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PubMed1981

The bioavailability of erythromycin stearate versus enteric-coated erythromycin base when taken immediately before and after food.

1. Erythromycin plasma concentrations were determined in twenty subjects after a single dose, immediately before food, of erythromycin, 500 mg. as: (1) erythromycin stearate (Erythrocin, 500 mg, ovaloid tablets), and (2) erythromycin base (Eryc, 250 mg, capsules containing enteric-coated pellets). 2. Plasma concentrations were again determined in eighteen of the original subjects with the same dose given immediately after food. 3. Maximum Plasma Concentrations (mcg/ml) (See formula in text) 4. Erythromycin stearate was more bioavailable than erythromycin base when administered immediately before food. The preparations were bioequivalent when given immediately after food.

Biological Availability↗

PubMedDate not supplied

Asymptomatic liver injury due to erythromycin stearate.

A 73-year-old woman with rosacea, who had started treatment with erythromycin stearate 2 g/d, developed asymptomatic liver injury. The drug was discontinued and the laboratory findings of liver damage disappeared within 11 days. This is the first report of erythromycin stearate-induced asymptomatic hepatotoxicity.

Aged↗

PubMed2006

Acute eosinophilic pneumonia caused by calcium stearate, an additive agent for an oral antihistaminic medication.

A 70-year-old man was admitted to our hospital because of dyspnea after taking an antihistaminic agent (homochlorcyclizine hydrochloride) for itching. Chest roentgenogram showed infiltration in the left lung field, and laboratory data revealed eosinophilia. Examination of the bronchoalveolar lavage fluid revealed an increased eosinophil count. A drug lymphocyte stimulation test was positive only for calcium stearate, an additive contained in the homochlorcyclizine hydrochloride tablet. The pulmonary infiltration and clinical symptoms subsided after withdrawal of all drugs and initiation of glucocorticoid therapy. Therefore, we concluded that this patient's pulmonary disease was caused by calcium stearate, an additive for an antihistaminic drug. An allergic reaction to a drug's additive material should be considered as a rare cause of drug-induced acute eosinophilic pneumonia.

Acute Disease↗

PubMedDate not supplied

Acute otitis media in older children and adults treated with phenoxymethyl penicillin or erythromycin stearate. Bacteriological and immunological aspects.

Seventy-eight patients, all over 10 years of age, with clinical signs of acute otitis media, received either phenoxymethyl penicillin or erythromycin stearate, in a randomized manner, and the clinical, bacteriological and immunological effects were studied. Haemophilus influenzae and Streptococcus pneumoniae were the major pathogens isolated from the nasopharynx in 30 and 28 patients, respectively. Increased levels of C-reactive protein (CRP) were detected in 53 (68%) of the patients. There was no statistical difference in the CRP-levels depending on species of bacteria isolated. The highest incidence was observed in cases with Branhamella catarrhalis and H. influenzae. Persistence of H. influenzae during antibiotic therapy was demonstrated in 70% and after therapy in 63% compared to 4% and 11% persistence of S. pneumoniae. The type of antibiotic treatment did not influence persistence. An immune response to H. influenzae and S. pneumoniae was detected significantly more often in patients treated with erythromycin stearate than with phenoxymethyl penicillin.

Acute Disease↗

PubMed1992

Efficacy and tolerance of roxithromycin in comparison with erythromycin stearate in patients with lower respiratory tract infections.

The efficacy and tolerance of roxithromycin 150 mg b.i.d. were compared with those of erythromycin stearate 500 mg b.i.d. in patients with lower respiratory tract infections. Out of 86 patients recruited for the study, 79 were evaluable for tolerance and 76 for efficacy. These patients were evenly distributed among the 3 investigational clinics, with 26, 25 and 28 patients, respectively. The diagnosis of lower respiratory tract infections was based on clinical, laboratory, radiological and/or physical findings and, when available, bacteriological and serological findings. The duration of treatment was 10 days, with follow-up at post-treatment visits directly after treatment and 6 weeks thereafter. The clinical outcome was satisfactory with no significant difference between the drugs. More patients reporting adverse events were on erythromycin than on roxithromycin (51.3% vs 17.5%; p = 0.003). The results suggest that roxithromycin is as effective as erythromycin stearate in the treatment of lower respiratory tract infections and causes fewer adverse effects.

Adult↗

PubMed1975

Multiple thermotropic phase transitions in Escherichia coli membranes and membrane lipids. A comparison of results obtained by nitroxyl stearate paramagnetic resonance, pyrene excimer fluorescence, and enzyme activity measurements.

At characteristic temperatures, membranes from Escherichia coli cells enriched in exogenous elaidic acid exhibit two abrupt changes in the slope of Arrhenius plots of two enzyme activities. For NADH oxidase, these changes occur at 27 degrees and 32 degrees, whereas for D-lactate oxidase, these changes occur at 31 degrees and 36 degrees. Pyrene excimer fluorescence and spin-labeled fatty acid paramagnetic resonance results indicate that the beginning, midpoint, and end of a single structural change(order leads to disorder transition) occurs at 25.5-29.0 degrees, 30.0-31.0 degrees, and 33.0-35.5 degrees, respectively. These data suggest that for NADH oxidase, the observed activity changes correspond to the beginning and midpoint of a single membrane lipid structural change, whereas for D-lactate, the activity changes correspond to the midpoint and end of that structural change. In addition to the membrane structural change spanning the range of 25.5-35.5 degrees, a second change (9.5-21.0 degrees) was also observed. This transition was detected by 5- and 16-2,2-dimethyloxazolidinyl-1-oxyl (doxyl) stearates, but not by 12-doxyl stearate or pyrene. Structural changes in the extracted lipids were observed in the temperature ranges 4.0-9.0 degrees, 14.0-20.0 degrees, and 25.0-35.5 degrees. The two higher ranges correlate well with the ranges for structural changes observed in the intact membrane. Observations of these multiple transitions in both intact membranes and extracted lipids strongly suggest that these lipids segregate into domains of different fluidity and composition.

Cell Membrane↗

PubMed1967

Properties, composition, and structure of stearic acid-stearate monolayers on alkaline earth solutions.

Interactions between alkaline earth ions and the carboxylate ligand in a stearic acid surface film have been investigated by IR spectrophotometry and surface chemical procedures. The frequency and shape of the carboxylate absorption band and the effect of hydration and pH on band characteristics suggest that beryllium, magnesium, and calcium ions form calcium-type complexes with the stearate ligand while strontium and barium ions form both calcium-type complexes and more ionic barium-type complexes, which have lower carboxylate band maxima. Since IR band frequencies in anhydrous calcium-type complexes are directly proportional to the charge/(crystal radius) ratio, it is apparent that covalency decreases in the order: Be > Mg > Ca > Sr > Ba. The decreasing order of stability constants estimated from spectrophotometric titration data, Be > Ca > Mg > Sr > Ba, demonstrates that calcium behaves anomalously. This anomalous behavior is also apparent in the high solid-to-liquid phase transition temperature and small surface area of the calcium-carboxylate film compared to films composed of complexes with the other ions. A geometric factor related to the ionic radius and the radius of the carboxylate binding site formed by a calcium stearate lattice is proposed to explain the unique properties of calcium-carboxylate surface films. Although the beryllium complex has the highest carboxylate band frequency and stability constant, it gives an atypical "expanded" surface film. A hydrogen bonded lattice formed with a soluble beryllium monohydrate is suggested as an explanation for this film property.

Barium↗

PubMedDate not supplied

Chemoprophylaxis with erythromycin stearate or amoxycillin in patients with chronic bronchitis--effects on cellular and humoral immune functions.

Twenty-six patients aged between 27 and 71 years with chronic bronchitis were divided into a control group of 6 and two groups of 10 patients each who received either erythromycin stearate or amoxycillin 1500 mg/d for 2 weeks and 1000 mg/d for 12 weeks thereafter. Immunological function tests were performed before starting chemotherapy and thereafter at 2 weeks and 14 weeks. Clinical evaluations and lung function tests showed no significant changes in any of the groups during the study period. In the control group no changes in cellular and humoral immune functions were noted. In the group receiving amoxycillin decreased responses of lymphocytes to the mitogen phytohaemagglutinin were observed after 14 days. In the erythromycin-treated group, increased polymorphonuclear leucocyte (PMNL) motility and mitogen-induced transformation were observed at 14 days but these increases were not statistically significant. In this group the markedly depressed PMNL migration found in 3 individuals before treatment improved considerably. These results indicate that chemotherapy and chemoprophylaxis with either amoxycillin or erythromycin stearate do not compromise the host immunodefences.

Adult↗

PubMed1982

Adrenal and hepatic calcium stearate crystal deposits in dogs fed a thiamine-deficient diet.

The nature and histologic environment of birefringent crystals found incidentally at necropsy in the liver and adrenal glands of dogs fed a thiamine-deficient diet were studied. The crystals were identified as calcium stearate by ultrastructural and x-ray microdiffraction techniques. Crystals were observed intracellularly within cytoplasmic vacuoles and extracellularly within sinusoids. Generally, crystals were also observed in pair-fed controls that were given a purified diet (equal in weight to that consumed by the thiamine-deficient animals) plus supplemental thiamine. Crystal deposits were found in trace amounts in a few of the ad libitum-fed controls. Although thiamine deficiency may be involved in promoting crystal deposition in the adrenal cortex, calcium stearate crystal formation within the adrenal glands and the liver appears unrelated to dietary thiamine deficiency per se, but is probably related to deficiency of an unidentified nutrient in the purified thiamine-deficient diet.

Adrenal Glands↗

PubMed1980

Correlation of in vivo bioavailability of erythromycin stearate tablets with in vitro tests.

Correlations between the bioavailability parameters for erythromycin stearate tablets from five manufacturers and in vitro tests of these tablets were examined using forward (stepwise), multiple linear regression analysis. Bioavailability parameters were determined in clinical studies employing a balanced, incomplete block design. In vitro tests used disintegration, dissolution, and dissolution/dialysis as the independent variables in regression equations. Significant correlations were found between linear combinations of these parameters and the time of peak and the peak serum levels. The inclusion of an in vitro disintegration test to describe peak serum levels of erythromycin is noteworthy since it has been suggested that disintegration tests are of less value than dissolution techniques employed in the present investigation may be useful for selection of appropriate physicochemical tests for continued monitoring of the bioavailability of erythromycin stearate tablets.

Biological Availability↗

PubMed1975

Instability of Langmuir-Blodgett layers of barium stearate, cadmium arachidate and tripalmitin, studied by means of electron microscopy and infrared spectroscopy.

Results of an investigation of the stability of n-layers of barium stearate, cadmium arachidate and tripalmitin by means of electron microscopy and attenuated total reflection infrared spectroscopy are reported. Odd and even numbered barium starate n-layers with n - 1,2,3,4,5 are found to rearrange spontaneously from a regular film into ultrastructures of irregular, flat islands of varying thickness. The kinetics of the phase transformation of the first layer depends on the substrate, that of n-layers appears to be dependent on n, the temperature, and the surrounding medium. The kinetic behaviour of odd and even numbered layers is distinctly different. Similar studies on cadmium arachidate layers reveal much slower kinetics of the rearrangement process. In the case of tripalmitin n-layers it is shown that electron microscopy and infrared spectroscopy yield valuable complementary information about ultrastructure and molecular structure of the layers in correlation with the rearrangement process, which also occurs with this system. Consequences of the results of this paper for work published in various fields are briefly discussed.

Barium↗

PubMed1979

Fatty acid metabolism of the calanoid copepod Paracalanus parvus: 2. Palmitate, stearate, oleate and acetate.

The de novo biosynthesis of fatty acids in the wild, calanoid copepod Paracalanus parvus was studied. The incubation of labeled acetate proved the de novo biosynthesis of saturated and monounsaturated even fatty acids from 14 to 20 carbons and the 22:1 acid. Saturated and monounsaturated uneven fatty acids from 15 to 21 carbons were also synthesized. The copepod could not synthesize linoleic and alpha-linolenic acids. By administration of [1-14C]palmitate, [1-14C]stearate and [1-14C]oleate, it was possible to elucidate the general pattern of the de novo biosynthesis of fatty acids in the wild P. parvus.

Acetates↗

PubMed1987

Comparative studies on additive effects of sodium dodecylbenzensulfonate and sodium stearate on uptake of chemicals by willow shiner (Gnathopogon caerulescens).

Comparative studies between sodium dodecylbenzensulfonate (DBS) and sodium stearate (SNa) were performed on the additive effects of the uptake of chemicals in a fresh water fish, the willow shiner (Gnathopogon caerulescens), by the use of a continuous flow water system. The chemicals selected were 2,4,6-trichlorophenyl-4'-nitrophenyl ether (CNP) as a non-polar lipophilic substance and cadmium salt (Cd) as polar hydrophilic substance. DBS had no promotive and depressive effects on the uptake of Cd. SNa had no promotive and depressed effects on the uptake of CNP and Cd.

Animals↗

PubMed2005

Dynamics and partitioning of spin-labeled stearates into the lipid domain of stratum corneum.

The EPR spectra of the positional isomers n-doxyl stearic acids (n-DSA), with n=5, 12 and 16, and 5-doxyl methyl stearate (5-DMS) structured in the lipid domain of intact stratum corneum (SC), are characterized by the thermodynamic equilibrium of two distinct spectral components provided by two different motional states of the spin-labeled chains. A two-component model used in the EPR spectra simulations provided the relative populations of the components, allowing for the calculation of the thermodynamic profile. Based on a detailed investigation, the more motionally restricted population of spin labels (component 1) is found to arise when the spin label is hydrogen-bonded to the polar surfaces of the membranes, while the less motionally restricted population (component 2) is generated by spin labels nonhydrogen-bonded and more deeply inserted in the hydrophobic core. The 5-DSA is bound tightly to the polar surfaces (DeltaG(o)2 --> 1=-1.75 kcal/mol and DeltaH(o)2 --> 1=-13.8 kcal/mol), whereas the more lipophilic 5-DMS has a major spin population stabilized in the hydrophobic core (DeltaG(o)2 --> 10.57 kcal/mol and DeltaH(o)2 --> 1=-9.1 kcal/mol). Upon lipid-depleting SC increases the interactions of the probe with the polar surfaces, thereby decreasing its rotational diffusion. In contrast, the treatment of SC with oleic acid, a permeation enhancer, drastically increases the mobility of the spin labels, particularly that of component 1, and the thermodynamic equilibrium shifts towards the formation of component 2. A mechanism for water permeation in SC is also proposed.

Animals↗

PubMed2000

Spin-labeling study of membranes in wheat embryo axes. 1. Partitioning of doxyl stearates into the lipid domains.

The interaction of lipid soluble spin labels with wheat embryo axes has been investigated to obtain insight into the structural organization of lipid domains in embryo cell membranes, using conventional electron paramagnetic resonance (EPR) and saturation transfer EPR (ST-EPR) spectroscopy. Stearic acid spin labels (n-SASL) and their methylated derivatives (n-MeSASL), labelled at different positions of their doxyl group (n=5, 12 and 16), were used to probe the ordering and molecular mobility in different regions of the lipid moiety of axis cell membranes. The ordering and local polarity in relation to the position of the doxyl group along the hydrocarbon chain of SASL, determined over the temperature range from -50 to +20 degrees C, are typical for biological and model lipid membranes, but essentially differ from those in seed oil droplets. Positional profiles for ST-EPR spectra show that the flexibility profile along the lipid hydrocarbon chain does exist even at low temperatures, when most of the membrane lipids are in solid state (gel phase). The ordering of the SASL nitroxide radical in the membrane surface region is essentially higher than that in the depth of the membrane. The doxyl groups of MeSASLs are less ordered (even at low temperatures) than those of the corresponding SASLs, indicating that the MeSASLs are located in the bulk of membrane lipids rather than in the protein boundary lipids. The analysis of the profiles of EPR and ST-EPR spectral parameters allows us to conclude that the vast majority of SASL and MeSASL molecules accumulated in embryo axes is located in the cell membranes rather than in the interior of the oil bodies. The preferential partitioning of the doxyl stearates into membranes demonstrates the potential of the EPR spin-labelling technique for the in situ study of membrane behavior in seeds of different hydration levels.

Biophysical Phenomena↗

PubMed1996

Evaluation of stearate-graphite paste electrodes for chronic measurement of extracellular dopamine concentrations in the mammalian brain.

Chronoamperometric procedures, in combination with pharmacological treatments, were used to verify whether stearate-modified graphite paste recording electrodes (SGEs) could measure basal extracellular dopamine (DA) concentrations in the striatum of awake rats over a 3-week period of implantation. Baseline chronoamperometric signals were unaffected by systemic injections of ascorbate (AA) or the monoamine oxidase inhibitor pargyline, or by intraventricular infusions of the AA degrading enzyme AA-oxidase. In contrast, systemic injections of d-amphetamine or nomifensine increased, and gamma-butyrolactone decreased, the signal in a reproducible fashion over a similar test period. In addition, 6-hydroxydopamine lesions of the nigrostriatal DA pathway attenuated the ability of d-amphetamine to increase, and gamma-butyrolactone to decrease, the chronoamperometric signal. In separate studies, reverse microdialysis, performed with dialysis probes implanted directly adjacent to SGEs in the striatum, permitted the assessment of electrode selectivity, sensitivity, response linearity, and detection limits to DA. Perfusion of the probe with normal Ringer solution (5 microliters/min) decreased the baseline chronoamperometric signal by 10 nA. Comparable decreases in the baseline signal were observed after systemic injections of gamma-butyrolactone or medial forebrain bundle infusions of tetrodotoxin, suggesting these decreases reflected depletion of extracellular DA to levels below the electrode's detection limit. Reverse dialysis with high concentrations of AA, DOPAC, 5-HT, or 5-HIAA, failed to reverse the decrease in the chronoamperometric signal induced by dialysis. In contrast, reverse dialysis with a physiologically relevant range of DA concentrations, in rats pretreated with the DA uptake blocker nomifensine, increased the chronoamperometric signal in a linear fashion with a detection threshold of < 20 nM. Combined, these results indicate that the baseline chronoamperometric signals recorded at +0.20 V in the striatum with SGEs do not reflect changes in extracellular concentrations of AA, DA metabolites, or indoles, but rather represent neuronally mediated nanomolar changes in extracellular DA concentrations, even after extended periods of implantation in brain tissue.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2002

The effect of fatty acid substitution on the in vitro release of amphotericin B from micelles composed of poly(ethylene oxide)-block-poly(N-hexyl stearate-L-aspartamide).

The effect of fatty acid substitution on the in vitro release of amphotericin B (AmB) from micelles composed of poly(ethylene oxide)-block-poly[N-(6-hexyl stearate)-L-aspartamide] (PEO-b-PHSA) was investigated. PEO-b-PHSA at 11, 50 and 70% of stearic acid substitution self assembled into micelles that effectively encapsulate AmB by solvent evaporation and dialysis methods. The sustained release of AmB from PEO-b-PHSA micelles was evidenced, by measuring the transfer of the drug to lipid vesicles [dipalmitoyl phosphatidylcholine:cholesterol:dimyristoyl phosphatidyglycerol (3:1:0.25)]. The release of AmB for PEO-b-PHSA micelles was markedly influenced by the degree of fatty acid substitution--as it increased, the release of AmB slowed. Accordingly, drug release was found to correlate with haemolysis induced by AmB encapsulated in PEO-b-PHSA micelles. At 11% stearic acid substitution, encapsulation of AmB had little effect on the drug's ability to induce untoward haemolysis. In contrast, AmB stably encapsulated in PEO-b-PHSA micelles at 50 and 70% caused no hemolysis up to 20 microg/ml. Lastly, PEO-b-PHSA micelles at 50 and 70% were able to elute entirely as micelles during size-exclusion chromatography, indicating their stability toward dissociation after dilution. The results point to a nanoscopic drug depot that may release AmB at controlled rates.

Amphotericin B↗

PubMed1990

Stearate-modified carbon paste electrodes for detecting dopamine in vivo: decrease in selectivity caused by lipids and other surface-active agents.

Electrochemical characteristics of dopamine, ascorbic acid, and ferrocyanide measured with carbon-Nujol paste electrodes (CPEs) and stearate-modified carbon paste electrodes (SMEs) before and after treatment with either surfactant (Triton-X), lipid (phosphatidylethanolamine), or brain tissue indicate that the lipophilic nature of the brain destroys the selectivity of SMEs for dopamine by removing the hydrophobic elements from the electrode surface. Measurements of the degree and time-course of changes in surface capacitance of SMEs following contact with surface-active agents support this conclusion. The results suggest that SMEs cannot be used to detect dopamine unambiguously in vivo and emphasize the need to characterize electrochemical sensors in an environment similar to that of intended applications.

Carbon↗