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At least 199 records · Page 11Linked to original sources
PubMed2006

Enhancement of dissolution of cyclosporine A using solid dispersions with polyoxyethylene (40) stearate.

A solid dispersion containing cyclosporine A (CyA) and polyoxyethylene (40) stearate (PS) was prepared by the solvent-melt method and characterized by powder X-ray diffraction (PXRD), hot-stage microscopy (HSM), scanning electron microscopy (SEM) and dissolution studies. The crystalline peaks of CyA disappeared in the PXRD spectra of solid dispersions but were seen in those of physical mixtures, demonstrating the amorphous state of the drug in solid dispersions. The solubility of CyA in aqueous solutions of PS was increased linearly with increasing amount of PS in water. Dissolution of the drug from solid dispersions and physical mixtures was dramatically enhanced compared to the drug powder alone in water at 37 degrees C.

Algorithms↗
PubMed1987

Effects of incomplete ischemia and subsequent recirculation on free palmitate, stearate, oleate and arachidonate levels in lumbar and cervical spinal cord of rabbit.

The effect of severe incomplete ischemia, induced by abdominal aorta ligation for 40 minutes, and subsequent recirculation for one and four days on accumulation of free fatty acids was studies in the lumbar and cervical part of rabbit spinal cord. Changes in free fatty acid levels were determined separately in gracile fascicle (Fg), dorsal part (Dp, without Fg) and ventral part (Vp) of both spinal cord regions. In lumbar spinal cord increases in free fatty acid levels, especially that of arachidonate, were observed in Fg, Dp and Vp a the end of the ischemic period. During recirculation all values were similar to nonischemic controls. In cervical spinal cord a slight increase in free fatty acid levels was found in Fg after four days of recirculation, and in Dp arachidonate and stearate levels were most markedly elevated after one day of recirculation. No changes at any interval were found in Vp of cervical spinal cord. The present results indicate that the experimental insult induced typical ischemic injury to spinal cord tissue demonstrated by fatty acid liberation from membrane lipids. This injury may affect neurotransmission and other processes and free fatty acids themselves impair tissue metabolism (inhibition of oxidative phosphorylation, edema precipitation, synthesis of eicosanoids) and thus restrict the possibilities to enhance recovery in the recirculation period.

Animals↗
PubMed1988

Human pharmacokinetics of erythromycin propionate-N-acetylcysteinate: comparative evaluation with erythromycin stearate and N-acetylcysteine.

The pharmacokinetic pattern of erythromycin propionate-N-acetylcysteinate (EPAC) (erythromycin stinoprate I.N.N.), a new derivative, was studied on 12 healthy volunteers after single and multiple oral treatments. Microbiological and/or HPLC analytical methods were used to titer either erythromycin as base, propionate and total or N-acetylcysteine (NAC). In the acute experiment, a comparative evaluation was performed with erythromycin stearate (ES) and with N-acetylcysteine, according to a randomized-multi-crossover design. EPAC showed a better bioavailability than ES with longer-lasting serum levels of active antibiotic. NAC concentrations in the serum after EPAC were practically identical to those found after an oral administration of NAC alone. The multiple treatment study, performed in the same 12 volunteers with only EPAC, indicated that the pharmacokinetic pattern is somewhat different from that observed after a single dose, since higher concentrations were present at the steady state conditions.

Acetylcysteine↗
PubMed1987

The value of comparative bioavailability studies of marketed drugs in drug control. An example with erythromycin stearate.

As a part of the quality control of drugs The National Medicine Control Laboratory in Finland has started comparative bioavailability studies of synonym preparations in human volunteers by taking all the products containing the same active ingredients for absorption studies at the same time. The first study, which is presented as an example of the importance of these studies, covered three erythromycin stearate preparations containing 250 mg of erythromycin. 12 volunteers took 2 tablets of every product at one week intervals in a cross-over fashion, and the serum erythromycin levels were measured microbiologically for 12 hr. Disintegration and dissolution tests were also performed. One of the products was coated with an acid-resistant film and was not dissolved in pH 1.2, whereas the conventional tablets lost all antimicrobial activity after 15 min in pH 1.2. In phosphate buffer, pH 6.6, all the tablets dissolved rapidly and retained antimicrobial activity. One of the conventional tablets showed only a 50% bioavailability as compared to the two others and was subsequently withdrawn from the market. Thus, it is important to conduct comparative post-marketing bioavailability studies with drugs which earlier have shown good bioavailability.

Adult↗
PubMed1979

Erythromycin levels in serum during treatment with erythromycin stearate and base.

The serum concentrations of erythromycin during treatment with erythromycin stearate and erythromycin base were compared in a randomised cross-over study with 21 hospital patients. No statistically significant differences between the brands were found in the serum erythromycin levels at any time or in the areas under the serum level-time curve.

Administration, Oral↗
PubMed1981

Comparison of serum erythromycin concentration following administration of 100 mg erythromycin ethyl succinate intramuscularly and 500 mg erythromycin stearate orally.

Serum erythromycin concentrations were estimated following administration of 100 mg erythromycin ethyl succinate intramuscularly and 500 mg erythromycin stearate orally. The subjects (30 healthy students) were randomly divided into two groups and each subject received a single dose of the alternate form of the drug after a 4-week interval. Blood samples were obtained at 0.5, 1, 1.5, 2, 3 and 4 h after administration by separate venepuncture. All 30 subjects recorded serum levels above 0.2 microgram/ml following administration of the intramuscular form of the drug. Following administration of the oral form of the drug, five subjects failed to record serum levels above 0.2 microgram/ml by the 2-h sampling time and three failed to do so by the 4th hour. It is concluded from the results that, despite the high serum levels recorded with the oral form when taken with food, the intramuscular route gives a greater assurance of consistent absorption into the blood stream. This result suggests that the use of the oral form of the drug as a prophylactic antibiotic in patients receiving dental treatment remains in doubt.

Administration, Oral↗
PubMed1997

Increased synthesis of cholesterol stearate in flanking organ from gonadectomized female hamsters treated with progesterone and 5 alpha-dihydroprogesterone.

We demonstrated for the first time that progesterone and 5 alpha-dihydroprogesterone stimulate [U-14C]glucose incorporation into lipids in gonadectomized female hamster flanking organs. We also found that cholesterol stearate is the major lipid synthesized female hamster flanking organs under progesterone and 5 alpha-dihydroprogesterone stimulation. In this manner, progesterone and 5 alpha-dihydroprogesterone alter the consistency of sebum from gonadectomized female glands.

5-alpha-Dihydroprogesterone↗
PubMed1995

Regulatory effect of various steroid hormones on the incorporation and metabolism of [14C]stearate in rat hepatoma cells in culture.

We have examined the incorporation and metabolism of [14C] stearic acid within the total lipids of HTC rat-hepatoma cells in suspension culture in presence and in absence of steroidal hormone stimulation. Both, glucocorticoids (dexamethasone, cortisol and corticosterone) and mineralocorticoids (deoxycorticosterone and aldosterone) as well as the estrogen beta-estradiol and the androgen testosterone enhanced the extent of delta 9 desaturation to oleic acid of the saturated precursors, whereas only the two mineralocorticoids affected the incorporation rate of the exogenous acid into total cellular lipids, thus promoting a little stimulation. Furthermore, all the hormones tested increased the radiolabelling of the total cellular phospholipids except deoxycorticosterone and testosterone, the former having no effect and the latter exerting a moderate inhibition. On the other hand, the incorporation of 14C into neutral lipids was stimulated by testosterone, in contrast to the inhibition of this parameter observed exclusively with either the mineralocorticoids or the estrogen. Within the phospholipid subclasses, the radiolabelling of phosphatidylcholine was augmented by means of all the steroids tested save deoxycorticosterone and testosterone, whereas phosphatidylethanolamine exhibited a decrease only in the presence of testosterone. In a similar fashion, within the neutral lipids, the predominating triglyceride fraction was preferentially labelled--at the expense of other subclasses of lesser abundance--upon treatment with the steroids except aldosterone, which exerted no effect. The results obtained were correlated with those changes observed in the mass distribution of the different lipid subclasses either with or without prior hormonal stimulation.

Animals↗
PubMed1976

Lanthanum and some other cation-induced changes in fluidity of synaptosomal membrane studied with nitroxide stearate spin labels.

Using nitroxide fatty acid spin labels, the effects of some cations such as La3+, Cd2+ and Hg2+ on synaptosomal membranes were studied by observing changes in their ESR spectra. The labels were incorporated almost instantaneously into synaptosomes isolated from rat brain cortex. ESR spectra of the spin-labeled synaptosomes were significantly braodened immediately upon adding La3+, Ce3+, Cd2+ or Hg2+ but hardly affected by Ca2+, Sr2+ and Ba2+. The magnitude of the change in the separation of the outer two peaks in ESR spectra (2T') depends on the number (n) of methylene units between the polar head group and the spin-label (nitroxide) group; that is, it increases with decreasing n. Among these ions, the effect of La3+ was the greatest and appeared to be in parallel with the amount of La3+ bound with the synaptosomes. On the other hand, K+, Rb+ or Li+ causes hardly any significant changes.

Animals↗