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: Vasopressor use and effect on blood pressure after severe adult traumatic brain injury. We describe institutional vasopressor usage, and examine the effect of vasopressors on hemodynamics: heart rate (HR), mean arterial blood pressure (MAP), intracranial pressure (ICP), cerebral perfusion pressure (CPP), brain tissue oxygenation (PbtO(2)), and jugular venous oximetry (SjVO(2)) in adults with severe traumatic brain injury (TBI). ### methods We performed a retrospective analysis of 114 severely head injured patients who were admitted to the neurocritical care unit of Level 1 trauma center and who received vasopressors ( phenylephrine , norepinephrine , dopamine , vasopressin or epinephrine ) to increase blood pressure ### results phenylephrine was the most commonly used vasopressor (43%), followed by norepinephrine (30%), dopamine (22%), and vasopressin (5%). Adjusted for age, gender, injury severity score, vasopressor dose, baseline blood pressure, fluid administration, propofol sedation, and hypertonic saline infusion, phenylephrine use was associated with 8 mmHg higher mean arterial pressure (MAP) than dopamine (P = 0.03), and 12 mmHg higher cerebral perfusion pressure (CPP) than norepinephrine (P = 0.02) during the 3 h after vasopressor start. There was no difference in ICP between the drug groups, either at baseline or after vasopressor treatment. ### conclusions Most severe TBI patients received phenylephrine. Patients who received phenylephrine had higher MAP and CPP than patients who received dopamine and norepinephrine, respectively.

sentence: We performed a retrospective analysis of 114 severely head injured patients who were admitted to the neurocritical care unit of Level 1 trauma center and who received vasopressors ( phenylephrine , norepinephrine , dopamine , vasopressin or epinephrine ) to increase blood pressure
[]