Pharmacological effects of hordenine]. - [Article in German]; Hapke HJ, Strathmann W;  Institut für Pharmakologie, Toxikologie und Pharmazie, Tierärztlichen Hochschule Hannover.
…... Results of some experiments in pharmacological models show that hordenine is an indirectly acting adrenergic drug.
It liberates norepinephrine from stores. In isolated organs and those structures with reduced epinephrine contents the hordenine-effect is only very poor.
Experiments in intact animals (rats, dogs) show that hordenine has a positive inotropic effect upon the heart, increases systolic and diastolic blood pressure, peripheral blood flow volume, inhibits gut movements but has no effect upon the psychomotorical behaviour of mice.
All effects are short and only possible after high doses

Hordenine: pharmacology, pharmacokinetics and behavioural effects in the horse. - Frank M, Weckman TJ, Wood T, Woods WE, Tai CL, Chang SL, Ewing A, Blake JW, Tobin T.; Kentucky Equine Drug Research Program, Graduate Center in Toxicology, University of Kentucky, Lexington 40506.
Hordenine is an alkaloid occurring naturally in grains, sprouting barley, and certain grasses. It is occasionally found in post race urine samples, and therefore we investigated its pharmacological actions in the horse.
Hordenine (2.0 mg/kg bodyweight [bwt]) was administered by rapid intravenous (iv) injection to 10 horses. Typically, dosed horses showed a flehmen response and defecated within 60 secs.
All horses showed substantial respiratory distress. Respiratory rates increased about 250 per cent and heart rates were approximately double that of resting values. All animals broke out in a sweat shortly after iv injection, but basal body temperature was not affected. These effects were transient, and the animals appeared normal within 30 mins of dosing. Treated horses were tested in a variable interval responding apparatus 30 mins after dosing and no residual stimulation or depressant effects of hordenine were apparent.

Extract from Certification of standard reference materials containing bitter orange - Sander LC et National Institute of Standards and Technology, Chemical Science and Technology Laboratory, , Gaithersburg, USA.
A suite of three dietary supplement standard reference materials (SRMs) containing bitter orange has been developed, and the levels of five alkaloids and caffeine have been measured by multiple analytical methods.

• Synephrine
• Octopamine
• Tyramine
• N-methyltyramine
• Hordenine
• total alkaloids
• and caffeine

were determined by as many as six analytical methods, with measurements performed at the National Institute of Standards and Technology and at two collaborating laboratories. The methods offer substantial independence, with two types of extractions, two separation methods, and four detection methods. Excellent agreement was obtained among the measurements, with data reproducibility for most methods and analytes [sic] better than 5% relative standard deviation. The bitter-orange-containing dietary supplement SRMs are intended primarily for use as measurement controls and for use in the development and validation of analytical methods.

PMID: 18425642