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PubMed1976

[Blood concentration and urinary excretion in human of OE-7, a gastric hard capsule containing enteric-coated granules. I (author's transl)].

The investigation of physico-chemical properties and measurement of blood concentration and amount of excretion into urine in human of OE-7 (main constituent is erythromycin stearate) were performed as the fundamental studies. The results obtained were as follows; i) OE-7 is a gastric hard capsule containing enteric coated granules. ii) The contents of OE-7 capsule (granules) were resistant to acid and was favarable in the enteric solubility. iii) In comparison with the conventional erythromycin stearate capsule in healthy adults, OE-7 showed a relatively small individual difference in blood concentration after administration. iv) OE-7 was higher in the mean blood concentration and was superior in the persistence of effective blood concentration compared with the conventional erythromycin stearate capsules.

Adult↗

PubMed2003

[Compressibility of directly compressed forms of lactitol].

Lactitol ranks among sugar alcohols which are employed as dry binders in the manufacture of tablets, particularly the chewable ones. Water-granulated lactitol is the directly compacting form of this substance. The present paper studies the compressibility of the granulated form of lactitol and the effects of different concentrations of the lubricant magnesium stearate on the strength and disintegration time of the compacts from his substance. Lactitol cannot be compressed without an added lubricant. Magnesium stearate, employed in two concentrations, 0.4% and 0.8%, did not negatively interfere with the strength of the compacts. The disintegration period of tablets was prolonged with increasing stearate concentration, but independently of compression force.

Chemistry, Pharmaceutical↗

PubMed1992

Hydrogenation alternatives: effects of trans fatty acids and stearic acid versus linoleic acid on serum lipids and lipoproteins in humans.

The objective of this study was to compare the effects of linoleic acid (cis,cis-C18:2(n-6)) and its hydrogenation products elaidic (trans-C18:1(n-9)) and stearic acid (C18:0) on serum lipoprotein levels in humans. Twenty-six men and 30 women, all normolipemic and apparently healthy, completed the trial. Three experimental diets were supplied to every subject for 3 weeks each, in random order (multiple cross-over). The Linoleate-diet provided 12.0% of total energy intake as linoleic acid, 2.8% as stearic acid, and 0.1% as trans fatty acids. The Stearate-diet supplied 3.9 energy % as linoleic acid, 11.8% stearic acid, and 0.3% trans fatty acids. The Trans-diet provided 3.8 energy % as linoleic acid, 3.0% stearic acid, and 7.7% as monounsaturated trans fatty acids, largely elaidic acid (trans-C18:1(n-9)). Other nutrients were constant. Fasting blood was sampled at the end of each dietary period. Mean (+/- SD) serum LDL cholesterol was 109 +/- 24 mg/dl (2.83 +/- 0.63 mmol/l) on the Linoleate-diet. It rose to 116 +/- 27 mg/dl (3.00 +/- 0.71 mmol/l) on the Stearate-diet (change, 7 mg/dl or 0.17 mmol/l, P = 0.0008) and to 119 +/- 25 mg/dl (3.07 +/- 0.65 mmol/l) on the Trans-diet (change, 9 mg/dl or 0.24 mmol/l, P less than 0.0001). High density lipoprotein (HDL) cholesterol decreased by 2 mg/dl (0.06 mmol/l, P less than 0.0001) on the Stearate-diet and by 4 mg/dl (0.10 mmol/l, P less than 0.0001) on the Trans-diet, both relative to linoleic acid. Our findings show that 7.7% of energy (mean, 24 g/day) of trans fatty acids in the diet significantly lowered HDL cholesterol and raised LDL cholesterol relative to linoleic acid. Combination with earlier results (Mensink, R. P., and M. B. Katan. 1990. N. Engl. J. Med. 323: 439-445) suggests a linear dose-response relation. Replacement of linoleic acid by stearic acid also caused somewhat lower HDL cholesterol and higher LDL cholesterol levels. Hydrogenation of linoleic acid to either stearic or trans fatty acids produces fatty acids that may increase LDL and decrease HDL cholesterol relative to linoleic acid itself.

Adolescent↗

PubMed2006

[A study of the properties of tablets from mixtures of two size degrees of alpha-lactose monohydrate and microcrystalline cellulose].

The paper examines the strength and disintegration time of compacts from the mixtures of two types of Tablettosas. Tablettosa 70 and Tablettosa 100 with microcrystalline cellulose represented by Vivapur 102. The mixtures of dry binders were prepared in the ratios of 3:1, 1:1, and 1:3. The effect of two concentrations of the lubricant magnesium stearate on the strength and disintegration time of compacts was also examined. Tablet strength increased with higher representation of microcrystalline cellulose in the mixture, and decreased with higher stearate concentration. The compacts from the mixtures with Tablettosa 100 showed higher strength. Disintegration time was highest in the compacts with the largest perccintage of microcrystalline cellulose, and longer in the case of the mixtures with Tablettosa 100. Stearate did not exert a negative effect on disintegration time. In the mixtures of Tablettosas with Vivapur 102 in a ratio of 1:1, the effect of the model active ingredient acetylsalicylic acid on the above-mentioned properties of tablets was tested. acetylsalicylic acid produced a further decrease in the strength of compacts and shortened the disintegration time in more instances in the cased of the mixtures with Tahlettosa 100.

Aspirin↗

PubMed2006

Rumen ciliate protozoa contain high concentrations of conjugated linoleic acids and vaccenic acid, yet do not hydrogenate linoleic acid or desaturate stearic acid.

Conjugated linoleic acids (CLA) have been shown to improve human health. They are derived from the microbial conversion of dietary linoleic acid (cis-9,cis-12-18 : 2 (LA)) in the rumen. An investigation was undertaken to determine the role of ruminal ciliate protozoa v. bacteria in the formation of CLA and its precursor in animal tissues, vaccenic acid (trans-11-18 : 1 (VA)). Mixed protozoa from the sheep rumen contained at least two to three times more unsaturated fatty acids, including CLA and VA, than bacteria. Different species had different composition, with larger fibrolytic species such as Epidinium ecaudatum caudatum containing more than ten times more CLA and VA than some small species, including Entodinium nanellum. In incubations with ruminal microbial fractions (bacterial fraction (BAC), protozoal fraction (PRO)), LA metabolism was very similar in strained ruminal fluid (SRF) and in the BAC, while the PRO had LA-metabolising activity an order of magnitude lower. Using PCR-based methods, no genes homologous to fatty acid desaturase genes were found in cDNA libraries from ruminal protozoa. The absence of an alternative route of VA/CLA formation via desaturation of stearate was confirmed by incubations of SRF, BAC or PRO with [14C]stearate. Thus, although protozoa are rich in CLA and VA, they appear to lack the ability to form these two fatty acids from LA or stearate. The most likely explanation is that protozoa preferentially incorporate CLA and VA formed by bacteria. The implication of the present findings is that the flow of unsaturated fatty acids, including CLA and VA, from the rumen could depend on the flow of protozoa rather than bacteria.

Animals↗

PubMed1978

The binding isotherms for the interaction of 5-doxyl stearic acid with bovine and human albumin.

Binding isotherms for the interaction of 5-doxyl stearic acid with bovine and human albumin are reported. The critical micelle concentration (CMC) and the limiting solubility of 5-doxyl stearic acid were determined using the electron spin resonance (ESR)-spin label method. The CMC and the limiting solubility of this spin-label stearic acid in saline-phosphate buffer are 3.5 x 10(-5) M and 2 x 10(-4) M, respectively. We found no ESR line width evidence for pre-association of the spin-label stearate below the CMC. Maximum binding of the spin-label stearate to both bovine and human albumin occurs before micelle formation. The binding isotherm for spin-label stearic acid interaction with bovine albumin is in agreement with data obtained by others using [1-(14)C]stearic acid. For human albumin, comparison is difficult since previous data obtained with [1-(14)C]stearic acid vary widely. Comparison of the ESR 2T(||) values (the splitting between low and high field extremes, a measure of the degree of immobilization of protein-bound spin-label stearate) for bovine and human albumin indicates a greater immobilization of the spin-label molecules bound to human albumin. The binding data indicate that complexes are formed with bound spin-label stearate/albumin ratios of at least 18. The computed equilibrium constants for both bovine and human albumin indicate that the first seven spin-label molecules are tightly bound, log K > 5.0. The species predicted to form in solution by these equilibrium constants are reported.

Electron Spin Resonance Spectroscopy↗

PubMed1988

Apolipoprotein B synthesized by Hep G2 cells undergoes fatty acid acylation.

Apolipoprotein B is the principal protein associated with cholesterol transport in the blood and has been proposed to play a central role in human atherogenesis. The unique hydrophobic nature of this large (512 kDa), glycosylated apolipoprotein differs from that of the other apolipoproteins. Since another apolipoprotein, apolipoprotein A-I, has been recently shown to have covalently bound fatty acids, potential fatty acid acylation of apolipoprotein B was investigated. The human hepatoma cell line, Hep G2, synthesizes apoB-100 and secretes the apolipoprotein into the culture medium. After a 24-hr incubation with [14C]palmitate and [14C]stearate, the label was incorporated into apoB-100 when assessed by a sodium dodecyl sulfate polyacrylamide gel electrophoresis, autoradiography, immunoblot analysis, and immunoprecipitation. Hydroxylamine treatment, which hydrolyzes ester and thioester bonds, removed the radiolabel. ApoB-100 isolated from Hep G2 cells by ultracentrifugation and preparative sodium dodecyl sulfate gel electrophoresis was hydrolyzed and analyzed by gas-liquid chromatography-mass spectrometry. In contrast to circulating apoB in low density lipoproteins, both palmitate and stearate were present in newly synthesized apoB-100. These results establish that newly synthesized apoB-100 undergoes covalent acylation with palmitate and stearate. The acylation of apoB may play an important role in lipoprotein particle secretion. In addition, derangements in apoB fatty acid acylation may lead to dyslipoproteinemia.

Acylation↗

PubMed1988

Toxicity and character of the effect of some zinc compounds.

Investigation of the parameters of toxicity of 8 zinc compounds revealed some differences in the degree of their risk for persons working with them. The following TSELs (tentative safe exposure levels of harmful substances) have been determined: 0.5 mg/m3 for zinc nitrate and hydrogen and dihydrogen zinc phosphates, 2 mg/m3 for zinc carbonate and zinc selenide, as well as MAC (maximum allowable concentration) for zinc sulphide equal to 5 mg/m3. No TSEL have been set for zinc caprylate and zinc stearate, but intratracheal administration of 50 mg caprylate caused 100%, of stearate 50% death of experimental animals due to pulmonary edema. Maximum tolerable doses were 10 and 1 mg, respectively. Zinc nitrate shows an expressed irritative effect on the skin and a highly expressed effect on the conjunctiva. Zinc phosphates, zinc caprylate and zinc stearate are resorbed by the skin. In all cases, working persons must be protected from the effect of the compounds under study because even though the toxicity of a compound may be rather low, highly noxious compounds may develop in the course of the technological process, e.g., in mechanical treatment of zinc selenide and zinc sulphide monocrystals, hydrogen selenide and hydrogen sulphide, respectively, can be isolated.

Administration, Cutaneous↗

PubMed1987

Fatty acid modification of C3H 10T 1/2 fibroblast cells: changes in benzo(a)pyrene metabolism and phorbol ester binding.

The mouse embryo fibroblast cell line, C3H 10T 1/2 Cl8, was studied as an in vitro experimental model to investigate the mechanism and specificity behind the modulation of carcinogenesis by dietary lipid. The cells were grown in medium supplemented with 95 microM stearate, linoleate, or palmitate as fatty acid/albumin complexes, during which time they maintained normal growth and morphology characteristics. After 5 days of supplementation total cellular lipid fatty acid was enriched in the supplemented fatty acid. By Day 40, however, fatty acid profiles of all groups were the same. Cellular uptake and utilization of 14C-radiolabeled fatty acids were measured. Within 24 h of supplementation, label was incorporated into cholesterol and diglycerides, cholesterol ester, alkyldiacylglycerols, and phospholipids. Approximately half of the radiolabel was found in phosphatidylcholine. Supplementation significantly increased the rate of benzo(a)pyrene metabolism, but did not affect DNA modification by benzo(a)pyrene. Phorbol dibutyrate binding to C3H 10T 1/2 cells at 4 degrees C was modified by lipid supplementation. At 37 degrees C and 23 degrees C, phorbol dibutyrate binding was characterized by both high- and low-affinity sites for linoleate- and stearate-supplemented cells. At 4 degrees C high-affinity binding was absent in stearate- and palmitate-supplemented cells, but was maintained in linoleate-supplemented cells. These studies suggest that the unsaturated fatty acid content of the diet may not significantly affect the initiation stage of benzo(a)pyrene carcinogenesis, but may instead affect promotion. One possible mechanism for this could involve changes in the lipid microenvironment of membrane receptors involved in tumor promotion.

Animals↗

PubMed1978

Bioavailability and effect of food on the gastrointestinal absorption of two erythromycin derivatives.

The concentrations of erythromycin in the serum were comparable after a single 500 mg oral dose of two brands of erythromycin stearate (Resibion and Erythrocin) in six healthy fasting volunteers. There was no significant difference in their pharmacokinetics. Over a period of 24 hours, 4 and 5% of the 500 mg dose of each preparations was excreted in the urine. Analysis of serum erythromycin concentration data were performed according to a one-compartment open model. The short half-life in the serum (1.43-1.78 hours), small portion of the dose excreted in the urine (4-5%), and the low renal clearance value (0.43-0.51 ml/min/kg) indicate that the majority of erythromycin is extensively cleared by extrarenal mechanisms. In addition, serum concentrations of erythromycin were measured during continuous treatment (250 mg base every 6th hour) with erythromycin stearate (Resibion) or enteric-coated erythromycin base (Etromycin) in ten healthy volunteers, in both fasting and non-fasting conditions. Again in the fasting state the serum levels were comparable and those from both the stearate and base were markedly reduced by food.

Administration, Oral↗

PubMed1972

Effect of ionization and cation selectivity on the expansion of stearic acid monolayers.

Force-area isotherms of stearic acid and stearic acid-stearyl alcohol mixtures were investigated on alkaline subphases that contained Tris, Na(+), or K(+) cations and that varied in pH and ionic strength. The monolayer behaved as though ionization was effectively complete in the expanded region of the force-area isotherm. Surface pressure in this region was independent of pH and varied inversely with ionic strength as predicted by the Davies equation. The monolayer behaved as a partially ionized film in the plateau region of the force-area isotherm. Surface pressure in this region varied directly with pH and ionic strength as predicted by a modified Davies equation for partially ionized monolayers. The neutral molecule, stearyl alcohol, exerted a large condensing effect on the ionized film at pH 12.8, and this condensing effect also supported the concept that a partially ionized stearic acid film existed in the plateau region of the force-area isotherm. A greater binding affinity for Na(+) than for K(+) showed that the stearate anion surface behaved as a strong field at pH 10 and above, and a greater binding affinity for K(+) than for Na(+) showed that the stearate anion surface behaved as a weak field at pH 9. The weak field explained in part the anomalous binding affinity of the large Tris cation for the stearate monolayer at pH 9.

Buffers↗

PubMed1984

Plasma kinetics of oral retinol in cancer patients.

Concurrent with a phase I trial of retinol in patients with advanced cancer, we studied the plasma kinetics of both retinol and its major metabolites, retinyl palmitate and retinyl stearate. Retinol was administered to 12 patients in daily oral doses of 60,000, 100,000, 150,000, or 200,000 units/m2. Patients remained on treatment until the development of dose-limiting toxic effects or disease progression. Retinoid plasma kinetics were studied on the first day of treatment, at Weeks 2 and 4, and every 2-3 months thereafter as long as the patient remained on therapy. A high-performance liquid chromatography assay was used to quantitate the plasma concentration of both retinol and its fatty acid esters. There was no significant change in the plasma retinol concentration up to 24 hours after a single oral dose of retinol (P greater than 0.05). However, the plasma concentration of retinyl palmitate and retinyl stearate markedly increased with a mean time to peak plasma concentration of 4.3 +/- 0.7 hours. Retinyl palmitate rapidly disappeared from the plasma with an initial phase half-life of 2.2 +/- 0.9 hours. The terminal phase half-life appeared prolonged and could not be accurately determined. Retinyl stearate was detected in the plasma of all patients with plasma concentrations paralleling and ranging from 20% to 40% those of retinyl palmitate. With prolonged retinol administration, peak plasma retinyl palmitate concentrations increased with both increasing retinol dose (P less than 0.001) and increasing duration of treatment (P = 0.001). In three patients with low pretreatment plasma retinol concentrations, daily retinol administration was associated with a rise in plasma retinol concentration. Because only one patient developed serious toxic effects and all patients had markedly increased plasma concentrations of retinyl esters, no conclusion could be made about the relationship between plasma retinyl ester concentration and retinol toxicity.

Administration, Oral↗

PubMed1983

[Content, intensity of exchange, and metabolic interaction of phospholipids and glycolipids in various tissues in experimental diabetes].

The contents of individual gangliosides in various tissues (e. g. heart, skeletal muscles, liver, brain, kidney, spleen, pancreas) under normal conditions and in alloxan diabetes as well as the incorporation of 1-14C-stearate into the phospholipid, glyceride and total ganglioside fractions were studied. The oxidation of 14C-fatty acid and the activities of neuraminidase and lipase in these tissues were determined. It was found that diabetes is concomitant with a marked decrease of the content and exchange of gangliosides, which is paralleled with activation of neuraminidase. The incorporation of 14C-stearate in the sphingomyelin and phosphatidylcholine fractions is significantly decreased, while that in the cardiolipin fraction is increased 1.5 - 2-fold. The oxidation of 14C-stearate is also increased, the degree of this increase being tissue-specific.

Adrenal Glands↗

PubMed1983

Vitamin A utilization in human retinal pigment epithelial cells in vitro.

Vitamin A (vit A) metabolism was studied in freshly isolated and cultured human retinal pigment epithelial (RPE) cells obtained from postmortem donor eyes. Fluorometric determination of vit A in human RPE cells demonstrated that freshly isolated cells contained approximately 1.0 to 4.0 pg vit A/cell which decreased with increasing time in culture; after 48 hrs in culture cellular vit A was reduced 80%. High performance liquid chromatography (hplc) profiles of the retinyl esters in freshly isolated RPE cells showed the presence of 11-cis retinyl stearate and palmitate and all-trans retinyl stearate, palmitate and oleate; all-trans palmitate was the major ester. Hplc analyses of cell cultures supplemented with all-trans retinol, using fatty acid-free bovine serum albumin as a carrier, showed that the cells in primary and subcultures took up all-trans retinol and esterified it to form palmitate, stearate, and oleate. Palmitate was the major ester synthesized by the cells in primary cultures. In the subcultures the esters synthesized differed from that found in freshly isolated cells and in the cells in primary culture; in the subcultures, the overall synthesis of ester was reduced and oleate was more prominent. The esters that were synthesized in culture were all-trans; the formation of 11-cis isomers was not observed in human RPE cells in culture. Electron microscopy of retinol-supplemented cultures indicated that vit A doses up to 1.0 micrograms/ml had no obvious effects on the cells; at higher doses the cells no longer adhered to the culture surface.

Cells, Cultured↗

PubMed1975

Application of powder failure testing equipment in assessing effect on glidants on flowability of cohesive pharmaceutical powders.

Powder failure testing equipment was used successfully to study the effect of glidants on the flowability of two cohesive pharmaceutical powders, lactose and calcium hydrogen phosphate, using the flow factor as the flowability parameter. Fine silica, magnesium stearate, and purified talc were investigated as glidants; for each host powder-glidant mixture, an optimum concentration of glidant was observed beyond which no further increase in flowability occurred. The order of efficiency of glidants for both host powders was fine silica greater than magnesium stearate greater than purified talc. The mode of action of the three glidants is discussed.

Calcium Phosphates↗

PubMed1976

Comparative evaluation of tablet lubricants: effect of application method on tablet hardness and ejectability after compression.

The effect of four lubricants (stearic acid, magnesium stearate, calcium stearate, and talc) on the ejectability and hardness of statically compressed tablets of a lactose granulation was examined. Two methods of application of these lubricants, incorporation into the granulation and mixing with the granulation, were compared. In both methods, the energy consumption curves during ejection and the hardness curves with lubricant concentration were similar and showed complicated behavior at a lower concentration. The mixing method gave better results for ejectability and hardness than the incorporation method.

Drug Compounding↗

PubMed1981

Physicochemical properties of magnesium salicylate.

Magnesium salicylate tetrahydrate is a nonhygroscopic, crystalline powder, whereas anhydrous magnesium salicylate is amorphous and very hygroscopic. Magnesium salicylate tetrahydrate tablets formulated with gelatin as a binder showed a dissolution half-life (t1/2) of 12 min, whereas a formulation using pregelatinized starch as a binder showed a t1/2 of 33 min. The optimum level of calcium stearate in the formulation was determined by the oscilloscope tracings of compressional and ejectional forces from an instrumented rotary tableting machine. Increasing the level of calcium stearate from 1 to 1.5 and 2% resulted in dissolution t1/2 values of 12, 18, and 21 min, respectively, and a higher incidence of softer tablets and capping.

Chemistry, Pharmaceutical↗

PubMed2006

Percolative transport and cluster diffusion near and below the percolation threshold of a porous polymeric matrix.

PURPOSE: The purpose of this research was to develop a quantitative mass transport model to describe the release of a drug from a porous inert matrix dosage form near and below the percolation threshold for the system. METHODS: Cumulative release profiles were generated for a series of tablets composed of a binary mixture of varying amounts of non-conducting (poly(vinyl stearate)) and conducting (benzoic acid) components. The porous microstructure was analyzed using re-constructed three-dimensional images of leached microtomed tablet sections. Poly(vinyl stearate) was characterized for transport properties, molecular weight and thermal properties. RESULTS: Based on percolation theory, the binary matrix was determined to have a percolation threshold of 0.09 +/- 0.02. Transport, which could not be explained by "classical" percolation theory or surface diffusion alone, was observed below the percolation threshold for the system. CONCLUSIONS: A model describing transport near and below the percolation threshold in matrices composed of two phases, polymer and drug, was developed. The percolation model developed accounts for diffusion within the porous structure and through the inert, insoluble polymeric amorphous regions of the matrix. The low percolation threshold and subsequently high coordination was concluded to be due to the biphasic classical porous and nonclassical polymeric diffusional transport mechanisms associated with the system studied.

Algorithms↗