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: Serotonergic mechanism underlying tranylcypromine enhancement of nicotine self-administration. Although nicotine is generally considered to be the main psychoactive component of tobacco, growing evidence highlights the importance of nonnicotine compounds in smoking reinforcement. Monoamine oxidase (MAO) inhibition is a major consequence of smoking and MAO inhibitors, such as tranylcypromine, increase nicotine reinforcement. tranylcypromine has multiple pharmacological effects, increasing monoamine release for a few hours immediately after its administration and blocking MAO activity for several days. To assess the relative role of these two actions, adult male rats were tested in consecutive daily 3-h sessions for self-administration of nicotine (3 μg kg⁻¹) inj⁻¹, i.v.) either 20 or 1 h following administration of tranylcypromine (3 mg kg⁻¹). Both paradigms were shown to produce highly significant inhibition of MAO activity. However, whereas animals readily acquired self-administration when pretreated with tranylcypromine 1 h prior to testing, they did not with the longer pretreatment interval. Such animals did immediately acquire nicotine self-administration when the tranylcypromine pretreatment interval was switched to 1 h prior to testing on Day 4, indicating that an acute effect of the MAO inhibitor was responsible for enhanced nicotine reinforcement. Several lines of evidence implicate serotonin ( 5-HT ) as the mediator of this enhancement : ( 1 ) Tranyclypromine-enhanced nicotine reinforcement was blocked by the 5-HT₂ receptor antagonists , ritanserin and ketanserin ; ( 2 ) parachloroamphetamine ( PCA ) , a 5-HT releaser , also enhanced nicotine self-administration in animals in which MAO activity was inhibited ; ( 3 ) pretreatment with tranylcypromine increased PCA-induced 5-HT overflow in the nucleus accumbens . These findings suggest that MAO inhibition enhances serotonergic transmission, which serves a critical role in the reinforcing effects of nicotine.

sentence: Several lines of evidence implicate serotonin ( 5-HT ) as the mediator of this enhancement : ( 1 ) Tranyclypromine-enhanced nicotine reinforcement was blocked by the 5-HT₂ receptor antagonists , ritanserin and ketanserin ; ( 2 ) parachloroamphetamine ( PCA ) , a 5-HT releaser , also enhanced nicotine self-administration in animals in which MAO activity was inhibited ; ( 3 ) pretreatment with tranylcypromine increased PCA-induced 5-HT overflow in the nucleus accumbens .
[["nicotine", "ketanserin", "COMB"], ["nicotine", "parachloroamphetamine", "COMB"], ["nicotine", "ritanserin", "COMB"]]