Arachidonic-acid-induced platelet aggregation

Where it participates (unsigned role)

1. Ibuprofen but not celecoxib significantly inhibited thromboxane-dependent platelet aggregation induced ex vivo by arachidonic acid, 83% against 11.9%, and reduced serum thromboxane B2 by 95% and urinary 11-dehydro thromboxane B2 by 70%, while both ibuprofen and celecoxib suppressed an index of cyclooxygenase-2 activity to a comparable degree and both suppressed urinary excretion of the prostacyclin metabolite 2,3-dinor-6-keto-prostaglandin F1 alpha, data suggesting that cyclooxygenase-2 is a major source of systemic prostacyclin biosynthesis in healthy humans.

   Ibuprofen → Systemic prostacyclin biosynthesis measured as urinary 2,3-dinor-6-keto-prostaglandin F1 alpha source_derived_draftungraded
   Experimental context and source evidence

   evidence_span

   {"source_cache": "artifacts/ibuprofen-research/9874808.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a643d03df8bc925866696516e7040644634dca29b4f98d39df38ea9c9ab295f4", "start_char": 0, "end_char": 1789, "text_sha256": "a643d03df8bc925866696516e7040644634dca29b4f98d39df38ea9c9ab295f4"}

   experimental_model

   Volunteers given celecoxib at three doses or ibuprofen, with platelet, serum and urinary indices

   exposure

   800 milligrams ibuprofen against 100, 400 or 800 milligrams celecoxib

   limitations

   Measures both isoform-specific indices in the same people, which is what allows the prostacyclin source to be assigned. Acute dosing in healthy volunteers.

   nutrient_topic

   Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. · Ibuprofen

   organism

   Human

   plain_language

   The enzyme these drugs are meant to spare the stomach by blocking is the one that makes the body’s main anticlotting prostaglandin.

   primary_references

   [ibu-p9874808] Systemic biosynthesis of prostacyclin by cyclooxygenase (COX)-2: the human pharmacology of a selective inhibitor of COX-2. (1999). https://pubmed.ncbi.nlm.nih.gov/9874808/ DOI: 10.1073/pnas.96.1.272

   tissue_or_cell_type

   Platelets and whole body

   Ibuprofen: the enantiomer that works, the one that was called inactive, the one-way chemistry that turns one into the other, and the targets that are not cyclooxygenase (2026-09-22) · lines 526–537

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Volunteers given celecoxib at three doses or ibuprofen, with platelet, serum and urinary indices · source_derived_draft · unverified_draft

   ### ibu-cox2-makes-the-prostacyclin Ibuprofen but not celecoxib significantly inhibited thromboxane-dependent platelet aggregation induced ex vivo by arachidonic acid, 83% against 11.9%, and reduced serum thromboxane B2 by 95% and urinary 11-dehydro thromboxane B2 by 70%, while both ibuprofen and celecoxib suppressed an index of cyclooxygenase-2 activity to a comparable degree and both suppressed urinary excretion of the prostacyclin metabolite 2,3-dinor-6-keto-prostaglandin F1 alpha, data suggesting that cyclooxygenase-2 is a major source of systemic prostacyclin biosynthesis in healthy humans. Condition category: normal nutrient_topic: Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. plain_language: The enzyme these drugs are meant to spare the stomach by blocking is the one that makes the body’s main anticlotting prostaglandin. organism: Human tissue_or_cell_type: Platelets and whole body experimental_model: Volunteers given celecoxib at three doses or ibuprofen, with platelet, serum and urinary indices limitations: Measures both isoform-specific indices in the same people, which is what allows the prostacyclin source to be assigned. Acute dosing in healthy volunteers. exposure: 800 milligrams ibuprofen against 100, 400 or 800 milligrams celecoxib evidence_span: {"source_cache": "artifacts/ibuprofen-research/9874808.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a643d03df8bc925866696516e7040644634dca29b4f98d39df38ea9c9ab295f4", "start_char": 0, "end_char": 1789, "text_sha256": "a643d03df8bc925866696516e7040644634dca29b4f98d39df38ea9c9ab295f4"} [ibu-p9874808] Systemic biosynthesis of prostacyclin by cyclooxygenase (COX)-2: the human pharmacology of a selective inhibitor of COX-2. (1999). https://pubmed.ncbi.nlm.nih.gov/9874808/ DOI: 10.1073/pnas.96.1.272

   Complete structured claim and evidence

2. The S(+) isomer of ibuprofen was 32-, 41- and 96-fold more potent than the R(-) isomer for inhibition of prostaglandin endoperoxide H synthase-1 activity, human platelet aggregation and serotonin secretion respectively, while on prostaglandin endoperoxide H synthase-2 the ibuprofen isomers showed no selectivity, and indomethacin, S(+)-ibuprofen and S(+)-naproxen were 6-, 27- and 5-fold more potent as inhibitors of synthase-1 than of synthase-2.

   S(+)-ibuprofen → R(-)-ibuprofen source_derived_draftungraded
   Experimental context and source evidence

   evidence_span

   {"source_cache": "artifacts/ibuprofen-research/11755111.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1dd77f4a1eebd7777285c424b1731f4744d0fa593e62cfbde0a92dbb6242b239", "start_char": 0, "end_char": 2074, "text_sha256": "1dd77f4a1eebd7777285c424b1731f4744d0fa593e62cfbde0a92dbb6242b239"}

   experimental_model

   Reporter and enzyme assays comparing ibuprofen isomers against naproxen and indomethacin across four readouts

   exposure

   S(+)- and R(-)-ibuprofen compared directly on cyclooxygenase-1 and -2, platelet function and nuclear receptor activation

   limitations

   The only record here that measures both enantiomers on the same panel, which is what makes the fold-differences meaningful. Several different assay systems are combined.

   nutrient_topic

   Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. · Ibuprofen

   organism

   Rat, human and sheep systems

   plain_language

   At the first enzyme one hand is thirty to ninety times stronger; at the second enzyme the two hands are indistinguishable.

   primary_references

   [ibu-p11755111] Activation of peroxisome proliferator-activated receptor isoforms and inhibition of prostaglandin H(2) synthases by ibuprofen, naproxen, and indomethacin. (2001). https://pubmed.ncbi.nlm.nih.gov/11755111/ DOI: 10.1016/s0006-2952(01)00822-x

   tissue_or_cell_type

   Transfected cells, hepatoma cells, platelets and purified enzyme

   Ibuprofen: the enantiomer that works, the one that was called inactive, the one-way chemistry that turns one into the other, and the targets that are not cyclooxygenase (2026-09-22) · lines 318–329

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Reporter and enzyme assays comparing ibuprofen isomers against naproxen and indomethacin across four readouts · source_derived_draft · unverified_draft

   ### ibu-thirty-two-fold-at-cox1 The S(+) isomer of ibuprofen was 32-, 41- and 96-fold more potent than the R(-) isomer for inhibition of prostaglandin endoperoxide H synthase-1 activity, human platelet aggregation and serotonin secretion respectively, while on prostaglandin endoperoxide H synthase-2 the ibuprofen isomers showed no selectivity, and indomethacin, S(+)-ibuprofen and S(+)-naproxen were 6-, 27- and 5-fold more potent as inhibitors of synthase-1 than of synthase-2. Condition category: normal nutrient_topic: Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. plain_language: At the first enzyme one hand is thirty to ninety times stronger; at the second enzyme the two hands are indistinguishable. organism: Rat, human and sheep systems tissue_or_cell_type: Transfected cells, hepatoma cells, platelets and purified enzyme experimental_model: Reporter and enzyme assays comparing ibuprofen isomers against naproxen and indomethacin across four readouts limitations: The only record here that measures both enantiomers on the same panel, which is what makes the fold-differences meaningful. Several different assay systems are combined. exposure: S(+)- and R(-)-ibuprofen compared directly on cyclooxygenase-1 and -2, platelet function and nuclear receptor activation evidence_span: {"source_cache": "artifacts/ibuprofen-research/11755111.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1dd77f4a1eebd7777285c424b1731f4744d0fa593e62cfbde0a92dbb6242b239", "start_char": 0, "end_char": 2074, "text_sha256": "1dd77f4a1eebd7777285c424b1731f4744d0fa593e62cfbde0a92dbb6242b239"} [ibu-p11755111] Activation of peroxisome proliferator-activated receptor isoforms and inhibition of prostaglandin H(2) synthases by ibuprofen, naproxen, and indomethacin. (2001). https://pubmed.ncbi.nlm.nih.gov/11755111/ DOI: 10.1016/s0006-2952(01)00822-x

   Complete structured claim and evidence