To fully grasp the complexity surrounding heparin, it is important to understand its classification. Heparin can be classified based on its molecular weight and source, providing valuable insights into its pharmacological properties and applications.

　　Molecular Weight Classification: Heparin is classified into two categories based on its molecular weight - unfractionated heparin (UFH) and low molecular weight heparin (LMWH). UFH consists of a heterogeneous mixture of polysaccharide chains, whereas LMWH has smaller, more uniform chains. This difference impacts their pharmacokinetics and dosing regimens.

　　Source Classification: Heparin is derived from natural sources, primarily porcine (pig) intestines and bovine (cow) lung tissues. Porcine heparin is more widely used due to its higher availability and similarities to human heparin. Bovine heparin is less common but can be an alternative source.

　　Subclassifications: Within the LMWH category, various subtypes exist, such as enoxaparin, dalteparin, and tinzaparin. These LMWHs differ in their molecular weight, pharmacokinetics, and specific indications. Understanding these subclassifications enables healthcare professionals to select the most appropriate agent for a particular patient.