It can be distinguished by its pale color when stained with haematoxylin and eosin. The presence of odontoblastic processes here allows the secretion of matrix components. Predentin can be 10-40μm in width, depending on its rate of deposition. : 134–137

Types
There are three types of dentin, primary, secondary and tertiary. Secondary dentin is a layer of dentin produced after the root of the tooth is completely formed. Tertiary dentin is created in response to a stimulus, such as a carious attack or wear. Primary dentin
Primary dentin, the most prominent dentin in the tooth, lies between the enamel and the pulp chamber (near dentinoenamel junction). The outer layer closest to enamel is known as mantle dentin. This layer is unique to the rest of primary dentin. Mantle dentin is formed by newly differentiated odontoblasts and forms a layer consistently 15-20 micrometers (µm) wide. Unlike primary dentin, mantle dentin lacks phosphorylation, has loosely packed collagen fibrils and is less mineralized. Below it lies the circumpulpal dentin, more mineralized dentin which makes up most of the dentin layer and is secreted after the mantle dentin by the odontoblasts. Circumpulpal dentin is formed before the root formation is completed. Newly secreted dentin is unmineralized and is called predentin. It is easily identified in hematoxylin and eosin stained sections since it stains less intensely than dentin. It is usually 10-47μm and lines the innermost region of the dentin. It is unmineralized and consists of collagen, glycoproteins, and proteoglycans. It is similar to osteoid in bone and is thickest when dentinogenesis is occurring.
Trandolapril has a half-life of about 6 hours, and trandolaprilat has a half life of about 10 h. Trandolaprilat has about eight times the activity of its parent drug. About one-third of trandolapril and its metabolites are excreted in the urine, and about two-thirds of trandolapril and its metabolites are excreted in the feces. Serum protein binding of trandolapril is about 80%. Mode of action
Trandolapril acts by competitive inhibition of angiotensin converting enzyme (ACE), a key enzyme in the renin–angiotensin system which plays an important role in regulating blood pressure. References
External links
Trandolapril Information - rxlist.com (Rxlist.com, The Internet Drug Index)