A randomized placebo-controlled study of the effect of low dose aspirin on platelet reactivity and serum thromboxane B2 production in non-pregnant women, in normal pregnancy, and in gestational hypertension.
OBJECTIVE
To investigate the effect of 60 mg aspirin daily on platelet reactivity and prostaglandin production in various groups of patients. Similar regimens, which are thought to act through inhibition of platelet thromboxane production, are currently undergoing clinical assessment for the prevention of pre-eclampsia and intrauterine growth retardation.


METHODS
A prospective randomized placebo controlled study.


METHODS
University Hospital, Nottingham.


METHODS
12 non-pregnant female volunteers, 18 normal primigravidae before 16 weeks gestation and 16 pregnant women admitted with gestational hypertension (GH) at a mean gestation of 38 weeks.


METHODS
In the non-pregnant women blood samples were taken before and after a 10-day course of 60 mg aspirin daily. The primigravidae had blood samples taken at 16 weeks and then they were randomized to receive either 60 mg aspirin daily or a matched placebo. Further blood samples were obtained at 28, 32 and 36 weeks.


METHODS
Changes in platelet reactivity and release reaction, and serum thromboxane production, were estimated in whole blood.


RESULTS
60 mg aspirin daily significantly inhibited cyclo-oxygenase dependent platelet aggregation, release reaction and serum thromboxane production in non-pregnant and pregnant women, and in women with GH (P less than 0.01). When adrenaline was used as the aggregating agent, the cyclo-oxygenase pathway was recruited in the increased reactivity seen in the third trimester of normal pregnancy, and was sensitive to inhibition by low dose aspirin.


CONCLUSIONS
Low dose aspirin would appear to be an appropriate agent for the inhibition of platelet reactivity associated with hypertensive pregnancy.
Louden
K A
KA
Department of Obstetrics and Gynaecology, University Hospital, Nottingham, UK.
Broughton Pipkin
F
F
Symonds
E M
EM
Tuohy
P
P
O'Callaghan
C
C
Heptinstall
S
S
Fox
S
S
Mitchell
J R
JR
D000328:Adult; D016718:Arachidonic Acid / Q000494:pharmacology; D001241:Aspirin / Q000008:administration & dosage* / Q000494:pharmacology; D003094:Collagen / Q000494:pharmacology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D011247:Pregnancy / Q000097:blood*; D011249:Pregnancy Complications, Cardiovascular / Q000097:blood*; D013929:Thromboxane B2 / Q000378:metabolism*
D010975:Platelet Aggregation Inhibitors; D016718:Arachidonic Acid; D013929:Thromboxane B2; D003094:Collagen; D001241:Aspirin