Rate Of Gastrointestinal Absorption Research Articles

Increasing Dissolution Rates and Gastrointestinal Absorption of Drugs Via Solid Solutions and Eutectic Mixtures I: Theoretical Considerations and Discussion of the Literature

The theoretical aspects of solid solutions and eutectic mixtures as well as their application to pharmaceutical systems are discussed. A mechanism is considered by which such solid systems may enhance dissolution rates and, in turn, the gastrointestinal absorption rate and availability of poorly soluble drugs. A degree of ambiguity exists in the literature published to date in this area. This report proposes that results previously attributed to eutectic mixtures are properly explained by the existence of solid solutions. The sulfathiazole–urea and chloramphenicol-urea systems are examined in detail.

The influence of solubility on the rate of gastrointestinal absorption of aspirin.

The blood plasma concentration of salicylate 10, 20, 30, 45, and 60 minutes following the oral ingestion of 0.64 Gm. of aspirin in various pharmaceutical preparations was determined in a total of 168 experiments on 55 normal human subiects and used as an index of the rate of gastrointestinal absorption. Aspirin was absorbed relatively slowly, maximum blood levels not being attained at the end of 60 minutes. "Buffered" LWpirin preparations containing aluminum and magnesium "buffers" were somewhat more rapidly absorbed, maximum blood levels being attained at 30 to 45 minutes. A commercially available etfervescent preparation containing aspirin, which must be dissolved prior to ingestion, was still more rapidly absorbed, yielding maximum blood levels at 20 to 30 minutes. Similar results were obtained when aspirin was dissolved in hot water. To extend these observations soluble sodium acetylsalicylate was prepared by neutralizing aspirin with an equivalent amount of sodium bicarbonate. This was also rapidly absorbed. It is concluded that the rate of gastrointestinal absorption of aspirin is markedly influenced by solubility.

Symposium on clinical drug evaluation and human pharmacology. XVII. Physicochemical and pharmaceutic properties of drugs that influence the results of clinical trials.

Despite the fact that pharmacologists and some clinicians are aware that physical, chemical, and pharmaceutic properties of a drug may influence its actions and effects, little consideration has been given to quantitating the effects of these properties. It is the aim of this article to discuss and illustrate the fact that the rate of gastrointestinal absorption of a drug is often a function of the time needed for the drug to dissolve in the fluid at the site of absorption. Clinical trials of several forms of the same drug may merely confirm a result which should have been predicted on the basis of its properties, such as specific surface area, type of salt, and the form in which it is administered.

Comparison of the Gastrointestinal Absorption of Aluminum Acetylsalicylate and Acetylsalicylic Acid in Man

The gastrointestinal absorption rate and biological availability of aluminum acetylsalicylate have been studied in human subjects by the urinary excretion method. Acetylsalicylic acid absorption from orally administered aluminum acetylsalicylate was found to be less rapid than from aspirin, probably due to the very slow dissolution of the aluminum salt in gastrointestinal fluids. In the form used in this study, aluminum acetylsalicylate was incompletely absorbed after oral administration. Dosage forms containing this drug must be carefully evaluated with respect to absorption rate and biological availability.

Comparison of acute hypoglycemic potencies of tolbutamide and chlorpropamide.

Tolbutamide and chlorpropamide were compared as to their intrinsic hypoglycemic action by statistical analysis of data obtained from 21 diabetic patients. The hypoglycemic agents, usually taken orally, were administered intravenously to avoid their possible differences in rate or completeness of gastrointestinal absorption. The blood specimens were drawn from the patients during three hours after administration of the drugs to assure comparison of their hypoglycemic effect at a time when the plasma concentrations would be similar. The specimens were analyzed for blood glucose and plasma levels of the two drugs. Each patient was tested once with each drug. The two drugs were found not to differ in their acute hypoglycemic potencies, and the need for a greater dosage of tolbutamide in long-term therapy is most likely explained by its more rapid rate of inactivation and excretion.

Uptake of radioactive iodine after intravenous administration of tracer doses.

AFTER oral administration of radioactive iodine, the uptake of the tracer by the thyroid gland is abnormally high in most cases of untreated hyperthyroidism (1, 2, 3). However, a significant overlap exists between the normal range of uptake and the range in hyperthyroidism (4, 5); cases with uptakes in the range of overlap must be considered borderline. Since it is in these borderline cases that the clinician has most difficulty in establishing the correct diagnosis, any safe procedure which would reduce the area of overlap would be welcome. It seemed desirable to determine if this purpose might be accomplished by administering the tracer intravenously, thereby eliminating the variables of rate and amount of gastrointestinal absorption. It was also hoped that the intravenous method would offer the additional advantages of rapidity and convenience.