The effect of pre-induction clonidine on platelet aggregation during minor surgery.
OBJECTIVE
This paper reports the results of a prospective randomized double-blind trial on the effects of pre-operative clonidine on platelet aggregation.


METHODS
Thirty adult (ASA I-II) patients undergoing elective minor orthopaedic surgery were randomly allocated into three groups of ten patients each. In group I clonidine 2 microg x kg(-1), in group II clonidine 4 microg x kg(-1) and in group III saline placebo was administered intravenously before the induction of anaesthesia. Anaesthesia was induced with propofol and vecuronium and maintained with halothane-nitrous oxide. Platelet counts and aggregation tests were performed before (t0) and 1 h (t1) and 24 h (t24) after administration of the study drug.


RESULTS
Changes in platelet counts among the groups and values over time were not significant. Both maximum rate and intensity of collagen-induced aggregation in both clonidine groups and maximum intensity of adenosine 5'-diphosphate (ADP)-induced aggregation in the high-dose clonidine group increased significantly at t1. However, all these increases in aggregation were within the normal ranges.


CONCLUSIONS
The effects of both low and high doses of clonidine on platelet aggregation appeared to be minor, and we did not observe any increases above the normal ranges.
Department of Anaesthesiology, Hacettepe University Medical School, Ankara, Turkey.
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EA
Akpek
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Kahraman
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Yaman
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Bulutçu
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Yavuzer
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Ozgen
D000328:Adult; D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D003000:Clonidine / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013511:Minor Surgical Procedures; D009985:Orthopedics; D010974:Platelet Aggregation / Q000187:drug effects*; D011446:Prospective Studies
D000700:Analgesics; D003000:Clonidine