between the drugs in the combination; for instance, drugs that have an additive or synergistic effect.
- NEG: Indicates a negative interaction between the drugs in the combination; for instance, combining these drugs might result in adverse side effects, or might reduce their efficacy.
- COMB: Indicates that the drugs are given in combination, but the type of interaction between the drugs cannot be determined based on the provided context.

Please format your answer as a json array. Each entry in the array should itself be an array formatted as [<drug_1>, <drug_2>, ..., <drug_n>, <category>] where <category> is one of the three categories listed above and <drug_1>, ..., <drug_n> are drug names copied verbatim from the input sentence. Different combinations may involve different numbers of drugs; in other words, the `n` in <drug_n> may vary.

As an example, the following output describes two extracted drug combinations; one between two drugs, and one between three drugs:

[["artesunate", "artemether", "COMB"], ["Nifedipine", "Labetalol", "Prazosin", "POS"]]

The paragraph and specific sentence are below. You should only extract relationships expressed in the specific sentence; the paragraph is provided for context.

In your output, return only the json array and no other text. If no drug combinations appear, return an empty array `[]`.

paragraph: Drug interactions between warfarin and lenvatinib in a patient with the CYP2C9*1/*3 and VKORC1-1639G/A genotype. lenvatinib inhibits CYP2C8. (S)-warfarin is metabolized to (S)-7-hydroxywarfarin by CYP2C9 and (S)-4'-hydroxywarfarin by CYP2C8. Here, we report drug interactions between warfarin and lenvatinib in a patient with CYP2C9*1/*3. ### Case Summary The patient was administered warfarin. His international normalized ratio (INR) was 1.92 before lenvatinib administration. On day 8 after beginning 12 mg/day lenvatinib, plasma trough concentrations of lenvatinib and (S)-warfarin were 33.3 ng/mL and 0.67 μg/mL, respectively. On day 10, his INR increased to 3.48. ### What Is New And Conclusion lenvatinib-dependent (S)-warfarin inhibition could involve CYP2C9 and CYP2C8. After initiating warfarin plus lenvatinib , INR assays are necessary .

sentence: After initiating warfarin plus lenvatinib , INR assays are necessary .
[["warfarin", "lenvatinib", "COMB"]]