Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Stearates”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed1992

Oily drug carriers in cancer chemotherapy. II. Preparation of viscous ethyl oleate for intraarterial infusion therapy and its disposition in rats and hamsters.

Viscous ethyl oleate (VEO) was prepared as an oil drug carrier by the addition of aluminum stearate or ethyl cellulose. Since the rate of shear of VEO containing aluminum stearate was greatly and nonlinearly changed against the shearing stress compared to that containing ethyl cellulose, the latter was used for subsequent microvascular and organ distribution experiments in rats and hamsters. For infusion into the carotid artery in hamsters, neat ethyl oleate (EO, 4cP) or VEOs of various apparent viscosities (40, 80, 120 cP-VEOs) embolized the vascular system in the cheek pouch, although arrival time to the site where the embolization was observed and the embolization period differed depending on the type of oily drug carrier. For infusion into the hepatic artery in rats, however, only 120 cP-VEO embolized the vascular system in the liver. After infusion of the oily drug carrier containing 3H-oleic acid into the artery of hamster cheek pouch and rat liver, 30-50% of the radioactivity was gradually eliminated within 48 h, whereas about 80% of the dose was rapidly eliminated after infusion to rat stomach and kidney. In addition, the amount of 120 cP-VEO remaining in each organ 48 h after infusion was higher than those of EO and 40 and 80 cP-VEOs. Histological observation after infusion in rat liver revealed that 120 cP-VEO slowly migrated from the artery or arteriole to the sinusoidal capillary region. These results suggest that 120 cP-VEO can be used as a drug carrier because of its function of vascular embolization and high retention in a targeted tissue.

Animals↗
PubMed2002

Studies of rapidly disintegrating tablets in the oral cavity using co-ground mixtures of mannitol with crospovidone.

We attempted the development of rapid oral disintegration tablets by direct compression using co-ground mixture of D-mannitol and crospovidone. The co-ground mixture was prepared with a vibration rod mill. The tablets were formed by compression using a single punch-tableting machine after addition of the co-ground mixture to non-ground D-mannitol, crospovidone and magnesium stearate. Regarding the properties of tablets, hardness and the time of disintegration were measured. The particle diameter and specific surface area of the co-ground mixture were measured. The tablets manufactured from a physical mixture of 30% (w/w) co-ground mixture of D-mannitol and crospovidone (mixed ratio 9 :1) with 65.5% (w/w) of non-ground mannitol, 4% (w/w) of crospovidone, and 0.5% (w/w) of magnesium stearate had good properties for rapidly disintegrating tablets in the oral cavity. They showed the hardness of 4.9 kg and disintegration time of 33 s. We found that adding co-ground mixture of D-mannitol and crospovidone is useful in enhancing hardness of the tablets that could not be achieved by addition of their individually ground mixture. The improvement in the hardness of the tablets was also observed when other saccharides and disintegrants were used. This method was proved to be applicable in the manufacture of tables of ascorbic acid, a water-soluble drug and nifedipine, a slightly water soluble drug; and the dissolution rate of nifedipine from the tablets in water was remarkably improved. The particle sizes of D-mannitol in the co-ground mixture were smaller than that of the individually ground mixture, resulting in a larger specific surface area of the co-ground mixture than that of the individually ground mixture. Therefore, it was presumed that crospovidone acted as a grinding assistant for D-mannitol in the co-grinding process, enhancing the hardness of tablets by increasing the contact area among powder particles.

Mannitol↗
PubMed2002

A case of rhinolithiasis in botswana: a mineralogical, microscopic and chemical study.

A case of rhinolithiasis in Southeast Botswana was treated and after removal in hospital, the rhinolith was subjected to macroscopic and microscopic examination, X-ray diffraction analysis, electron microscope analysis and partial botanical analysis. The rhinolith consists of a strongly elliptical core of calcium stearate (C36H70CaO4.H2O), surrounded by approximately 30 elongated concentric growth rings, consisting of sodium-containing whitlockite (Ca18Mg2(Na,H)(PO4)14). The different layers have various degrees of porosity and red staining, probably due to traces of amorphous iron oxide. The origin of the rhinolith started with a piece of plant material, lodged in the nose, which was replaced by calcium stearate, leaving some remnants of resistant epidermal plant tissue. During subsequent years, thin layers of whitlockite were deposited periodically around the core with the reddish brown bands representing deposition during the dry season when atmospheric dust rich in amorphous iron oxide is at its highest in Botswana.

Aged↗
PubMed2002

Purification and characterization of a novel cholesterol esterase from Pseudomonas aeruginosa, with its application to cleaning lipid-stained contact lenses.

With the aim of developing a new cholesterol esterase for eliminating lipids on used contact lenses, microorganisms were screened for the enzyme activity. A Pseudomonas aeruginosa isolated from soil was found to produce a desirable enzyme. The enzyme had an isoelectric point of 3.2, and molecular mass of 58 kDa. The optimal temperature was around 53 degrees C at pH 7.0, and the optimal pH was from 5.5 to 9.5. The enzyme was stable between pH 5 and 10 for 19 h at 25 degrees C, and retained its activity up to 53 degrees C on 30 min of incubation at pH 7.0. The rates of hydrolysis of cholesteryl esters of different fatty acids were in the following order: linoleate > oleate > stearate > palmitate > caprylate > myristate > laurate, caprate > caproate > butyrate, acetate. Addition of (tauro)cholate to a final concentration of 100 mM markedly promoted the hydrolysis of triglycerides of short-, medium-, and long-chain fatty acids. When used with taurocholate, the enzyme acted as an effective cleaner for contact lenses stained with lipids consisting of cholesteryl oleate, tripalmitin, and stearyl stearate.

Cholesterol Esters↗
PubMed2001

Manganese absorption and retention in rats is affected by the type of dietary fat.

There is evidence that manganese (Mn) metabolism may be altered by the form and amount of dietary fat. Also, iron (Fe) absorption is greater with saturated fats, as compared to polyunsaturated fatty acids (PUFAs). The absorption of Fe and Mn are interrelated in many aspects; therefore, the form of dietary fat may indirectly alter Mn absorption. The reported studies were conducted to determine whether saturated fat, as compared to unsaturated fat, affected Mn absorption, retention, and metabolism. In experiment I, adult rats were fed diets containing either 0.7 or 100.4 microg/g Mn with the fat source as high-linoleic safflower oil or stearic acid. After 2 wk of equilibration, the animals were fed a test meal of 54Mn followed by whole-body counting for 10 d. Manganese absorption was significantly (p < 0.05) lower in the stearic acid group (0.9-4.8%) than in the safflower oil group (20-33.8%); however, the biological half-life was shorter in the safflower oil group. Retention of 54Mn and total Mn was always significantly (p < 0.05) greater in the safflower oil group when dietary Mn was low, but it was the same when dietary Mn was high. In experiment II, weanling rats were fed 1.3, 39.3, or 174.6 microg Mn/g and either stearate, high-oleic safflower oil or high-linoleic safflower oil for 8 wk. Long-term feeding of the stearate and low Mn-containing diet resulted in a significant (p < 0.0001) reduction in heart superoxide dismutase activity and kidney and liver Mn concentrations compared to the other diets. These data show that stearic acid inhibitits Mn absorption, but it may not inhibit Mn retention when dietary Mn is high.

Animals↗
PubMed1989

Sensitive analysis of retinyl esters by isocratic adsorption chromatography.

A sensitive method for the determination of retinyl esters, including their geometric isomers, by isocratic adsorption HPLC is described. The development of a special recycling system allows the separation of all-trans-, 13-cis, 11-cis- and 9-cis-retinyl palmitate, -stearate, -oleate, -palmitoleate and -linoleate with short retention times and high sensitivity. Extraction of the retinyl esters from various organs with mobile phase avoids additional evaporation steps. The method was evaluated by the determination of retinyl esters in small tissue samples such as tongue, trachea and inner ear. This is the first report of the detection of retinyl esters in these tissues, which are known to depend on an adequate vitamin A supply. The main ester in all cases was retinyl palmitate, followed by retinyl stearate and oleate.

Animals↗
PubMed1985

Composition of cholesterol esters in blood plasma of mouse, rat and rabbit.

Mixtures of cholesterol estes were extracted from the blood plasma of mouse (C3H/He, C57BL/6J and Jcl : ICR), rat (Wistar) and rabbit (JW-NIBS/Rabiton) and purified by thin-layer chromatography. Fatty acid moieties of the esters were methylated with BF3-methanol and analyzed quantitatively by gas chromatography. Although linoleate was most abundant (over 30% of the total esters) and myristate was found only in traces, the composition of the esters varied markedly among the species. Mice had 15.3 to 17.4% of arachidonate, but only a trace of linolenate and no stearate. In rats, arachidonate and linoleate were found in almost equal quantities, but stearate, linolenate and docosahexaenoate were present in only trace amounts. Rabbits had more palmitate and oleate and less arachidonate and eicosapentaenoate than the other two animals, but no docosahexaenoate.

Animals↗
PubMed2003

What does the measurement of whole-body fatty acid rate of appearance in plasma by using a fatty acid tracer really mean?

We evaluated the validity of using a single fatty acid tracer to assess total plasma long-chain free fatty acid (FFA) kinetics and the relationship between the rate of appearance (R(a)) of fatty acids in plasma and the fatty acid composition of adipose tissue triglyceride (TG). A mixture of [(13)C]-labeled myristate, palmitate, stearate, oleate, and linoleate was infused in healthy men during basal conditions and during conditions that stimulate (epinephrine infusion) and inhibit (insulin infusion) lipolysis of adipose tissue TGs. Calculated total FFA, R(a) based on palmitate, oleate, or linoleate tracers, was within 15% of the measured sum of the individual fatty acid R(a) under all conditions, whereas stearate and myristate tracers consistently underestimated and overestimated total FFA R(a), respectively. The fatty acid R(a) profile closely matched the fatty acid profile of subcutaneous adipose tissue TGs during epinephrine infusion, but not during basal conditions and insulin infusion. Our data support the common practice of using labeled palmitate or oleate as fatty acid tracers for assessing total plasma FFA kinetics and suggest that a source of lipids other than adipose tissue TG release fatty acids into the systemic circulation.

Adipose Tissue↗
PubMed1998

Breed comparison of the fatty acid composition of muscle phospholipids in Jersey and Limousin cattle.

We investigated the fatty acid composition of the phospholipid fraction of the shoulder muscle (triceps brachii) from Jersey and Limousin yearling steers, yearling heifers, and nonlactating cows. The aim was to study breed, sex, and age differences. Significant breed differences in some individual fatty acids were apparent between Jersey and Limousin cows. Limousin cows had more palmitate, vaccenate, arachidonate, and less gamma-linolenate and eicosapentanoate than Jersey cows. Age differences were significant: proportions of palmitate, stearate, and oleate decreased and linoleate, arachidonate, and total polyunsaturates increased with age. Most of the breed x age interactions were not significant. Also, phospholipids of Jersey and Limousin cows did not differ in total saturated, monounsaturated, and polyunsaturated fatty acids. Yearling data revealed significant sex differences in most of the fatty acids, including total monounsaturates and polyunsaturates. Yearling steers had more myristate, palmitoleate, stearate, and total monounsaturates and less linoleate, arachidonate, eicosapentanoate, and total polyunsaturates than heifers. Breed differences were also significant: Limousin yearlings had more di-homogamma-linolenate and erucate and less eicosapentanoate and nervonate than their Jersey counterparts. The sex x breed interaction was not significant for most of the fatty acids. These results imply that breed, age, and sex are important factors that influence the fatty acid composition of muscle phospholipids in cattle.

Aging↗
PubMed1997

Economic analysis of treatment with roxithromycin in comparison with erythromycin in patients with lower respiratory tract infections.

A number of new antibiotics have lately become available for treatment of lower respiratory tract infections in out-patients. The new drugs are generally more expensive than the older ones, which might be justified by better effects, improved safety, or by other advantages. In this study, a retrospective economic analysis has been made using data from a previous trial comparing a new macrolide, roxithromycin, with an older 1, erythromycin stearate in the treatment of lower respiratory tract infections. The trial was multicentre, double blind, randomized and comparative. There were no significant differences in efficacy between treatments, although the cure rate was higher for roxithromycin, 85% vs 79% for erythromycin. 20/39 of the erythromycin-treated patients reported adverse events, vs 7/40 roxithromycin-treated subjects, a highly significant difference. More detailed information was obtained by reviewing the medical records of the participants, and from questionnaires distributed to the 3 centres that had included patients in the trial. Additional visits were found necessary for 4 patients treated with erythromycin and for 1 using roxithromycin. Using the healing rates in the present investigation, and including costs for initial drug treatments, second consultations, and failed therapy, average cost-effectiveness (SEK/patient cured) was 409 for roxithromycin-treated patients, and 488 for erythromycin-treated. Roxithromycin should then be cheaper than erythromycin stearate. With the same healing rate, roxithromycin would be less cost-effective, but indirect costs and effects on quality of life are not then taken into account.

Anti-Bacterial Agents↗
PubMedDate not supplied

Preparation and characteristics of microcapsules containing enoxacin by one continuous process of agglomeration and microencapsulation.

A novel microencapsulation technique was carried out with the phase separation of Eudragit RS from the wet spherical agglomeration (WSA) system by non-solvent addition. To elucidate the characteristics of microcapsules the spherical agglomerates containing enoxacin (ENX), lactose or Avicel which are different in their affinity to water (i.e. insoluble, soluble or absorbable properties, respectively), were prepared as core particles in an acetone/n-hexane mixture (volume ratio 3/7) by a WSA technique. The size of all kinds of spherical agglomerates was controlled by the amount of bridging liquid (ammonia water or distilled water) used. In the microencapsulation process encapsulation was performed efficiently at 400-600 rpm. Avicel agglomerates could be coated up to 30 per cent with Eudragit RS with less aggregation. Various additives were compared as additions into the system to avoid the aggregation of encapsulated particles. Addition of more than 3 per cent magnesium stearate based on the core weight in the system, before or at the same time as phase separation of Eudragit RS occurred, resulted in low aggregation of microcapsules for spherical agglomerates containing ENX or lactose. In formulating a water-absorbable excipient such as Avicel in the agglomerates of ENX, adding some 10 per cent Eudragit RS-dichloromethane solution into the WSA system, and using magnesium stearate as a protective agent, the resultant microcapsules could be obtained efficiently without aggregation, showing sustained release of ENX depending on coating level.

Acrylic Resins↗
PubMedDate not supplied

Stereospecific formulation and characterization of sustained release ibuprofen microspheres.

Ibuprofen microspheres were prepared from the racemate, (+)-S and (-)-R enantiomers using waxes such as ceresine and glyceryl stearate and stereospecifically characterized. The method of preparation of the microspheres was a hydrophobic congealable disperse phase encapsulation process and variables such as particle size, wax type, enantiomeric form were evaluated. Dissolution studies were carried out by a modified USP type II method and the samples were analysed by a stereospecific HPLC assay using S-(-)-1(1) naphthylethylamine as the derivatizing agent and fenoprofen as the internal standard. The mean particle sizes of (+)-S and (-)-R enantiomers determined by microscopy/image analysis were 64 and 99 microns respectively while that of the racemate was 48 microns. Differential Scanning Calorimetry (DSC) of ibuprofen and the enantiomers showed endothermic peaks at 72 and 55 degrees C respectively. Thermograms of the physical mixture and microspheres did not show the characteristic ibuprofen peak, indicating a change in crystallinity of the drug. Powder X-ray diffraction patterns of the enantiomers and racemic ibuprofen were found to be dissimilar indicating different crystal properties. The X-ray patterns for the microspheres did not show the characteristic peaks for the drug indicating that ibuprofen may be in solid solution with the waxes. Scanning electron micrographs of the microspheres showed a generally smooth and spongy appearance for the microspheres made of compritol and glyceryl stearate. Microspheres made from the paraffin waxes had rough and hard surface characteristics consistent with the higher melting point of the waxes. Ceresine microspheres made with the enantiomers had a rougher and more porous surface compared to the microspheres made with racemic ibuprofen. Stereospecific release of the recemate from the formulations was found to be sustained (T25 of 4 h), while release from the enantiomers was less sustained (T50 of 2 h). From the S:R ratios and statistical analysis of the data, the release of the enantiomers of ibuprofen from the formulations containing the racemate was found to be non-stereoselective.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1988

Vitamin A is stored as fatty acyl esters of retinol in the lacrimal gland.

Many tissues which require vitamin A store the vitamin as long-chain fatty acyl esters of retinol. As part of a study designed to characterize vitamin A metabolism in the lacrimal gland, which transports retinol from blood to lacrimal gland fluid, extracts from lacrimal glands of rabbits and rats were analyzed by non-aqueous high performance liquid chromatography. Retinyl linoleate, retinyl palmitate, and retinyl stearate were identified in these extracts by their co-elution with standards, their retention time relative to retinyl palmitate, and their susceptibility to hydrolysis by saponification. Retinyl palmitate was present in rabbit lacrimal gland at 51.0 +/- 10.1 ng/g tissue. After treatment of vitamin A-deficient rabbits with orally administered [11,12-3H] retinyl acetate, the radiolabeled esters retinyl linoleate, palmitate, and stearate were extracted from the lacrimal glands. These data show that the lacrimal gland stores vitamin A as fatty acyl esters of retinol.

Animals↗
PubMed1998

Thermal analysis as a screening technique in preformulation studies of picotamide solid dosage forms.

The potential compatibilities of several commonly used pharmaceutical excipients with picotamide were evaluated using differential scanning calorimetry (DSC). The effects of aging and of mechanical treatment (blending, grinding, or kneading) of samples were also evaluated. Hot-stage microscopy (HSM) and scanning electron microscopy (SEM) were used as complementary techniques to implement and assist in interpretation of the DSC results. DSC analysis evidenced a noticeable modification of drug thermal features in the mixtures with palmitic acid, stearic acid, stearyl alcohol, polyethylene glycol (PEG) 20,000, and sorbitol, but HSM analysis showed that the DSC behavior was mainly because of the drug dissolution in the melted excipient, which allowed the presence of important solid-solid interactions to be excluded. Compatibility with Mg stearate was also found, even if sample manipulation induced the partial conversion of Mg stearate in a pseudo-polymorphic modification. Mechanical stress displayed an increased hygroscopicity of mixtures with glucose and lactose, as well as some solid-solid interactions with lactose and mannitol.

Calorimetry, Differential Scanning↗
PubMed1989

Effects of E. coli 0111.B4 lipopolysaccharide on spin-labelled murine macrophage and hepatocyte membranes.

Macrophages and hepatocytes from normal and BCG-primed mice have been spin-labelled in their membranes with 5- and 16-doxyl stearic acid. Incubation of spin-labelled cells from BCG-primed animals with lipopolysaccharide from E. coli 0111.B4 produced a detectable and transient disturbance in the cell membranes as reflected by an increase in the order parameter measured from the electron spin resonance spectra of 5-doxyl-stearate. This membrane disturbance was maximal at 3-4 hours of incubation and was only detected with cells from mice primed with BCG. Spectra obtained from the 16-doxyl-stearate-labelled cells showed no change in order parameter on incubation with lipopolysaccharide.

Animals↗
PubMed1998

Identification of formulation and manufacturing variables that influence in vitro dissolution and in vivo bioavailability of propranolol hydrochloride tablets.

The purpose of this study was to evaluate the effect of formulation and processing changes on the dissolution and bioavailability of propranolol hydrochloride tablets. Directly compressed blends of 6 kg (20,000 units) were prepared by mixing in a 16-qt V blender and tablets were compressed on an instrumented Manesty D3B tablet press. A half-factorial (2(5-1), Resolution V) design was used to study the following variables: filler ratio (lactose/dicalcium phosphate), sodium starch glycolate level, magnesium stearate level, lubricant blend time, and compression force. The levels and ranges of the excipients and processing changes studied represented level 2 or greater changes as indicated by the Scale-up and Post Approval Changes (SUPAC-IR) Guidance. Changes in filler ratio, disintegrant level, and compression force were significant in affecting percent drug released (Q) in 5 min (Q5) and Q10. However, changes in magnesium stearate level and lubricant blend time did not influence Q5 and Q10. Hardness was found to be affected by changes in all of the variables studied. Some interaction effects between the variables studied were also found to be significant. To examine the impact of formulation and processing variables on in vivo absorption, three batches were selected for a bioavailability study based on their dissolution profiles. Thirteen subjects received four propranolol treatments (slow-, medium-, and fast-dissolving formulations and Inderal 80 mg) separated by 1 week washout according to a randomized crossover design. The formulations were found to be bioequivalent with respect to the log Cmax and log AUC0-infinity. The results of this study suggest that (i) bioavailability/bioequivalency studies may not be necessary for propranolol and perhaps other class 1 drugs after level 2 type changes, and (ii) in vitro dissolution tests may be used to show bioequivalence of propranolol formulations with processing or formulation changes within the specified level 2 ranges examined.

Adrenergic beta-Antagonists↗
PubMed1984

Roles of acetate and its interactions with glucose and lactate in cow mammary tissue.

Slices from mammary glands from six lactating Holstein cows were incubated in Krebs-Ringer bicarbonate-based media in the presence of varying concentrations of acetate, glucose, and lactate. Conversions of acetate to carbon dioxide, fatty acids, citrate, glyceride-glycerol, and lactose were determined. Specific effects of beta-hydroxybutyrate and stearate availability also were evaluated. Utilization of acetate for all functions usually followed Michaelis-Menten kinetics with apparent affinities in the physiological concentration range of acetate. Availability of glucose had a large "permissive" effect on acetate to conversion to fatty acids. However, acetate metabolism was independent of the availability of lactate. Conversion of acetate to glyceride-glycerol was significant. This indicates the possibility of bidirectional glycolytic flux, which could limit glucose conversion to fatty acids. Addition of stearate caused general increases of acetate metabolism. Conversion of acetate to fatty acids, carbon dioxide, and citrate was elevated in the absence of beta-hydroxybutyrate. The latter observation indicates beta-hydroxybutyrate may not be a required initiator of fatty acid synthesis in mammary tissue.

Acetates↗
PubMed1989

In vitro degradation of choline from selected feedstuffs and choline supplements.

The objective of this experiment was to determine the extent of in vitro degradation of choline from barley, corn, corn gluten meal, cottonseed meal, fish meal, soybean meal, alfalfa hay, timothy hay, choline chloride, and choline stearate. During four individual fermentation runs, samples were incubated in vitro for .25, 1, 3, 6, 12, 18, 24, 36, and 48 h with an inoculum mixture containing rumen fluid obtained from a rumen-fistulated dairy cow fed 17.5% corn silage and 28.7% grass silage and 53.8% concentrate diet. Because of their low choline content (less than .68 mg/g) corn, corn gluten meal, alfalfa hay, and timothy hay gave erratic values for choline disappearance for different fermentation runs and times of incubation although disappearance tended to increase with time. Data for the rest of the feeds and choline supplements were analyzed using nonlinear regression procedure to obtain estimates of potentially degradable choline, rapidly degradable choline, and the rate of choline degradation in vitro. The mean estimates of rumen degradable choline (%) were 79.4, 84.7, 82.9, 83.8, 98.0, and 98.6 for barley, cottonseed meal, fish meal, soybean meal, choline stearate, and choline chloride, respectively. The results suggest that incorporating choline-rich feedstuffs in diets can only marginally increase the postruminal flow of choline in dairy cows.

Animal Feed↗