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: The Role of Local Bupivacaine Irrigation in Postoperative Pain Control After Augmentation Mammoplasty: A Systematic Review and Meta-Analysis. The objective of this study is to analyze the efficacy of local bupivacaine irrigation after augmentation mammoplasty for the control of postoperative pain. ### methods A systematic review and meta-analysis was conducted including all randomized controlled trials (RCTs) that compared the irrigation of bupivacaine (±ketorolac) versus normal saline or no irrigation for pain control after breast augmentation. The primary outcome was postoperative pain measured by visual analog scale. The study protocol was established a priori according to the recommendations of the Cochrane Collaboration. A bibliographical search was conducted in September 2015 in the following Cochrane Library databases: CENTRAL, MEDLINE, EMBASE, and Scielo. The strategy used for the search was ((augmentation AND ("mammoplasty"[MeSH Terms] OR "mammoplasty")) OR (("breast"[MeSH Terms] OR "breast") AND augmentation)) AND (("pain, postoperative"[MeSH Terms])). ### results Four RCTs with a total of 264 participants were included. Two trials compared bupivacaine alone versus placebo (normal saline or no irrigation) and 3 trials compared bupivacaine plus ketorolac versus placebo. The combined irrigation of bupivacaine and ketorolac showed a clinically significant reduction of pain in the first postoperative hour and on postoperative day 5 . The irrigation with bupivacaine compared with placebo significantly reduced pain assessed on postoperative day 4. ### conclusion The irrigation of bupivacaine with or without ketorolac was associated with a reduction of postoperative pain compared with control groups for the first 5 postoperative days. Due to the few number of trials included, these results should be correlated further clinically.

sentence: The combined irrigation of bupivacaine and ketorolac showed a clinically significant reduction of pain in the first postoperative hour and on postoperative day 5 .
[["bupivacaine", "ketorolac", "POS"]]