["Non-solvent shock agglomeration"--the technology of a new alternative method for determination of ibuprofen. 6. Stability of s(+)-ibuprofen]. / Die "Non-solvent shock agglomeration"--Technologie als neuartige alternative Methode zur Aufarbeitung von Ibuprofen. 6. Mitt.: Stabilitätsuntersuchungen an S(+)-Ibuprofen.

Due to its low melting range approx. 53 degrees C optically pure ibuprofen can be regarded as problematic in a pharmaceutic-technological sense. With regard to the non-solvent shock agglomeration method this means that the process and product temperatures must strictly be kept in the range of 10 K above the melting point of the substance. Higher temperatures can induce degradation of S(+)ibuprofen. During storage under stress conditions (31 degrees C for a period of 18 months) ibuprofen shows extreme stability independent of its optical activity. Racemic ibuprofen is inert to the influence of light; in individual cases optically pure substance containing an increased level of impurities can show slight degradation tendencies. The thermal and photo stability of ibuprofen is independent of the preparation technology. For comparison, conventional, fluid bed granulated, briquetted and from organic solvents especially recrystallised and optically active substances were investigated besides the shock agglomerated substances.

The in vivo effects of beta-3-receptor agonist CGP-12177 on thyroxine deiodination in cold-exposed, sympathectomized rat brown fat.

OBJECTIVE: The effects of the beta-3-receptor agonist CGP-12177 on thyroxine (T4) deiodination in sympathectomized (SX) interscapular brown adipose tissue (BAT) were assessed in 300 g body weight (BW) Wistar rats. DESIGN: Seven days after SX, groups of rats were implanted s.c. with pellets containing 5mg CGP-12177 or 5mg norepinephrine (NE) and were immediately placed at 4 degrees C for 24h. Other SX groups were injected with CGP-12177 or NE 1mg/kg BW i. p. and placed in the cold for 4h. The latter group was injected, in addition, with prazosin 0.4 mg/100g BW i.p. or propranolol 0.5mg/100g BW i.p. 15 min before and 2h after the administration of CGP-12177 or NE. METHODS: Two hours after the last injection of prazosin or propranolol, animals were killed and BAT was removed, homogenized and centrifuged at 500 g for 10 min at 4 degrees C. The infranatants were incubated during 60 min in the presence of dithiothreitol and 1 microCi [(125)I]T4. Aliquots were chromatographed on paper for the measurement of [(125)I]T4 and its deiodinated subproducts. RESULTS: CGP-12177 restored normal T4 deiodination in SX BAT from both groups, but NE was slightly more effective. Propranolol, although not prazosin, blocked the CGP-12177 effects. Contrariwise, the NE-induced rise in deiodination was blocked by prazosin and to a lesser extent by propranolol. CONCLUSIONS: The results indicate that CGP-12177 stimulated the in vivo activation of 5'-deiodinase type II activity predominantly via beta-3-receptor, without participation of alpha-1-receptors.

["Non-solvent shock agglomeration"--technology of a new alternative method for sustained release of ibuprofen. 5. Production and evaluation of retard formulations]. / Die "Non-solvent shock agglomeration"--Technologie als neuartige alternative Methode zur Aufarbeitung von Ibuprofen. 5. Mitteilung: Herstellung und Beurteilung von retardierten Zubereitungsformen.

Conventional and prepared racemic and optically pure substances were assessed with regard to their suitability to be processed into retarded formulations by direct tabletting. In this respect conventional ibuprofen and specially granulated substances usually show only insufficient properties. Fluid bed granulated S(+)ibuprofen, however, can be suitably transformed into slow release forms by using traditional agents (above all cellulose ether); the low bulk and tapped volume of these granulates, however, is a limiting factor. Shock agglomerated ibuprofen (in particular racemic substance) offers all preconditions of dissolution in acid environment correspondingly prepared substances can cause significant release retardation in artificial intestinal juice. Moreover acceptable tablet qualities (e.g. hardness) can be guaranteed.

["Non-solvent shock agglomeration technology" as a new alternative method for work on ibuprofen. 4. Production and evaluation of quick release forms]. / Die "Non-solvent-shock-agglomeration-Technologie" als neuartige alternative Methode zur Aufarbeitung von Ibuprofen. 4. Mitt.: Herstellung und Beurtellung schnell freisetzender Darreichungsformen.

During compaction of shock-agglomerated S(+)ibuprofen it was of interest if and how far the sometimes strongly differing quality or the origin of the source material has effects on the tabletting properties and on tablet quality. Moreover, conventional and shock agglomerated substances are compared with regard to the parameters mentioned. The technology of "non-solvent shock agglomeration" results in substances suitable for direct tabletting. Additionally, the resulting comprimates have characteristics which can be clearly traced back to the special quality of the ibuprofen-shock agglomerates. By using different agents in the process of substance preparation specific galenic properties can be achieved.

A possible role for acetylcholine in the dialogue between thymocytes and thymic stroma.

In this article we will review data suggesting that acetylcholine takes part in the mutual interplay between developing T cells and thymic epithelium, and thereby may influence the generation of the T-cell repertoire. In the first part we will recapitulate our findings according to which cholinergic agonists affect thymocyte apoptosis via a nicotinergic effect on thymic epithelial cells. In the second part we will present evidence that acetylcholine within the thymus is mainly derived from the thymocytes themselves, and that the production and release of this neurotransmitter is dependent on activation of thymic lymphocytes.

Microencapsulation of chloroquine diphosphate by Eudragit RS100.

Chloroquine diphosphate, a highly water-soluble drug, was encapsulated by using a non-solvent addition coarcevation method. The coating material employed was Eudragit RS100. The liquid manufacturing vehicle was tetrahydrofuran (THF) while the non-solvent liquid was cyclohexane. Polyisobutylene (PIB) was used as an anti-aggregating agent. Particle size as well as shape evaluation was performed. Total drug content, in vitro drug release (from the microcapsules) as well as tasting test experiments were performed. The release studies on the microcapsules revealed an in vitro prolonged release effect while at the same time the bitter taste of the drug appeared to have been considerably masked by this method.

Adrenergic suppression of peripheral blood T cell reactivity in the rat is due to activation of peripheral alpha 2-receptors.

A 20-h treatment of rats with catecholamines using s.c.implantable retard tablets markedly suppresses the in vitro reactivity of peripheral blood (PBL) T lymphocytes, provided that beta-receptors are blocked with propranolol (Felsner et al., 1992). The results can be summarized as follows: (i) the suppressive effect of noradrenaline+propranolol to the concanavalin A (ConA) response of PBL was abolished by the simultaneous application of the alpha-blocker phentolamine. Using selective agonists, the relevant receptor was identified to belong to the alpha 2-subtype. (ii) The alpha-adrenergic suppression of the PBL T cell response was likewise observed in adrenalectomized animals, which rules out the participation of secondarily induced glucocorticoids. Furthermore, the combination of noradrenaline with the watersoluble beta-blocker nadolol was equally effective to suppress the ConA response of PBL. (iii) An analogous alpha-mediated suppression of T cell function of PBL, but not spleen cells, was observed 1 h after i.p. treatment with tyramine, which leads to the release of endogenous noradrenaline. From these results it is concluded that the adrenergic suppression of PBL T cell functions is primarily due to the activation of peripheral alpha 2-receptors and that it is likewise observed under acute indirect sympathomimetic treatment.

Cholinergic stimulation modulates apoptosis and differentiation of murine thymocytes via a nicotinic effect on thymic epithelium.

Effects of cholinergic agonists/antagonists on apoptosis and differentiation of murine thymus cells were investigated in two in vitro models. Treatment with 10(-7) M carbachol was found to counteract the effects of a cortical thymus epithelial cell line (TEC 1.4), on apoptosis and the ratio of CD4 CD8 DP/DN cells in cocultured fetal thymus lobes. A medullary line (TEC 2.3) did not influence apoptosis in fetal thymus lobes. Both TEC lines had the same strong apoptotic effect on thymus cells in suspension, but only the effect of TEC 1.4 was counteracted by carbachol. This cholinergic influence on TEC 1.4 cells is mediated via nicotinic cholinergic receptors, since d-tubocurarine, but not atropine, effectively blocked the effect of carbachol. The results suggest that cholinergic signals to thymic epithelial cells may have regulatory influence on thymic differentiation and selection processes.

Continuous in vivo treatment with catecholamines suppresses in vitro reactivity of rat peripheral blood T-lymphocytes via alpha-mediated mechanisms.

A 20 h continuous treatment of rats with catecholamines, using subcutaneously implantable retard tablets, had either no (adrenaline, isoproterenol, midodrine) or a slight (noradrenaline) suppressive effect on the in vitro responsiveness of peripheral blood T-lymphocytes. A marked suppression of the mitogen response ensued when adrenaline, noradrenaline or midodrine, but not isoproterenol, was applied together with the beta-receptor blocker propranolol, whereas the combination with the alpha-receptor blocker phentolamine had no effect. The mitogen response of splenic lymphocytes was not affected by any of these treatments. This alpha-mediated adrenergic suppression of peripheral blood T-cells was not correlated with general metabolic alterations, shifts in white blood cell counts or CD4+/CD8+ subsets, or with elevated glucocorticoid levels. The data suggest that to consistently influence the reactivity of rat peripheral blood lymphocytes by chronic adrenergic stimuli in vivo requires both high catecholamine levels and a bias towards alpha-adrenergic receptivity.

Isoprenaline cannot act on pancreatic beta cells without hyperglycemia or alpha-block.

During long-term increase in isoprenaline (pronounced beta-effect) and isoprenaline plus regitine (pure beta-effect) pancreatic insulin-secretion still depended mostly on blood glucose levels. This means that increased beta-effect during normo- or hypoglycemia could not cause a higher insulin-secretion. Only during additional alpha-receptor blockade insulin-secretion was slightly but insufficiently increased. Catecholamines seem to be more regulator than originator of the insulin secretory process.

[The use of sustained-release preparations for eye-platelet diagnosis for noninvasive determination of leukocyte migration in the eye]. / Der Einsatz von Liberationsstabilisatoren bei Augendiagnoseplättchen zur unblutigen Messung der Leukozytenmigration am Menschen.

An in vivo method for measuring leukocyte migration in man involves the insertion of membrane filter platelets into the lower conjunctival sac. Before insertion, the filter platelets were soaked in solutions of chemotactic test substances and dried. The chemotactic gradient formed by a dissolving test substance stimulates leukocytes from the conjunctival mucosa to immigrate into a filter platelet. The number and the distribution of immigrant cells within the filter platelet yield information on pathological processes. To obtain reliable results, the chemotactic substance used has to show a defined solubility inherent in only a minority of all substances in question. In order to stabilize liberation, the chemotactic test substance is introduced together with a hydrogel-forming substance into a filter platelet. Among a series of tested hydrogel-forming substances, the Guar derivative Meyprogat 90 proved to have the best stabilizing capacity. For an exact measurement of liberation, a new in vitro model was developed that simulates the conditions of drug liberation within the conjunctival sac. In vitro as well as in vivo tests with this type of filter platelets proved their qualification for human medicine.

The suitability of a combined inulin/PAH retard tablet for measuring renal functions in the conscious rat.

As a further step in the development of implantable retard systems for simultaneous delivery of inulin and PAH, a system based on Eudragit matrix retard tablet has been deviced. It should be able to release a sufficient amount of both substances to maintain constant and well measurable serum and urine concentration in the 36 hours interval between 12-48 hours p.o. The feasibility of the technique was checked by monitoring the behaviour of renal function after administration of a permanent adrenaline application, which we used as a well defined noxa.

Preventive action of phentolamine on adrenaline induced blood glucose elevation in humans.

A comparison of the action of adrenaline infusion and a combined adrenaline + alpha blocker (phentolamine, Regitine) infusion on blood glucose (BG), plasma immunoreactive insulin (IRI), BG/IRI ratio, C-peptide, and plasma cortisol levels was made in healthy young human subjects. The purpose of the experiment was to check, whether alpha block could abolish adrenaline-induced enhancement of blood glucose levels. The results show that during enhanced adrenaline levels, the use of regitine could indeed normalize blood glucose levels, not so much by increasing the IRI secretion, but by diminishing adrenaline-induced liver glycogenolysis via alpha receptors. This could be a model to prevent stress (adrenaline) induced metabolic deviations in diabetics, especially before and during predictable stress situations, e.g. examinations or surgery.

[Development of combined inulin/p-aminohippuric acid (PAH) slow release implantation tablets for clearance determination in awake rats]. / Entwicklung kombinierter Inulin/p-Aminohippursäure (PAH) Retard-Implantationstabletten zur Bestimmung der Clearance an wachen Ratten.

A new method has been developed for the simultaneous measurement of Inulin and PAH clearance in small laboratory animals (rats). An implantable Inulin/p-aminohippuric-acid matrix-retard tablet based on Eudragit was tested with the purpose to estimate renal clearances. Sufficiently high serum and urine levels of both substances can thus be maintained up to 12-48 hours. The advantage of the method is that it can be used for renal clearance tests in small conscious animals, able to move freely within their cages without serious handling stress.

[Fluorodensitometric determination of cytostatic acting Michael-adducts of alpha, beta-unsaturated aldehydes in biologic material]. / Fluorodensitometrische Bestimmung von zytostatisch wirksamen Michael-Addukten alpha, beta-ungesättigter Aldehyde in biologischem Material.

Alpha, beta-unsaturated aldehydes produce a selective cytostatic effect on tumor cells. By the formation of Michael adducts with cysteine, toxicity can be greatly reduced without impairing cytostatic effectiveness. To further enhance the selectivity of the toxic effect, it is necessary to be able to follow the agent's kinetics in the animal body. Among the analytic methods developed to this end, this paper represents the fluorescence derivatisation as a sensitive method for the determination of the Michael adducts of alpha, beta-unsaturated aldehydes in pharmaceutical preparations and in biological material. It is based on the reaction of the carbonyl groups with dansyl hydrazine. Determination is carried out by a combination of thin-layer chromatography with subsequent fluorodensitometric evaluation. The detection limit in blood is about 20 micrograms/ml. The relative standard deviation of this procedure ranges between 3 and 7%.

The effect of adrenaline pretreatment on the in vitro generation of 3,5,3'-triiodothyronine and 3,3',5'-triiodothyronine (reverse T3) in rat liver preparation.

The effects of adrenaline (A) on liver T3 and rT3 neogenesis from T4 were studied in Wistar rats. The animals were implanted subcutaneously either with A or placebo (P) especially coated tablets which linearly released the hormone. The serum A values 6 hrs after implantation of 7.5, 15.0 and 45.0 mg tablets were 6.5 +/- 1.31, 6.8 +/- 1.8 and 16.4 +/- 1.9 ng/ml, respectively vs 4.4 +/- 2.5 ng/ml seen in P pretreated group. The output rates of A were 0.11 (7.5 mg), 0.18 (15 mg) and 0.52 microgram/ml (45 mg). The pretreatment with A led to hyperglycemia and the "low T3 syndrome". Neogenesis of T3 from T4 in medium containing liver microsomes of P pretreated rats was 5.49 +/- 0.25 pmol of T3/mg protein/min and decreased in A pretreated rats to 3.82 +/- 0.17, 3.12 +/- 0.27 and 3.06 +/- 0.11 pmol of T3/mg of protein/min. Neogenesis of rT3 from T4 in microsomes from P group was 1.52 +/- 0.09 pmol rT3/mg protein/min and increased after A to 2.71 +/- 0.11, 2.60 +/- 0.21 and 2.21 +/- 0.34 pmol of rT3/mg protein/min thus showing no dose dependency. Enrichment of microsomes medium with cytosol either from P or A pretreated rats had no effect on T3 generation thus excluding effect of A on cytosolic cofactor. Although cytosol further increased rT3 neogenesis this was seen regardless of whether cytosol was obtained from A or P implanted rats. It is concluded that A decreases the activity of T4-5'-deiodinase in liver, and possibly increases the activity of T4-5-deiodinase.

Functional and morphological changes in the rat kidney after long-term adrenaline application.

A 24 h lasting long term adrenaline application in the form of subcutaneously implanted retard-tablets causes functional and morphological changes in the kidney, which are dose dependent and either reversible or irreversible. Animals in the V 15 group received one 15 mg and in the V 30 group two 15 mg adrenaline tablets resp. The tablets were removed after 24 h and a clearance depot capsule was implanted in the abdominal cavity. The test period extended from 22 h after removal of the retard tabl. to 21 d thereafter. Inulin (except the V 30 grp.), PAH and urea clearance are showing no significant differences. The data of urine gamma-GT activity, urea and urea-N in serum and urine, S-glucose, S-triglycerides, Combur-8-test, Na+ and K+ levels are in normal ranges. Morphological changes were found in the glomerula and tubular regions. Both the number of damaged nephrons and the extent of the damage depend upon the doses of adrenaline given. All glomerula with visible serious changes are irreversibly damaged; this was not true in case of the tubule. In the latter, after 7 d, the fatty deposits had diminished or disappeared.

Vasoconstriction of the vasa afferentia in the rat kidney after long-term adrenaline application.

Adrenaline applied in the form of a retard tablet was implanted subcutaneously under short ether anesthesia under the neck skin of rats. Animals in the V 15 group received one 15 mg adrenaline tablet and those in the V 30 group two 15 mg tablets. The tablets were removed after 24 h. Twenty-two h later plasma catecholamines with the exception of dopamine are elevated in accordance with the amount of adrenaline applied. Histological examination reveals hyalinization of the vasa afferentia and glomerula which is more expressed in the inner part of the renal cortex. Hyalinization begins in the vas afferents and juxtaglomerular cells and extends to the glomerulus. Electron microscopic examination of the vas afferents shows vasoconstriction and beginning cellular degeneration of this vessel. Vasoconstriction is considered to be responsible for the decrease in kidney function.

Peculiar long-term effects of catecholamines and their blockers in rats on insulin, glucose and pancreas.

To be able to study the long-term effects of moderately enhanced catecholamine levels in rats, we developed subcutaneously implantable retard systems, granting a linear output of various agents throughout the test time. Adrenaline application leads to hyperglycemia without elevation of serum immune-reactive-insulin (IRI) during 20 h of uninterrupted adrenaline (A) action. This we call an A-induced diabetes like reaction. It could be completely abolished by simultaneous application of low phentolamine (Regitin) doses. Simultaneous application of propranolol (P) gradually diminished blood glucose levels from about 200 mg/dl after 6 h to 120 mg/dl after 20 h. Since here insulin levels are uniformly low, decline of blood glucose could not be due to enhanced insulin-action. The moderate hyperglycemia after 6 h isoprenaline (ISO)-treatment alone goes with a hyperinsulinemia at the same time. Obviously this hyperinsulinemia cannot cope with the increased blood glucose probably due to enhanced liver-glycogenolysis by intact alpha-action. Later on insulin--despite of beta-action on pancreas--declines strictly proportional with diminishing blood-glucose-levels. A comparison between the action of catecholamines and their blockers showed that alpha-blockers tend to diminish blood glucose levels by two independent ways, namely by the inhibitory action on pancreas and the inhibitory action on liver glycogenolysis.