I first did a search for 'medical research search engine' and found several.
One of those was MedScape, which came up with the result:
Transient Blindness Due to Posterior
Reversible Encephalopathy Syndrome
Following Ephedra Overdose
used in the presented patient.1 Both
supplements are based on the ECA stack
containing ephedrine, caffeine and
aspirin which are used for their ...
Reading the article, the reference to ECA stack states:
Both supplements are based on the ECA
stack containing ephedrine, caffeine
and aspirin which are used for their
synergistic thermogenic properties.
Which references the paper:
Daly PA, Krieger DR, Dulloo AG, et al.
Ephedrine, caffeine and aspirin:
safety and efficacy for treatment of
human obesity. Int J Obes Relat Metab
Disord 1993;17(suppl 1):S73-S78.
So, perhaps this paper would contain what you are looking for or you could even try contacting Krieger or Dulloo.
A search on pogofrog for 'ECA stack' turned at least one interesting result:
ISSN Exercise & Sport Nutrition
Review: Research & Recommendations
J Int Soc Sports Nutr. 2004; 1(1):
Published online 2004 May 10. doi:
Richard B Kreider,corresponding
author1 Anthony L Almada,2 Jose
Antonio,3 Craig Broeder,4 Conrad
Earnest,5 Mike Greenwood,1 Thomas
Incledon,6 Douglas S Kalman,7 Susan M
Kleiner,8 Brian Leutholtz,1 Lonnie M
Lowery,9 Ron Mendel,10 Jeffrey R
Stout,11 Darryn S Willoughby,1 and Tim
which referenced several research papers on the ECA Stack which may provide a lead to a scientist who can provide the answer you seek.
This, perhaps, isn't the answer you want, but it may lead to you the answer.