Gastrointestinal dissolution

Hotter, D., Dressman, J. B. Influence of physicochemical properties on dissolution of drugs in the gastrointestinal tract. Adv. Drug Deliv. 

Pancreatic enzyme replacement is the mainstay of gastrointestinal therapy. Most enzyme products are formulated as capsules containing enteric-coated microspheres or microtablets to avoid inactivation of enzymes in the acidic stomach instead, they dissolve in the more alkaline environment of the duodenum. Capsules may be opened and the microbeads swallowed with food, as long as they are not chewed. A powder form is available for patients unable to swallow the capsules or microbeads, but bioavailability is poor. While products may contain similar enzyme ratios, they are not bioequivalent and cannot be substituted. Generic enzyme products generally display poor dissolution and should not be used.5 Table 13-3 lists commonly used enzyme replacement products. 

Returning to Fig. 6, it can be seen that the oral administration of two 15-mg tablets of propantheline 1.5 hours before atenolol delayed the rate of availability of this p-blocker, while increasing its extent of availability [11]. This increased extent might be due to more complete dissolution of the drug, resulting from its increased time in the gastrointestinal tract. 

Disintegration Dissolution Flowability Compressibility (Gastrointestinal bleeding)... 

An interesting paper that attempted to relate dissolution of a poorly soluble acidic drug (naproxen) to simulated gastrointestinal flow in the presence of buffers was published by Chakrabarti and Southard [17]. In addition to showing that buffer type (citrate, phosphate, or acetate) had a significant impact on naproxen dissolution, these authors unexpectedly found that elevating a solid tablet into the flow channel of the flow-between-two-plates apparatus resulted in a substantial... 

S Chakrabarti, MZ Southard. Control of poorly soluble drug dissolution in conditions simulating the gastrointestinal tract flow. 1. Effect of tablet geometry in buffered medium. J Pharm Sci 85 313-319, 1996. 

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