{"id":"df5f77b6-3ff6-51c2-8ed7-f1119867fd20","stable_key":"3238e4f0-8d45-5c72-8624-6e9a8b20527c:ibu-binding-differs-between-hands","predicate":"reported_comparison","statement":"After oral administration of 800 milligrams of racemic ibuprofen to six healthy male volunteers the mean time-averaged percentage unbound of the R(-) enantiomer was 0.419, significantly less than that of the S(+) enantiomer at 0.643, consistent with stereoselective plasma protein binding, and the unbound percentage of each enantiomer was concentration-dependent across the therapeutic range and influenced by the presence of its optical antipode.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"19c4139f-e9e8-5e35-8c1d-ba0982aedd9f","mechanism_event_label":"Less of the R form is free in the blood than the S form, and each changes the other.","subject":{"id":"07a563b8-3005-5217-9cc9-b76365f062c7","slug":"r-ibuprofen","display_name":"R(-)-ibuprofen","entity_type_key":"small_molecule"},"object":{"id":"04282f17-56c4-54a9-aa33-37bc4c537c87","slug":"s-ibuprofen","display_name":"S(+)-ibuprofen","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"19c4139f-e9e8-5e35-8c1d-ba0982aedd9f","stable_key":"3238e4f0-8d45-5c72-8624-6e9a8b20527c:ibu-binding-differs-between-hands-event","event_type":"observed_intervention","label":"Less of the R form is free in the blood than the S form, and each changes the other.","description":"After oral administration of 800 milligrams of racemic ibuprofen to six healthy male volunteers the mean time-averaged percentage unbound of the R(-) enantiomer was 0.419, significantly less than that of the S(+) enantiomer at 0.643, consistent with stereoselective plasma protein binding, and the unbound percentage of each enantiomer was concentration-dependent across the therapeutic range and influenced by the presence of its optical antipode.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"90ebf099-f2e7-59ec-8477-1c6c2c6cda83","slug":"plasma-protein-binding-ibu","display_name":"Unbound fraction of drug in plasma","entity_type_key":"cellular_process"},"role":"measured_property","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"07a563b8-3005-5217-9cc9-b76365f062c7","slug":"r-ibuprofen","display_name":"R(-)-ibuprofen","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"04282f17-56c4-54a9-aa33-37bc4c537c87","slug":"s-ibuprofen","display_name":"S(+)-ibuprofen","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/ibuprofen-research/2744069.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"f73cd7aeb524ce11255efc7c629968dc35bafed4049636024dc2598c649ec858\", \"start_char\": 0, \"end_char\": 905, \"text_sha256\": \"f73cd7aeb524ce11255efc7c629968dc35bafed4049636024dc2598c649ec858\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Equilibrium dialysis with diastereomeric derivatisation and radiochemical analysis in six healthy male volunteers","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"800 milligrams racemic ibuprofen orally, with each enantiomer measured in the presence of the other","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Measures the two enantiomers in the presence of each other, which is the condition that actually obtains after a tablet. Six volunteers.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"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.","comparator":null,"unit":null,"notes":"","entity":{"slug":"ibuprofen","display_name":"Ibuprofen","entity_type_key":"drug"}},{"dimension":"organism","value_text":"Human","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Less of the R form is free in the blood than the S form, and each changes the other.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[ibu-p2744069] Stereoselective plasma protein binding of ibuprofen enantiomers. (1989). https://pubmed.ncbi.nlm.nih.gov/2744069/ DOI: 10.1007/bf00558161","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Plasma","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"d14642df-6f28-5b65-b4fe-93a1a519379e","evidence_kind":"source_excerpt","locator":"Lines 188-199","start_line":188,"end_line":199,"excerpt":"### ibu-binding-differs-between-hands\nAfter oral administration of 800 milligrams of racemic ibuprofen to six healthy male volunteers the mean time-averaged percentage unbound of the R(-) enantiomer was 0.419, significantly less than that of the S(+) enantiomer at 0.643, consistent with stereoselective plasma protein binding, and the unbound percentage of each enantiomer was concentration-dependent across the therapeutic range and influenced by the presence of its optical antipode.\nCondition category: normal\nnutrient_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.\nplain_language: Less of the R form is free in the blood than the S form, and each changes the other.\norganism: Human\ntissue_or_cell_type: Plasma\nexperimental_model: Equilibrium dialysis with diastereomeric derivatisation and radiochemical analysis in six healthy male volunteers\nlimitations: Measures the two enantiomers in the presence of each other, which is the condition that actually obtains after a tablet. Six volunteers.\nexposure: 800 milligrams racemic ibuprofen orally, with each enantiomer measured in the presence of the other\nevidence_span: {\"source_cache\": \"artifacts/ibuprofen-research/2744069.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"f73cd7aeb524ce11255efc7c629968dc35bafed4049636024dc2598c649ec858\", \"start_char\": 0, \"end_char\": 905, \"text_sha256\": \"f73cd7aeb524ce11255efc7c629968dc35bafed4049636024dc2598c649ec858\"}\n[ibu-p2744069] Stereoselective plasma protein binding of ibuprofen enantiomers. (1989). https://pubmed.ncbi.nlm.nih.gov/2744069/ DOI: 10.1007/bf00558161","model_system":"Equilibrium dialysis with diastereomeric derivatisation and radiochemical analysis in six healthy male volunteers","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [ibu-p2744069] Stereoselective plasma protein binding of ibuprofen enantiomers. (1989). https://pubmed.ncbi.nlm.nih.gov/2744069/ DOI: 10.1007/bf00558161","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"31c4939d-f520-55c0-973b-224743caf245","stable_key":"import-3238e4f0-8d45-5c72-8624-6e9a8b20527c","title":"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)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"cc2b388178f97f5906b66ecbe441fc5c86d51fd645947c5260fb0b4bdb4bcd21","revision_id":"0b4e5c65-05d3-5430-a4cd-8d6a03647dcb","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}