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At least 19 recordsLinked to original sources

PubMed1989

Efficacy of erythromycin acistrate (2'-acetyl erythromycin stearate) and erythromycin stearate in experimental infections in mice.

The efficacy of erythromycin stearate (ES) and its 2'-acetyl ester (erythromycin acistrate, EA) was compared in eight experimental infections in mice of both sexes. In two studies the mice were made leukopenic by whole-body irradiation. Four absorption studies were also performed in parallel. In Streptococcus pneumoniae peritonitis, the protective dose 50% (PD50) value of EA and ES, given s.c., did not differ from each other. The bioavailability of EA was slightly inferior to that of ES. In three other peritonitis studies (2 Staphylococci and 1 Streptococcus), where the treatments were given s.c., EA seemed to lag behind ES in efficacy. The parallel absorption experiment showed, however, that, as compared to ES, only about one-half of EA was released from the s.c. injection site to the blood. The adjusted PD50 values of both erythromycins were about the same, with one exception. When the treatments were given i.p. both erythromycins were equally effective, and the difference in bioavailability was minor. On the contrary, the efficacy of 2'-ethylsuccinyl erythromycin was only about one-tenth that of the other erythromycins as was also the bioavailability. Oral treatment gave similar therapeutic results with EA and ES, with similar bioavailabilities, too. In the muscle abscess model, single s.c. injections of EA and ES were equally effective in reducing the growth of Staphylococcus aureus. These results suggest that there is no great difference in the in vivo antibacterial performance of ES and its 2'-acetyl ester, although the absorption problems complicate the interpretation. Hence EA performs better than expected if only the hydrolyzed drug were useful.

Animals↗

PubMed1976

Anthroyl stearate as a fluorescent probe of chloroplast membranes.

1. A reversible light-induced enhancement of the fluorescence of a "hydrophobic fluorophore", 12-(9-anthroyl)-stearic acid (anthroyl stearate), is observed with chloroplasts supporting phenazine methosulfate, cyclic or 1,1'-ethylene-2,2'-dipyridylium dibromide (Diquat) pseudo-cyclic electron flow; no fluorescence change is observed when methyl viologen or ferricyanide are used as electron acceptors. The stearic acid moiety of anthroyl stearate is important for its localization and fluorescence response in the thylakoid membrane, since structural analogs of anthroyl stearate lacking this group do not show the same response. 2. This effect is decreased under phosphorylating conditions (presence of ADP, Pi, Mg2+), and completely inhibited by the uncoupler of phosphorylation NH4Cl(5-10mM), as well as the ionophores nigericin and gramicidin-D (both at 5 - 10(-8)M). The MgCl2 concentration dependence of the anthroyl stearate enhancement effect is identical to that previously observed for cyclic photophosphorylation, as well as for the formation of a "high energy intermediate". The anthroyl stearate fluorescence enhancement is inhibited by increasing concentrations of ionophores in parallel with the decrease in ATP synthesis, but is essentially unaffected by specific inhibitors (Dio-9 and phlorizin) of photophosphorylation; thus, it appears that anthroyl stearate monitors a component of the "high energy state" of the thylakoid membrane rather than a terminal phosphorylation step. 3. The light-induced anthroyl stearate fluorescence enhancement is suggested to monitor a proton gradient in the energized chloroplast because (a) similar enhancement can be produced by sudden injection of hydrogen ions in a solution of anthroyl stearate; (b) when the proton gradient is dissipated by gramicidin or nigericin light-induced anthroyl stearate fllorescence is eliminated; (c) when the proton gradient is dissipated by tetraphenylboron, light-induced anthroyl stearate fluorescence decreases, and (d) light-induced anthroyl stearate fluorescence change as a function of pH is qualitatively similar to that observed with other probes for a proton gradient (e.g. 9-aminoacridine). Furthermore, anthroyl stearate does not monitor H+ uptake per se because (a) the pH dependence of H+ transport is different from that of the anthroyl stearate fluorescence change, and (b) tetraphenylboron, which does not inhibit H+ uptake, reduces anthroyl stearate fluorescence. Thus, anthroyl stearate appears to be a useful probe of a proton gradient supported by phenazine methosulfate of Diquat catalyzed electron flow and is the first "non-amine" fluorescence probe utilized for this purpose in chloroplasts.

Anthracenes↗

PubMed1976

Spin-labeled stearates as probes for microenvironment of murine thymocyte adenylate cyclase-cyclic adenosine 3':5'-monophosphate system.

The interaction of various spin-labeled compounds with the murine thymocyte adenylate cyclase-cyclic AMP system was investigated. Electron paramagnetic resonance spectra from spin-labeled compounds were used to calculate the order parameter, S, and indicated that the thymocyte plasma membrane is a relatively rigid structure. Increasing concentrations of spin-labeled stearates, but not their corresponding methyl esters, resulted in increased membrane fluidity, partial lysis, and concomitant complete inhibition of cholera toxin-mediated increases in cyclic AMP content. Upon subsequent isolation of plasma membranes from these cells, cholera toxin-stimulated adenylate cyclase activity was also completely inhibited. Direct addition of spin-labeled stearates, but not spin-labeled methyl stearates, to thymocyte homogenates caused a dramatic reduction of basal, cholera toxin-, isoproterenol-, NaF-, and prostaglandin E1-stimulated adenylate cyclase activity. Inhibition was complete within the first minute of addition to homogenates and required approximately 0.2 mM spin-labeled stearate I(12,3) for half-maximal inhibition. This inhibition occurred in the presence or absence of an ATP-regenerating system and was not readily reversible. Furthermore, since the membrane cyclic phosphodiesterase activity was not altered by spin-labeled stearates, their inhibition was attributed to a direct action of stearate spin labels on adenylate cyclase. Neither stearate, methyl stearate, spin-labeled methyl stearates nor 2,2,6,6,-tetramethylpiperidine-1-oxyl (Tempo) altered cell viability or enzyme activities at the concentrations studied. Spin-labeled stearates seemed to intercalate into different areas of the plasma membrane than their corresponding methyl esters. Furthermore, the action of spin-labeled stearates appeared to be on the exterior of the plasma membrane rather than the interior. These results illustrate the presence of multilipid domains and the importance of selected lipids and lipid-protein interactions in the adenylate cyclase-cyclic AMP system. Thymocyte adenylate cyclase is described in terms of a current model for membrane proteins.

Adenylyl Cyclases↗

PubMed1990

Biological monitoring of workers exposed to lead stearate.

This study was conducted to examine the usefulness of some of the commonly used biological parameters for monitoring of workers exposed to lead stearate. Forty-two lead stearate workers from a lead stabilizer factory and 26 workers exposed to inorganic lead compounds were involved in this study. Although the workers had similar blood lead values (PbB), subjects exposed to lead stearate were found to have a significantly higher concentration of lead in plasma (PbP), 1.0 +/- 0.57 micrograms dl-1) than workers exposed to inorganic lead compounds (0.42 +/- 0.3). The ratio of PbP to PbB was ca. 2.5 times higher for lead stearate workers (0.38) than the inorganic lead workers (0.15). These data suggest that the different chemical properties of lead stearate may result in different distributional patterns of the metal in different blood components. On the other hand, the activity of delta-aminolevulinic acid dehydratase (ALAD), an enzyme highly sensitive to lead, was not so much depressed among the lead stearate workers as that of workers handling inorganic lead. A poor correlation was also observed between PbB and ALAD activity of the stearate workers. These findings indicate that PbB and ALAD are not good biological indicators for evaluating the toxicological effect of lead stearate exposure.

Chemical Industry↗

PubMed1991

A comparative safety and efficacy study of clarithromycin and erythromycin stearate in community-acquired pneumonia.

The efficacy and tolerance of clarithromycin and erythromycin stearate in the treatment of community-acquired pneumonia were compared in a multicentre, double-blind randomized trial. Two hundred and eight adult patients were randomized to receive either clarithromycin 250 mg 12-hourly (96 patients) or erythromycin stearate 500 mg 6-hourly (112 patients), each for 14 days. One hundred and eight patients were evaluable for efficacy, 64 receiving clarithromycin and 44 erythromycin stearate. There was no significant difference between the two groups in terms of clinical cure (52% for clarithromycin, 40% for erythromycin) or clinical success (clinical cure and improvement; 89% for clarithromycin, 98% for erythromycin stearate), or radiological response (90% for both groups). An intention-to-treat analysis, including all patients entering the study revealed significant differences in favour of clarithromycin. The clinical cure rate after two weeks of treatment was 45% in those who received clarithromycin compared with 25% in the erythromycin stearate group (P = 0.003), whilst improvement in cough was observed in 97% and 80% of patients receiving clarithromycin and erythromycin stearate, respectively (P = 0.07). Adverse effects, mainly gastrointestinal, caused discontinuation of treatment in 4% (4/96) patients in the clarithromycin group in comparison with 19% (21/112) treated with erythromycin stearate (P less than 0.01). These results demonstrate that clarithromycin twice daily is at least as effective as four times daily erythromycin stearate for the treatment of community-acquired pneumonia and is better tolerated.

Adult↗

PubMed1991

Hepatic transport of a fluorescent stearate derivative: electrochemical driving forces in intact rat liver.

We determined the effect of varying the transmembrane Na+ electrochemical gradient on extraction of a fluorescent derivative of stearate, 12-N-methyl-7-nitrobenzo-2-oxa-1,3,-diazol-amino stearate (NBD-stearate), by the isolated perfused rat liver. Membrane potential difference (PD) of individual hepatocytes and extraction of NBD-stearate were measured simultaneously under basal conditions and during changes in PD induced by perfusate ion substitutions. Under basal conditions, PD average -30 +/- 1 mV, and extraction of 10 microM NBD-stearate from 1% albumin solutions averaged 0.54 +/- 0.03. Fluorescence microscopy indicated that uptake exhibited a declining portal-to-central gradient in the presence but not absence of Na+. Substitution of nitrate for Cl- hyperpolarized PD to -59 mV and increased extraction to 131% of control values. Withdrawal of nitrate and substitution of gluconate for Cl- depolarized PD to -3 and -15 mV, respectively, and decreased extraction to 63 and 73% of control values. Substitution of choline for Na+ eliminated the out-to-in Na+ gradient, depolarized PD to -16 mV, and decreased extraction to 27% of control values, an effect greater than expected for membrane depolarization alone. Uptake of NBD-stearate was saturable and caused Na(+)-dependent membrane depolarization at higher concentrations (300 microM). These studies indicate that uptake of NBD-stearate occurs in large part by an efficient Na(+)-dependent mechanism compatible with electrogenic Na(+)-fatty acid cotransport.

4-Chloro-7-nitrobenzofurazan↗

PubMed1987

Lead level of whole blood and plasma in workers exposed to lead stearate.

In a group of 23 male workers exposed to lead stearate the levels of lead in whole blood and plasma were determined and compared to those obtained from a group of 23 subjects exposed to inorganic lead compounds. The mean values for lead in whole blood were similar in both groups, while the mean lead concentration in plasma was 0.1729 (SD 0.0677) mumol/l for those exposed to lead stearate and 0.0936 (SD 0.0577) mumol/l for those exposed to other lead compounds. The difference was highly significant. The percentage ratio for lead in plasma to lead in whole blood, which can be considered a "bioavailability index" for lead, proved to be two times higher for stearate workers than for subjects exposed to inorganic lead compounds. The data suggest that the different chemical properties of absorbed lead stearate may cause a different distribution of the metal in different blood compartments, the plasma compartment having a higher affinity for lead stearate than for other lead compounds. Because the plasma fraction has a greater bioavailability, lead stearate could induce toxic effects that differ (possibly being severer) from those caused by other lead compounds at similar absorbed doses.

Air Pollutants, Occupational↗

PubMed1976

[Studies on erythromycin stearate capsules (OE-7) (author's transl)].

The blood concentration and urinary excretion of OE-7 (erythromycin stearate capsules) and control drug were investigated in 6 volunteers having gastroptosis. OE-7, newly arranged capsules containing erythromycin stearate, was investigated and obtained the results of high blood concentration by oral administration. To confirm the above, we measured blood concentration and urinary excretion of OE-7 comparing with ordinary erythromycin stearate capsules in 6 volunteers having gastroptosis. The peaks of blood concentration were noted at 3 hours after administration in 6 volunteers uniformly. The mean maximum blood concentration of OE-7 was 1.17 mcg/ml which was significantly higher than ordinary erythromycin stearate capsules. In time course of mean blood concentration, the blood concentration levels of OE-7 were higher than those of control erythromycin stearate capsules at any measurement. Effective blood levels were continuously high in OE-7. Urinary excretion of OE-7 reached to the maximum from 4 to 6 hours after administration which was also higher than control erythromycin stearate. Clinical efficacy of OE-7 was investigated in 28 cases in acute respiratory infection. The results noted were excellent in 5 cases (17.9%), good in 16 cases (57.1%), no change in 6 cases (21.4%), and undetermined in 1 case (3.6%). There were 5 cases of slight gastro-intestinal discomfort as the side effects. As the conclusion, OE-7 revealed good bioavailability and seemed to be useful antibiotic for acute respiratory infections.

Adult↗

PubMed1989

Determination by gas-liquid chromatography of trace amounts of soft polyvinyl chloride plastic additives in aqueous solutions. II. Di(2-ethylhexyl) phthalate, epoxidized vegetable oils and stearates.

A method for the determination of di(2-ethylhexyl) phthalate (DEHP), epoxidized vegetable oils (EVO) and stearates in aqueous solutions is described. A stepwise extraction procedure is employed to separate DEHP and EVO from the stearates, using n-hexane as extraction solvent. EVO is transesterified to methyl esters by sodium methoxide in methanol. The stearates are derivatized by methanol containing sulfuric acid. The alkyl esters are analyzed by gas-liquid chromatography, using 3% OV-210 as the stationary phase. The concentrations of the weakest standard solutions correspond to 10, 5 and 8 micrograms/l (ppb) of DEHP, EVO and stearates, respectively, in the aqueous samples. The method is used for the determination of DEHP, EVO and stearates in intravenous solutions stored in flexible polyvinyl chloride bags.

Chromatography, Gas↗

PubMed1976

Binding of nitroxide stearate spin labels to bovine serum albumin.

1. 12-Nitroxide stearate binds to bovine serum albumin at about four independent and equivalent binding sites with an association constant of about 10(6) M-1. The binding at these high affinity binding sites is significantly reduced by addition of unlabeled stearate. These data suggest that nitroxide stearates probe the high affinity binding sites for long-chain fatty acids. 2. Qualitative analyses of the ESR spectra of 5-, 12- and 16-nitroxide stearate bound to bovine serum albumin and measurements of the interaction of these compounds so bound with ferricyanide ion provide a rough description of the binding site as follows: the polar headgroup of the spin-labeled fatty acid is rigidly fixed, but fairly accessible to paramagnetic ions. The middle part of the hydrocarbon chain of bound stearate spin label also is rigidly fixed but differs in being shielded from the solvent, presumably by a hydrophobic cleft. The methyl terminus shows greater motion, appearing to move within a narrow cone, and also appears to be somewhat accessible to paramagnetic ions.

Binding Sites↗

PubMed1977

Surface phase separation and collapse of the stearate anion--alkaline earth cation complex.

The surface properties of fatty acid and fatty acid-alcohol mixtures were examined at 22-24 degrees C. At pH 12, sodium stearate forms a rigid surface film that generates an equilibrium spreading pressure of 16.5 dynes/cm. At pH 12, stearate-alkaline earth cation films collapse at the air-water interface and do not generate significant equilibrium spreading pressures. The rate of film collapse depends on the counterion decreasing in the sequence Ba2+ greater than Sr2+ greater than Ca2+. Stearate-stearyl alcohol mixtures form solid (condensed) films that are relatively stable and behave initially as homogeneous surfaces in their selectivities for counterions. Stearate-oleyl alcohol mixtures form fluid (expanded) films that are unstable. Lateral phase separations occur rapidly in fluid films and the stearate-alkaline earth cation phase collapses. The rate of film collapse in the fluid mixtures also depends on the counterion decreasing in the sequence Ba2+ greater than Ca2+. These surface properties suggest how a lipid anion may function as an ionophore in the translocation of alkaline earth cations.

Barium↗

PubMed1976

Gastric acid inactivation of erythromycin stearate in solid dosage forms.

The effect of hydrochloric acid at pH 1.2-3.2 ON ERYTHROMYCIN STEARATE AND COMMERCIAL DOSAGE FORMS OF ERYTHROMYCIN STEARATE WAS STUDIED. Under all conditions examined, erythromycin was readily dissolved from the stearate as hydrochloride, and rapidly lost its biological activity in solution. The inclusion of pepsin in the test systems did not affect the results. Although formulation differences somewhat affected the rate of destruction, acid lability was exhibited by all products examined, except enteric-coated tablets. Amounts of acid considered to be normal in the fasting stomach contents of adults during the time likely for a dose to remain in the stomach caused 70-90% destruction within 15 min after the shells started to rupture. Amounts of hydrochloric acid appreciably less than 1 mEq, representing abnormally small quantities even in the fasting state, caused destruction ranging from 30 to 70% of the doses in 15 min. These results are not reconcilable with published statements that the sensitivity of erythromycin to gastric acid is overcome by providing the antibiotic in the form of stearate salt.

Capsules↗

PubMed1979

Plasma levels following single and repeated doses of erythromycin estolate and erythromycin stearate.

The pharmacokinetics of erythromycin and erythromycin 2'-propanoate were studied in healthy male volunteers following single and repeated doses of erythromycin stearate tablets, erythromycin estolate capsules, and a suspension. Estolate dosages gave rise to higher plasma levels of total drug than the stearate. However, the stearate yielded higher plasma levels of erythromycin base. Absorption of all dosage forms, except the suspension, was delayed, and pharmacokinetic interpretation of both single- and multiple-dose data required incorporation of an absorption lag time. The absorption of erythromycin stearate was inhibited by food and also by low fluid volumes in fasted subjects. Absorption of erythromycin estolate was increased in the presence of food and was not greatly affected by fluid volume. Although single-dose data poorly predicted circulating levels of erythromycin following repeated doses, trends observed after single doses were maintained during chronic treatment.

Adult↗

PubMed1989

Compaction properties of microcrystalline cellulose and sodium sulfathiazole in combination with talc or magnesium stearate.

The dynamic indentation hardness, tensile strength, bonding index, and brittle fracture index were employed to investigate the compaction properties of a plastic excipient, microcrystalline cellulose, and a brittle drug, sodium sulfathiazole, in combination with different levels of either magnesium stearate or talc. These parameters were also used to quantitate properties of various combinations of microcrystalline cellulose and sodium sulfathiazole in order to illustrate the effects of combining a plastic excipient and a brittle drug. It was shown that the tensile strength, indentation hardness, bonding index, and brittle fracture index for compacts composed of microcrystalline cellulose in combination with either talc or magnesium stearate generally decreased as the amount of talc or magnesium stearate was increased over the concentration range of 0 to 9%. Similar results were observed for admixtures of sodium sulfathiazole in combination with either talc or magnesium stearate. It was also demonstrated that the tensile strength, indentation hardness, and bonding index increased, and the brittle fracture index decreased, as the percent of microcrystalline cellulose was increased in a binary mixture of sodium sulfathiazole and microcrystalline cellulose.

Cellulose↗

PubMed1977

Metabolism of arachidonate and stearate injected simultaneously into the mouse brain.

The metabolism of a polyunsaturated and a saturated fatty acid in brain membrane phosphoglycerides was examined by injecting simultaneously a mixture of 14C-arachidonate and 3H-stearate into the mouse brain and isolating the microsomal and synaptosomal fractions at 1-40 min after injections. Both types of labeled fatty acids were utilized more readily in the microsomal than the synaptosomal fractions in brain. However, labeled arachidonate was incorporated more rapidly into membrane phosphoglycerides than was stearate. In both subcellular fractions, the relative specific radioactivity (3H and 14C) of diacyl-glycerophosphorylinositol (diacyl-GPI) was higher than other types of phosphoglycerides such as diacyl-glycerophosphorylcholine (diacyl-GPC) and diacyl-glycerophorylethanolamine (diacyl-GPE). Furthermore, the apparent rates of incorporation of radioactivity into diacyl-GPI was more rapid for the 14C-arachidonate than for the 3H-stearate. Results of the experiment have demonstrated obvious differences in metabolism between stearate and arachidonate in brain. The more rapid transfer of arachidonate to diacyl-GPI is probably due to the presence of an acyl transferase system specially active for the transfer of arachidonyl groups to diacyl-GPI.

Animals↗

PubMed1985

Influence of the granulation technique and starting material properties on the lubricating effect of granular magnesium stearate.

Magnesium stearate has been granulated in four ways to produce lubricant granulations with different properties. The lubricating properties, as well as the tablet properties with the granulated lubricant, were evaluated on tablets prepared from a mixture of dicalcium phosphate, corn starch and microcrystalline cellulose. The lubricating effect of the magnesium stearate granulations showed a similar pattern regardless of the granulation technique used except for a granulation with providone. Increasing the particle size of the magnesium stearate granulation increased the amount of lubricant required to obtain lubrication similar to powdered magnesium stearate. Variations in the specific surface area of the starting materials could be masked by using them in granular form.

Chemistry, Pharmaceutical↗

PubMed1976

Effect of dietary palmitate, stearate, oleate and linoleate on the tissue lipid and systolic blood pressure of the rat.

The nutritional effects of palmitate, stearate, oleate and linoleate were correlated with the percentage of each fatty acid in the dietary lipid but were found to be largely independent of the total amount of fat in the diet. Increasing the proportion of linoleate in diet fat to levels as high as 52% of the fat, increased theproportion of fat observed in the carcass. Increased linoleate and/or oleate resulted in increased concentrations of cholesterol in body fat deposits. The maximum weight of the perirenal fat pads occurred when diet fat contained about 43% oleate and 19% stearate. Increasing the stearate decreased the cholesterol concentration in plasma. The systolic blood pressure was decreased slightly when the amount of diet fat was increased.

Adipose Tissue↗

PubMed1992

[The effect of two lubricants (magnesium stearate and pruv) in the formation of tablets of four anti-ulcer agents/ by means of direct compression].

In this research we study the influence of two lubricants-Magnesium Stearate and Pruv--on the tablets elaboration of Cimetidine, Ranitidine, Famotidine and Pirenzepine by direct compression. The presence of 0.5% of lubricants improved the flow of all the formulations, but especially the Famotidine's formulation. The formulations with Magnesium Stearate had the worst results in tests of friability and tensile strength. All tablets with drugs and Pruv had high data in indentation hardness. The tablets of Cimetidine, Famotidine and Pirenzepine with Magnesium Stearate had less time of disintegration.

Anti-Ulcer Agents↗