Ancrod, a drug derived from snake venom, is not effective in the treatment of ischaemic stroke if given within a 6 hour window after the onset of symptoms, according to the results of a randomised trial published in this week’s issue of The Lancet.
Ancrod contains a purified fraction of venom from the Malaysian pit viper. It is a promising biological agent that acts on blood’s ability to clot. A previous trial has shown that ancrod has a favourable effect on ischaemic stroke when given within a 3 hour window.
In the European Stroke Treatment with Ancrod Trial (ESTAT), Michael Hennerici and colleagues assessed the effect of ancrod when given within 6 hours. The investigators randomly assigned 1222 patients from Europe, Australia, and Israel, ancrod (604) or a placebo (618). They found that functional ability was much the same in the active treatment group as in the control group. Neurological recovery was worse and there were more haemorrhages in the ancrod group than in the placebo group. Mortality at 3 months was higher in the ancrod group than in the placebo group but at 12 months there was no significant difference. The authors state that most patients were included beyond 3 hours after onset of stroke and this is likely to be the main reason that no benefit was shown for ancrod.
Professor Hennerici concludes: “On the basis of our findings, ancrod should not be recommended for use in acute ischaemic stroke beyond 3 hours.”
In an accompanying Comment Markku Kaste (University of Helsinki, Finland) states: “Although the study was unsuccessful, it delivers an important message: that time from onset of symptoms to treatment matters, and in ESTAT it was too long. The study also highlights how important it is to publish unsuccessful trials. Such trials often include valuable pieces of information, which can guide future studies. Furthermore, it is unethical not to publish the results of all well-designed and executed trials just because they fail to reach their targets.”
Contact: Professor Michael G Hennerici, Neurologische Univ. Klinik Mannheim, Theodor-Kutzer-Ufer, 68135 Mannheim, Germany. T) +49 621 383 2885 hennerici@neuro.ma.uni-heidelberg.de
Professor Markku Kaste, Department of Neurology, Helsinki University Central Hospital, University of Helsinki, Haartmaninkatu 4, PO Box 340, FI-00290, Helsinki, FINLAND. T) +358 9 471 72260 markku.kaste@hus.fi
Journal
The Lancet