Adenosine

Absorption

Data regarding the absorption of adenosine are not readily available.

Toxicity

Patients experiencing an overdose of adenosine may present with asystole, heart block, or cardiac ischemia; though the effects are generally short lived. Patients experiencing an overdose should be treated with symptomatic and supportive care, which may include a slow intravenous injection of theophylline.
The LD50 in mice is >20 g/kg subcutaneously, 500mg/kg intraperitoneally, and 39.6 μg/kg subcutaneously.

Description

Adenosine is a nucleoside composed of a molecule of adenine attached to a ribose sugar molecule (ribofuranose) moiety via a β-N9-glycosidic bond. Adenosine works in the energy transfer-as adenosine triphosphate (ATP) and adenosine diphosphate (ADP)-as well as in signal transduction as cyclic adenosine monophosphate, cAMP. It shows neuromodulatory, cytoprotective, anti-inflammatory and cardioprotective actions.

Description

Adenosine is a nucleoside found widely in nature, and it is one of the components of the important energy-transfer coenzymes adenosine triphosphate (ATP) and diphosphate (ADP). It was first isolated from yeast nucleic acid; several researchers reported its structure in the 1930s. More recently, M. Nedergaard and co-workers showed that adenosine released during acupuncture acts as a painkiller.

The Uses of Adenosine

adenosine is an amino acid. Studies indicate anti-wrinkle and skinsmoothing capacities. Although little is written about its direct skin benefit, adenosine plays an important role in biochemical processes. As adenosine triphosphate (ATP) and adenosine diphosphate (ADP), it is involved in energy transfer, and as cyclic adenosine monophosphate (cAMP) in signal transduction.

What are the applications of Application

Adenosine is an apoptosis inducer and an Adenosine A Receptor activator

Indications

Adenosine is indicated as an adjunct to thallium-201 in myocardial perfusion scintigraphy in patients unable to adequately exercise. It is also indicated to convert sinus rhythm of paroxysmal supraventricular tachycardia.

Background

The structure of adenosine was first described in 1931, though the vasodilating effects were not described in literature until the 1940s. Adenosine is indicated as an adjunct to thallium-201 in myocardial perfusion scintigraphy, though it is rarely used in this indication, having largely been replaced by dipyridamole and [regadenson]. Adenosine is also indicated in the treatment of supraventricular tachycardia.
Adenosine was granted FDA approval on 30 October 1989.

Pharmacokinetics

Adenosine is indicated as an adjunct to thallium-201 in myocardial perfusion scintigraphy and also indicated for conversion of sinus rhythm of paroxysmal supraventricular tachycardia. Adenosine has a short duration of action as the half life is <10 seconds, and a wide therapeutic window. Patients should be counselled regarding the risk of cardiovascular side effects, bronchoconstriction, seizures, and hypersensitivity.

Metabolism

Adenosine can be phosphorylated by adenosine kinase to form adenosine monophosphate. From there, it is phosphorylated again by adenylate kinase 1 to form adenosine diphosphate, and again by nucleoside diphosphate kinase A or B to form adenosine triphosphate.
Alternatively, adenosine can be deaminated by adenosine deaminase to form inosine. Iosine is phosphorylated by purine nucleoside phosphorylase to form hypoxanthine. Hypoxanthine undergoes oxidation by xanthine dehydrogenase twice to form the metabolites xanthine, followed by uric acid.