Oral dosage form physicochemical property

In summary, the effect of pH on the dissolution rate of a drug from an oral dosage form depends on (a) the pH of the GI fluids, a patient variable (b) the acid or base strength of the drug, a pharmaceutical variable as well as (c) the physicochemical properties of the dosage form, another pharmaceutical variable. Furthermore, by intentionally designing the dosage form such that it buffers the diffusion layer, we can control a patient variable by a pharmaceutical variable. 

A rational approach to dosage form design requires a complete understanding of the physicochemical and biopharmaceutical properties of the drug substance. For example, the successful design of an efficacious oral dosage form requires an understanding of the... 

Early on in product development, the potential for the successful development of a solid oral dosage form is assessed, based on the physicochemical properties of the API (1). Prior to solid dosage form development, it is necessary to anticipate the physicochemical properties that can have a major influence on product manufacture and performance. The early development (preformulation and early formulation development) studies should focus on these properties so as to avoid problems at later stages of development. While the molecular properties dictate the intrinsic solubility and the chemical stability of the compound, by controlling the physical form of the compound and by modifying physical properties (e.g., particle size), the dissolution rate can be enhanced with the potential for improving bioavailability. This chapter will focus on physical properties including particle characteristics, and most importantly, the physical form (i.e., solid state) of the API. 

During the preformulation and formulation stages of a parenteral dosage form, the physicochemical properties and excipient compatibility of the pharmaceutical active ingredient (API) should be thoroughly evaluated. The test method requirements are similar to those for oral dosage forms. 

All product characteristics likely to be affected by storage, e.g., assay value or potency, content of products of decomposition, physicochemical properties (hardness, disintegration, particulate matter, etc.), should be determined for solid or semi-solid oral dosage forms, dissolution tests should be carried out... 

Orally administered dosage forms are absorbed into the systemic circulation following dissolution in the GI tract. Because substances must be in solution for the absorption from the GI lumen, the absorption rate of poorly water-soluble drugs is limited by their rate of dissolution. The dissolution rate is affected by the unique physicochemical properties of the drug and by physiological factors the pH, composition, and hydrodynamics of the GI medium. 

To date, the challenges associated with development of an oral MR dosage form for water-insoluble drugs have not been systematically studied and discussed. In many cases, the physicochemical properties of the drug and its sensitivity to the conditions of the Gl track make it more difL cult to attain the desired absorption and PK proLle. This is a clear point of concern in developing a MR product for poorly water-soluble drugs. 

On the way to multiple-unit dosage forms, a demand is seen for flexible polymers. These polymers can be summed up in a new class of polymers that have at least two main functions They have the functionality for enteric targeting and they show physicochemical properties necessary to obtain the desired flexibility. A new market can be seen in this field for the manufacture of coating materials, because the functionality of these polymers should not be limited to enteric targeting but also be applicable to other fields of controlled release, like transdermal applications or oral sustained-release dosage forms. 

Pharmaceutical excipients available on the market seem sufficient to support typical oral solid dosage form development. In some cases, new chug candidates have physicochemical and biopharmaceutical properties that are less than ideal. These chugs present formulation challenges and may require either the discovery of new excipients or improvement of existing excipients. From a regulatory perspective, there is no answer for the question of registration of an excipient as a separate entity. 

Most of the dosage forms of the bioactive protein or peptide are liquid preparations. The permeability of the intestinal mucosa to high-molecular-weight substances is very low. However, oral delivery systems may be developed by manipulation of the physicochemical property of the drug molecule or by devising an effective formulation. 

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