852

alteplase and urokinase were comparable. You recommend that "a more fair comparison would be 1 million units of urokinase given intravenously over 10 min followed by 2 million units over the next 110 min". The results of such a comparative study already exist. After having been criticised for his first comparative study, Goldhaber’ conducted a second study that exactly followed your suggestions. 86 patients with angiographically proven pulmonary embolism were included. In this exceptionally large patient population, 44 patients were given 1 million units of urokinase over 10 min followed by 2 million units over 110 min. This group was compared with 42 patients received 100 mg of rt-PA over 2 h. Infusions were always given via peripheral veins. Although the dosage of urokinase was lower than the dose Gaffney and Thomas thought to be equivalent, the control angiogram after 2 h showed an improvement in 66% of patients treated with urokinase and in 79% treated with rt-PA (p = 0 19). Changes in the perfusion scintigram after 24 h were equal in both groups (p=0’55). 2 patients in the you ask whether the doses of

rt-PA group and 1 in the other group had an intracerebral haemorrhage. Goldhaber et al concluded that urokinase applied at this new dosage was similarly effective and as safe as rt-PA. Thus urokinase could be viewed as at least as efficacious as rt-PA, with urokinase being by far the less expensive alternative. University Clinic for Anaesthesiology, Ruprecht-Karls-Universitat Heidelberg, 6900 Heidelberg, Germany Time-course and treatment after delivery in thrombotic thrombocytopenic purpura.

woman

B. W. BÖTTIGER H. BÖHRER

with

Plateletcount(10’/I) isshown in log scale on the ordinateaxis Day 0=onset of labour, P=plasma exchange Sustained rise in platelet count (and clinical recovery) was not seen until mtroduction of antiplatelet therapy

1 Goldhaber

2

3.

blood count (without film) 36 h later was normal. Her day 7 count, however, showed thrombocytopenia (platelets 30 x 109/1). Clotting

SZ, Kessler CM, Heit J, et al Randomised controlled trial of recombinant plasminogen activator versus urokinase in the treatment of acute pulmonary embolism Lancet 1988; ii. 293-98. Meyer G, Sors H, Carbonnier B, et al Effects of intravenous urokinase versus alteplase on total pulmonary resistance in acute massive pulmonary embolism a European multicenter double-blind trial. J Am Coll Cardiol 1992; 19: 239-45. Gaffney PJ, Thomas DP Urokinase versus tissue plasminogen activator in pulmonary tissue

embolism. Lancet 1988, ii: 692. 4 Goldhaber SZ, Kessler CM, Heit JA, et al TPA versus urokinase in acute pulmonary embolism a randomized controlled trial. Circulation 1991, 84 (suppl II) 357.

screen, biochemical tests, direct

Coomb’s test, and anti-nuclear normal and the blood film was microangiopathic. Purpura, malaise, and cerebral symptoms developed over the next 4 days and treatment was started. None of many standard and experimental treatments for her condition had any more than a fleeting impact (figure) and she continued to deteriorate until antiplatelet therapy (aspirin 75 mg once daily and oral dipyridamole 150 mg thrice daily) was started. She subsequently made a complete recovery and has remained in remission for 5 years (dipyridamole was withdrawn at 4 months, aspirin at 22 months). She has not undertaken any further pregnancies. We agree that fresh frozen plasma is the first-line treatment for this serious condition but wonder whether sequential or elective use of antiplatelet therapy with aspirin should be undertaken rather than vincristine in view of its oral administration and more favourable side-effect profile, especially in long-term use. factor

were

Division of Haematology, United Medical and Dental Schools of Guy’s and St Thomas’ Hospitals, St Thomas’s Hospital, London SE1 7EH, UK

PAUL REVELL N. G. P. SLATER

Food intake and

platelet aggregability

SIR,-Platelet aggregability in vitro is useful for estimating activity of antiplatelet drugs, which are widely used for

in-vivo

prevention andlor treatment of coronary heart disease and obstructive peripheral diseases. 1-3 The turbidimetric method4 uses an aggregometer, which monitors changes in optical densities during and after addition of aggregation-inducing agents (eg, adenosine diphosphate [ADP], collagen, adrenaline) to a plateletrich plasma. Hence hyperlipidaemic plasma samples taken postprandially are regarded as unsuitable because of possible interference by such turbid plasma. Nevertheless, a patient may commonly have eaten beforehand. We studied the effect of breakfast (622 kcal, protein 19-1 g, lipid 25-8 g, and carbohydrate 78-3 g) on induced platelet aggregation4 with a Hematracer 801 (Niko Bioscience, Tokyo, Japan) in 5 normal men after obtaining informed consent. The study began at 1000 h after an overnight fast. Intake of beverages containing alcohol or methylxanthines and PLATELET AGG R EGABI LITY BEFORE AND AFTER

Thrombolysis for pulmonary embolism SiR,—In your July 4 editorial you state that, until now, there has been

no unequivocal study comparing recombinant tissue plasminogen activator (rt-PA; alteplase) and urokinase for thrombolysis of pulmonary embolism. Goldhaber et all and Meyer et al52 who you cite, used different durations of drug application (rt-PA 2 h, urokinase for, respectively, 24 h and 12 h). Therefore, whether the advantage of rt-PA that was apparent in the early phase was due to the substance itself or to the initially higher dosage and thus higher thrombolytic potency is unclear. According to Gaffney and Thomas,3 the biological activity of the rt-PA dose used by

Goldhaber

et

al is

some seven

times

more

than the urokinase dose

they used. With respect to Goldhaber’s and Meyer’s investigations,

Mean

(SD) optical density shown

BREAKFAST

Thrombolysis for pulmonary embolism.

852 alteplase and urokinase were comparable. You recommend that "a more fair comparison would be 1 million units of urokinase given intravenously ove...
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