Heparin sodium is the salt of heparinic acid, which is known to be unstable. There are various other salts available, but the sodium salt is most commonly used as an anticoagulant. It is biosynthesized and stored in mast cells of various mammalian tissues, particularly liver, lung and mucosa. Commercial heparin is chiefly isolated from beef lung or porcine intestinal mucosa. It may be dissolved in water, saline or buffer. It is available from Akron Biotech in lyophilized form.