title: Abnormally high platelet activity after discontinuation of acetylsalicylic acid treatment.
abstract: Production of 12-L-hydroxy-5, 8, 10-heptadecatrienoic acid (12-HHT) from platelets and bleeding times were studied in 32 males during acetylsalicylic acid (ASA) treatment and 1 and 2 weeks after withdrawal. All patients (age 42-77 years) had ASA treatment because of angina pectoris. The metabolite 12-HHT is formed in the same amount as the proaggregatory and vasoactive metabolite thromboxane A2. Initially the daily ASA dose was 75 mg (n = 15), 160 mg (n = 12) or 250-300 mg (n = 5). In all patients, median 12-HHT level increased from 40 to 240g/750 x 10(6) platelets (P < 0.001) 1 week after withdrawal of ASA, and four patients had abnormally high values. Median bleeding time decreased from 312 to 268 s (P = 0.003) in the 75 mg group and from 315 to 235 s in the 160 mg group (P = 0.01). Two weeks after withdrawal of ASA, median 12-HHT was 390g/750 x 10(6) platelets and eight patients (25%) had abnormally high values. One patient still had a prolonged bleeding time. Wide interindividual variations were observed in all groups. Our results indicate that rapid withdrawal of ASA, may cause abnormally high 12-HHT levels reflecting increase of thromboxane A2 with possible hazardous effects in patients with cardiovascular disease.
authors.affiliation: Department of Experimental Surgery, Thoracic Clinics, Karolinska Hospital, Stockholm, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Beving
authors.forename: C
authors.initials: C
authors.lastname: Zhao
authors.forename: A
authors.initials: A
authors.lastname: Albåge
authors.forename: T
authors.initials: T
authors.lastname: Ivert
mesh_terms: D000328:Adult; D000368:Aged; D001241:Aspirin / Q000009:adverse effects*; D001760:Bleeding Time; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000009:adverse effects*; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010976:Platelet Count / Q000187:drug effects; D016896:Treatment Outcome
chemical_list: D016861:Cyclooxygenase Inhibitors; D005231:Fatty Acids, Unsaturated; C008033:12-hydroxy-5,8,10-heptadecatrienoic acid; D001241:Aspirin