Acidic digestive fluids

Because of rich buccal vascularity, drugs delivered by the buccal route gain direct access to the systemic circulation and are not subject to first-pass metabolism. Also, therapeutic agents do not come in contact with the acidic digestive fluids secreted by the gastrointestinal tract. 

An average adult produces between 2 and 3 L of gastric juice daily. Gastric juice is an acidic digestive fluid secreted by glands in the mucous membrane that lines the stomach. It contains hydrochloric acid (HCI), among otho" substances. The pH of gastric juice is about 1.5, which... 

Its relatively low toxicity is probably the result of very low aqueous solubility (0.002 g/L) and lack of reactivity with acidic (HCl) digestive fluids. 

Serum and cerebrospinal fluid 206Pb addition and sample acid digestion lead isolation by ion-exchange, elution, and deposition onto platinum wire IDMS No data 80-120 Manton and Cook 1984... 

Water Acid digestion in mixture of nitric, sulfuric, and perchloric acids Electrothermal AAS 0.2 pg Ni/L fluids 98% at 5 pg Ni/L 97%at8pg Ni/L lARC 1986 (Method 11)... 

In the sulfite pulp process, the digestion fluid is typically made by dissolving sulfur dioxide in water in the presence of limestone until the solution contains 7.0% by weight S02, three-quarters of which is in the form of bisulfite ion. Why is this done In support of your answer to this question, calculate the pH of (a) the digestion solution prepared as above, (b) a hypothetical 7% solution of S02 alone, and (c) an actual saturated solution of S02 alone (2.9% S02), if the first acid dissociation constant of sulfurous acid is 1.7 x 10-2, at ambient temperature and pressure. 

Shao et al. recommended the use of a simultaneous fluorimetric method for the determination of the dissolution rate of dipyridamole and aspirin tablets [34]. The powdered tablets (equivalent to weight of one tablet) of dipyridamole and aspirin were dissolved in simulated digestive fluids at 37°C, cooled, and diluted to 1 L with simulated digestive juice. The solution was filtered, and a 1 mL portion of the filtrate was mixed with 0.1 M sodium hydroxide and then set aside at room temperature for 1 h. The solution was mixed with 8 mL of phosphoric acid buffer (pH 6.8) and fluorimetrically detected for dipyridamole at 493 nm (excitation at 418 nm). The coefficients of variation for within-day and within 5 days were 2% for both dipyridamole and aspirin. 

Bile, an acidic body fluid used in digestion, has a high concentration of hydronium ions. Predict its pH. 

Landry, F. Bazile, D. Spenlehauer, G. Veillard, M. Kreuter, J. Release of the fluorescent marker prodan from poly(D,L-lactic acid) nanoparticles coated with albumin or polyvinyl alcohol in model digestive fluids (USP XXII). J. Control. Release 1997, 44, 227-236. 

Those fata taken in with the food are unaltered by the digestive fluids, except in that they are freed from tiieir enclosing membranes in the stoniAcb, until they reach the duodenum here, under the influence of the pancreatic juice, the major port is converted into a fine emulsion, in which form it is absorbed by the ueteals. A smaller portion ia saponified, and the products of the saponification, free fatty acids, soaps, and glycerin. Sub uentiy absorbed ig lacteals and blood-vessels. 

Siu KWM and Berman SS (1983) Elimination of perchloric acid digestion of biological fluids for fluo-rometric determination of selenium. Anal Chem 55 1605-1606. 

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