TABLE OF CONTENTS The most fundamental and critical objective of a tablet is to deliver the active ingredient into the human blood stream accurately and reproducibly. Essentially, a tablet should be considered as a consumable drug delivery device.
Most modern commercial drug tablets consist of two basic structural parts: the core and coating layer(s). The core of a typical drug tablet contains a mixture of one or more active pharmaceutical ingredient(s) (API) with a number of inactive ingredients identified as excipients, containing diluents, binders and lubricants. Drug tablets seldom consist of only the API. As a result, a tablet is a mechanical system consisting of various bonded functional and structural parts (e.g. core and coating layers). The main reasons for formulating a tablet product with excipients range from management of small dosage amounts of active ingredient to esthetic reasons of color and shape of a pharmaceutical product.
The spatial distribution of active pharmaceutical ingredients and excipients in a tablet as well as the properties of its coating layers(s) play critical roles in defining its performance as a drug delivery device. Also, structural tablet defects like pharmaceutical functional irregularities in API can therefore affect the primary therapeutic functions of a tablet. Both structure and defects of a tablet as well as its mechanical properties are closely related to the manufacturing processes employed in its production.
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