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Biomedical subjects

J R Schultz

Publications and source records attributed to J R Schultz.

52 records · Page 3Linked to original sources
PubMed1976

Effects of colestipol hydrochloride on drug absorption in the rat II.

The effects of colestipol hydrochloride, a hypocholesterolemic bile acid-binding anion-exchange polymer, on the GI absorption of drugs commonly used in humans were studied in the rat. Colestipol hydrochloride was given by gavage in single doses of 71.5 or 214.5 mg/kg, equivalent to 5 or 15 g, respectively, in a 70-kg human; controls received equivalent amounts of microcrystalline cellulose. Single oral doses of labeled drugs were given concurrently with colestipol hydrochloride or microcrystalline cellulose at the human therapeutic dose range on a milligrams per kilogram basis. Subsequent changes in serum drug levels were measured at several time periods, and absorption was evaluated as the total area under the time-concentration curve. Colestipol hydrochloride at either dose did not significantly alter the absorption of 6-14C-nicotinic acid, 7-3H-tetracycline, 35S-chlorpromazine, 12alpha-3H-digoxin, warfarin (alpha-14C-benzyl), or clofibrate (14C-carboxyl). In addition, the effects of 214.5 mg/kg of colestipol hydrochloride were compared with the same dose of cholestyramine with respect to the absorption of 3-14C-hydrochlorothiazide, 2-14C-phenobarbital, and 3H-digitoxin. Cholestyramine reduced absorption of hydrochlorothiazide by 42%, but colestipol hydrochloride had no significant effect. Neither resin altered phenobarbital or digitoxin absorption when compared with the the control, but a significant difference occurred between the two resins with digitoxin; areas under the time-concentration curve [in (dpm/0.1 ml serum) x hr] were: colestipol hydrochloride, 2001; cholestyramine, 16,300; and cellulose, 17, 067. These results indicate that colestipol hydrochloride and cholestyramine can differ in their effects on the absorption of certain drugs from the GI tract of the rat.

Animals↗
PubMed1976

High volume screening procedures for hypobetalipoproteinemic activity in rats.

We describe high volume screening tests for hypobetalipoproteinemic agents in which compounds are administered orally to cholesterol-cholic acid fed (hypercholesterolemic( or normally fed weanling rats for 4 days. In these tests total serum cholesterol levels and heparin precipitating lipoproteins (HPL) are determined by automated analyses interfaced with a computer which eliminates all manual data reduction and provides necessary reports. The hypercholesterolemic rat test detects compounds which specifically reduce HPL (beta and pre beta lipoproteins) causing a decrease in the HPL: cholesterol ratio. Such activity is called hypobetalipoproteinemia. This activity is exhibited by bicyclo (2.2.2)-octyloxyaniline (U-26328) but not by any of the familiar hypocholesterolemic agents including clofibrats, lifibrats, nicotinic acid, probucol, triparanol, lentysine, D-throxine or the estrogens estrone and diethylstilbestrol.

Analog-Digital Conversion↗
PubMed1976

Gastric antisecretory and antiulcer properties of PGE2, 15-methyl PGE2, and 16, 16-dimethyl PGE2. Intravenous, oral and intrajejunal administration.

15-Methyl PGE2 and 16,16-dimethyl PGE2 were found (1) to be 40 and 100 times, respectively, more potent than PGE2 after intravenous administration in inhibiting histamine-stimulated gastric secretion in dogs with a denervated (Heidenhain) gastric pouch, (2) to be active orally and intrajejunally, whereas PGE2 was inactive, and (3) to exert antisecretory activity for longer duration than PGE2. 16,16-Dimethyl PGE2 was about 2.5 times more potent than 15-methyl PGE2. Volume, acid concentration, and output, and pepsin output (but not concentration) were reduced in a dose-dependent manner. In the rat, 16,16-dimethyl PGE2 also inhibited gastric secretion and prevented the formation of ulcers produced by various methods: gastric ulcers (Shay, and steroid induced) and duodenal ulcers (secretogogue induced). In this species, 1l816-dimethyl PGE2 was 2 to 50 times more potent than PGE2, depending on the endpoint, and was active orally. These prostaglandins appear to inhibit gastric acid secretion by acting directly on the parietal cells, and making these unresponsive to most stimulants. Vomiting was a side effect of the prostaglandin analogues in the dog, but almost exclusively when these were given orally. After intravenous or intrajejunal administration at doses inhibiting gastric secretion by 80%, vomiting was seen only once. These results suggest that 15-methyl PGE2 and 16,16-dimethyl PGE2 may be of value in the treatment of peptic ulcer.

Administration, Oral↗
PubMed1975

Urinary proteins in Sprague-Dawley rats with chronic progressive nephrosis.

By means of polyacrylamide concentration and electrophoresis on cellulose acetate strips, protein fractions have been determined in the urine of male Sprague-Dawley rats from 6 1/2-28 mo of age. An increasing percentage of albumin was expressed in the albumin/globulin ratios of 0.72, in a group of rats excreting a mean concentration of 1.91 mg/ml of protein in the urine, and 2.24 in a group of rats excreting, on the average, 17.62 mg/ml. A relative decrease in globulin, particularly of the alpha2 fraction, was shown. From a statistical model based on the regression parameters for 24-hr protein excretion and urine protein concentration, it was estimated that the doubling time for protein excretion was 3.2-3.69 mo. This interval is roughly one-half that reported for the Wistar rat.

Albuminuria↗