Showing papers in "Drug Research in 1977"

Evaluation of methods to determine protein-binding of drugs. Equilibrium dialysis, ultrafiltration, ultracentrifugation, gel filtration.

Abstract: The reliability of the most important methods to determine protein-binding of drugs was compared. Applying these methods to different drugs solved in bovine plasma or in protein-free solutions the incidence of errors specific for each method was examined. Certain limits are found for the applicability of each method. If these limitations are observed reproducibility differs only slightly within the four methods. Considering all the results, however, the values achieved by equilibrium dialysis appear to come closest to the real extent of binding.

Mathematical analysis of concentration-response relationships. Method for the evaluation of the ED50 and the number of binding sites per receptor molecule using the logit transformation.

Abstract: The mathematical analysis of concentration-response relationships is performed by means of the mass law and the drug-receptor theory. It is demonstrated that the calculation of the median effective dose (ED50), which is decisive for the pharmacological characterisation of a certain drug, may only be effected by means of the logit transformation. In addition, it is shown that this transformation is most suitable to evaluate in a mathematically simple way the number of drug binding sites of the receptor molecule.

Comparison of the anti-inflammatory activity of Commiphora mukul (an indigenous drug) with those of phenylbutazone and ibuprofen in experimental arthritis induced by mycobacterial adjuvant.

Abstract: In the present investigation a method of induction of experimental arthritis in animals was modified to provide a better model replica of human arthritis. Inflammatory syndrome, resembling rheumatoid arthritis in man, was induced in the right hock joint of albino rabbits by intra-articular injection of the killed mycobacterial adjuvant in liquid paraffin. Development of this arthritic syndrome was studied from a period of five months with and without drugs. Anti-inflammatory agents such as phenylbutazone, ibuprofen and fraction "A" of gum-guggual from Commiphora mukkul were administered orally at a daily dose of 100, 100 and 500 mg/kg, respectively, for a period of five months. All three drugs decreased the thickness of the joint swelling during the course of drug treatment. These results indicate the beneficial role of phenylbutazone, ibuprofen and fraction "A" of gum-guggul in experimental arthritis.

Biological properties and clinical application of propolis. II. Studies on the antiprotozoan activity of ethanol extract of propolis

Abstract: Solutions of the ethanol extract of propolis (EEP) have shown a lethal effect on Trichomonas vaginalis in vitro. Similar lethal action was exhibited by EEP after a 24-h contact with Toxoplasma gondii.

Determination of verapamil in human plasma by mass fragmentography using stable isotope-labelled verapamil as internal standard.

Abstract: In the present investigation a mass fragmentographic procedure for the quantitative determination of verapamil in human plasma was developed which makes use of the principle of mass spectrometry and of isotopic dilution: a known amount of isotopically labelled standard ([13C, 2H2]-verapamil) is added to the plasma sample. After an effective extraction procedure the ratio of the main fragments of verapamil (m/e 303) and the labelled standard (m/e 306) is measured by mass fragmentography. The lower limit of detection is at 1 ng/ml for plasma and at 10 pg/injection for pure verapamil. The precision was found to be between 3.4% and 14.4%, depending on the range (32.7 ng/ml and 2.2 ng/ml, resp.) of the concentration of verapamil in plasma.

Pharmacokinetics and bioavailability of diltiazem (CRD-401) in dog.

Abstract: Pharmacokinetic behaviour of a new coronary vasodilator, the d-cis-isomer of 3-acetoxy-2,3-dihydro-5-[2-(dimethylamino)ethyl]-2-(p-methoxyphenyl)-1,5-benzothiazepin-4(5H)-one hydrochloride (diltiazem, CRD-401), as well as the bioavailability study of the release controlled tablet Herbesser have been described by using the proposed specific assay method of unchanged diltiazem in plasma. Quantitive analysis after its oral administration evidenced that diltiazem was absorbed through the gastrointestinal tract in the intact form. In the kinetical experiment, where diltiazem was administered i.v., a rapid and large distribution of diltiazem into tissue compartment were suggested. In the bioavailability study, a comparison of plasma concentrations of diltiazem between the two different crystals and the micronized powder resulted in no difference in their bioavailability, when they were administered in the form of capsules. In the single and multiple administration of the release controlled tablet, a slow and continuous absorption of diltiazem was observed. Elimination rate after the multiple dose regimen was in good agreement with that in a single dose, thereby indicating no accumulation in the body.

Biological properties and clinical application of propolis. I. Some physico-chemical properties of propolis.

Abstract: The presence of 19 elements has been shown in the ethanol extracts of propolis (EEP). Three fractions have been obtained by filtration through a structural gel that did not show an initial antibacterial activity when investigated separately. Fractions 2 and 3 joined together have regained this activity. EEP solutions maintain their anitbacterial activity in acidic or neutral pH. Insensitivity of EEP solutions on temperautre of 75 degrees C for 30 min has been found.

Haemodynamic effects of a new anti-anginal drug, diltiazem hydrochloride.

Abstract: The haemodynamic effects of a new anti-anginal drug, dilitazem HCl, were studied in 20 patients with angina pectoris. The 131I-dilution method was used. In two patients, one with atrial septal defect and the other with pulmonic regurgitation, heart catheterization was carried out. The drug exerted significant decrease in stroke volume, cardiac output, cardiac work, stroke work and cardiac output/circulating blood volume ratio. The patients who underwent direct cardiac catheterization disclosed no changes in Vmax and ejection fraction, but there were decreases in stroke volume. The decrease in cardiac work and stroke work after after diltiazem Hcl therapy was apparently due to diminution of venous return and prolongation of systemic circulation time. It is postulated that such a decrease leads to inhibition of myocardial oxygen consumption, which in turn has beneficial effects on angina pectoris.

[Effects of intravenous administration of memantine in parkinsonian patients (author's transl)].

Abstract: After a preliminary study in 6 parkinsonian patients concerning the effectiveness and tolerance of 1,3-dimethyl-5-aminoadamantane hydrochloride (memantine) an investigation to assess its short-term effects was performed. In an unselected group of 12 parkinsonian patients 40 mg of memantine diluted in 500 ml of laevulose were applied i.v. within 2 h. The patients were examined under standardized conditions before, immediately after and 2, 4 and 24 h, respectively, using a program of physchological tests. The results give evidence for a favourable influence on rigor and tremor in Parkinson's syndrome as well as on motor drive. In comparative studies memantine showed a better tolerance than adamantylaminosulfate. The short-time effects of the drug could be differentiated from placebo and learning effects.

Influence of central pretreatment with 6-hydroxydopamine on the hypotensive effect of clonidine.

Abstract: Intracisternal (i.ci.) pretreatment of rabbits with 6-hydroxydopamine (6-OH-DA) (3 times 0.5 mg/kg) reduced the norepinephrine content of the brainstem significantly by 52% but did not diminish the hypotensive and bradycardiac action of 2-(2,6-dichloroanilino)-2-imidazoline (clonidine; Catapresan; Catapres) (doses 10, 30 and 100 microgram/kg i.v. and 1 microgram/kg i.ci.) in anaesthetized animals. Pretreatment with 6-OH-DA did not abolish the enhancement by clonidine (100 microgram/kg i.v.) of reflex bradycardia elicited by angiotensin 0.2 microgram/kg i.v. The conclusion is drawn that clonidine acts directly on central alpha-adrenergic receptors independent of storage and synthesis of endogenous catacholamines in the central adrenergic neurons.

Excretion and distribution studies in rats with two forms of 14carbon-labelled polyvinylpyrrolidone with a relatively low mean molecular weight after intravenous administration.

Abstract: Excretion and autoradiographic distribution studies were performed in rats with two 14C-labelled polyvinylpyrrolidone preparations, both of relatively low mean molecular weight but different in molecular weight distribution. At different time intervals after i.v. administration, elimination of radioactivity was found to be more complete for the preparation with the smallest fraction of molecules having a weight of over 25000, which is approximately the weight limit for rapid glomerular filtration in the rat. Our study demonstrates that the retention of PVP in organs, which in the literature are mentioned as target organs for PVP-toxicity, can be largely prevented by decreasing the fraction of molecules with a weight of more than 25000.

Bioavailability from various galenic formulations of flunitrazepam.

Abstract: The absolute and relative bioavailability of flunitrazepam (Rohypnol) tablet, oral solution and suppository formulations was determined in a cross-over study on 6 healthy volunteers. The tablet and the oral solution were shown to be bioequivalent, absorption being at least 80%. For flunitrazepam suppositories the bioavailability was found to be about 50%. The plasma concentrations are described on the basis of a three-compartment model, the adjustment of the curves from the same subject being made simultaneously. The central compartment and the second compartment are about equal in size and rapid exchange takes place between them. The third compartment is about four times as large as the central one. The slow reflux of the compound from the third to the first compartment is the rate determining factor for the overall elimination in the beta-phase.

The pharmacology of N-carbamoyl-2-(2,6-dichlorophenyl)acetamidine hydrochloride (LON-954) a new tremorogenic agent.

Abstract: The tremorogenic properties of a series of benzylimidoylurea derivatives are described. The most potent member, N-carbamoyl-2-(2,6-dichlorophenyl) acetamidine hydrochloride (LON-954), produces a reproducible, dose-dependent rest tremor in the mouse with oral doses of 5-100 mg/kg which is also seen in other species (rat, cat, dog, rabbit). The tremor is of constant frequency, rapid onset and short duration. It is not accompanied by akinesia, muscle ridigity, antinociceptive activity, parasympathomimetic effects or marked hypothermia and in these respects differs from tremor produced by oxotremorine. Pretreatment with a microsomal enzyme inhibitor had no effect on the tremor. An LD50 of 165 mg/kg p.o. was calculated in the mouse. After repeated administration both acute and chronic tolerance developed to the tremorogenic effects of LON-954. Evidence for a central site of action is presented, since the tremor could be reproduced following injection of small quantities (50-100 microgram) into the cerebral ventricles of the mouse. Furthermore, the use of spinal, decorticate and and decerebrate rats indicated that although tremor is not of cortical origin, it arises in an area rostral to the inferior colliculi. The mechanism underlying the tremor appears to involve dopaminergic pathways, since the action of LON-954 was antagonised by L-dopa and apomorphine and potentiated by pimozide. Atropine and carbachol were without effect. It is suggested that LON-954 could be used as an alternative to oxotremorine for the detection of anti-Parkinson drugs, particularly those exerting their effects through dopaminergic mechanisms.

Cardiac action of carazolol and methypranol in comparison with other beta-receptor blockers.

Abstract: The new beta-blockers 4-(2-hydroxy-3-isopropyl-amino-propoxy)-carbazole (carazolol) and 1-(4-acetoxy-2,3,5-trimethylphenyloxy)-3-isopropylamino-propan-2-ol (methypranol, Disorat) were compared with 14 well-known beta-blocking agents with regard to isoproterenol antagonism (equipotent doses in the rabbit i.v.), acute toxicity (LD50 in mice i.v.) and intrinsic sympathomimetic activity (increase in the heart rate of reserpinized rats i.p.). The following descending order for the equipotent beta-receptor blocking doses was obtained: nifenalol, DCI, pronethalol, practolol, sotalol, alprenolol, bupranolol, toliprolol, propranolol, methypranol, YB 2 pindolol, bunitrolol, oxprenolol, bunolol and carazolol. Carazolol had, in addition, the highest therapeutic index and at beta-receptor blocking doses virtually no intrinsic sympathomimetic activity.

Ca2+-transport inhibition by the antitumor agents adriamycin and daunomycin.

Abstract: The antitumor agents adriamycin and daunomycin inhibit Ca2+-transport in mitochondria from Ehrlich ascites carcinoma cells as well as in a biphasic model system. The experimental results indicate that both antibiotics interact with phospholipids. The significance of these observations in the pharmacological behavior of these anticancer compounds is discussed.

Anti-nociceptive substances from the roots of Angelica acutiloba.

Abstract: Anti-nociceptive constituents of the Chinese crude drug Toki (the roots of Angelica acutiloba var. acutiloba Kitagawa) were investigated by means of chemical fractionation and bioassay. Seven active compounds that inhibit AcOH-induced writhing in mice have been isolated from Toki for the first time and identified as falcarinol, falcarindiol, falcarinolone (polyacetylenes), choline, scopoletin, umbelliferone and vanillic acid. Among these, the three polyacetylenes were found to be most active in the writhing test. Falcarindiol and choline also showed anti-nociceptive activities in the retrograde injection test of bradykinin into a carotid artery on rats.

[Model building in pharmacokinetics/Part III: Simplified rules for the deduction of analytical solutions for linear compartment models (author's transl)]

Abstract: Analytical solutions for any linear compartment model are obtained empirically by use of simple rules. Set up of differential equations and tedious integration procedures are thus avoided. The procedure is suited for automation by a calculator. Integrated equations are accessible then even more simply and rapidly.

Effect of zimelidine (H 102/09) in depressive patients.

Abstract: Z-1-(4-Bromophenyl)-1-(3-pyridyl)-3-dimethylaminopropene dihydrochloride hydrate (zimelidine; H 102/09), a newly developed bicyclic substance, was tested in a pilot study for its clinical effect in 10 female patients with a depressive syndrome. Zimelidine inhibits the 5-hydroxytryptamine (5-HT) reuptake more potently than does chlorimipramine. The action on the norepinephrine reuptake is weaker compared with imipramine, also the cardiotoxic and anticholinergic effects are lower. Zimelidine was administered for 20 days in a daily dose of 150 mg. A significant (p less than 0.05) improvement from the beginning of the treatment to the 15th day was demonstrated in Hamilton rating scale and a self-rating scale (von Zerssen). Nevertheless, the zimelidine treatment had to be discontinued between the 15th and 18th days in 3 patients, because of agitation symptoms. The antidepressant action in some patients justifies the performance of controlled studies.

Effects of clozapine and other dibenzo-epines on central dopaminergic and cholinergic systems. Structure-activity relationships.

Abstract: Structure-activity relationships of 16 dibenzoepines, including clozapine, loxapine, clothiapine and perlapine, have been investigated with regard to locomotor inhibition, cataleptogenesis, apomorphine antagonism, arousal inhibition, effect on striatal dopamine metabolism, and in vivo and in vitro anticholinergic potency. Thioridazine and the classical neuroleptics haloperidol and chlorpromazine were included in the study for comparison. The classical tests used to detect neuroleptic activity in laboratory animals were found to be poor predictors of possible clinical effectiveness of the dibenzo-epines.

Antagonizing effect of aspartic acid on the development of physical dependence on and tolerance to morphine in the rat.

Abstract: As free amino acids in the brain have a role in the development of physical dependence on and tolerance to morphine, and in the mechanism of action of some drugs, the effects of aspartic acid which antagonizes some effects of the single dose of morphine were studied during the development of the physical dependence on morphine and after the withdrawal of morphine. 108 rats were given morphine and aspartic acid in different combinations in drinking water for 30 days. Every tenth day the dose of morphine was increased: At the end of this period some of them in each group continued or began to receive aspartic acid depending on the experimental conditions after the withdrawal of morphine. During the experiments body weight, spontaneous motor activity and analgesic threshold were determined. Aspartic acid prevented the alterations induced by morphine during the development of physical dependence and tolerance. Furthermore the rats that received aspartic acid after the withdrawal showed no body weight loss.

Vasotropic drugs--a survey based on a unifying concept of their mechanism of action.

Abstract: A group of vasotropic drugs was surveyed using a new assay method based on the inhibition of endothelaemia increases after a standard vascular lesion in rats. The new test is considerably more sensitive than all previous ones. It provides a common link between all tested vasotropic drugs and points also to their common mechanism of action. All of them have a protective effect on endotherlium based, in some of them at least, on the preservation of the consistency of endothelial cement. The effect is probably mediated by their influence on calcium availability.

[Exchange of aromatically bound halogen for OH- and SCH3-groups in metabolising clozapine in the human organism (author's transl)].

Abstract: 8-Chloro-11-(4-methyl-1-piperazinyl)-5H-dibenzo-(b,e)(1,4)-diazepine (clozapine, 1) is metabolized in humans by exchange of the aromatic halogen for a hydroxy- or a methylthio-group (compounds 2 and 3). Further metabolites are the N-demethyl derivatives of 2 and 3, the compounds 4 and 5. In addition a clozapine metabolite with the structure 6 with an oxidized piperazine ring was found. The presence of a metabolite with an oxidized sulfur atom is suggested. Possible ways for the formation of these metabolites are discussed.

Pharmacokinetic studies with valproic acid in man.

Abstract: A specific gaschromatographic assay for the simultaneous determination of valproic acid (dipropylacetate, DPA) and ethosuximide was developed. In 13 epileptic patients only treated with DPA a significant correlation(r = 0.88; p less than 0.01) between the minimal steady state plasma level of DPA and its dose (mg/kg body weight) was found. Plasma protein binding experiments in 3 healthy volunteers revealed a relatively strong binding of approximately 95%. The pharmacokinetics of DPA was evaluated after a single oral solution of 600 mg in 2 healthy subjects. Absorption was rapid with maximum plasma levels of approximately 70 microng/ml within 1--3 h. DPA was eliminated with a half-life of 7.9 and 10 h. Assuming 100% absorption a total plasma clearance of 10--13 ml/min and an apparent distribution volume of 0.13--0.16 l/kg were calculated. The urinary excretion of unchanged DPA is neglegible (1% of dose). It is suggested that the great fluctuations of the plasma concentrations within a dosing interval may be minimized by special galenic formulations.

Blood levels of the metabolites of glyceryl trinitrate and pentaerythritol tetranitrate after administration of a two-step preparation.

Abstract: Blood levels and urinary excretion rates of glyceryl trinitrate- pentaerythritol tetranitrate, and their less nitrate containing metabolites have been determined in ten human volunteers after a single dose of a two- step preparation containing glyceryl trinitrate and pentaerythritol tetranitrate Blood levels accounted for peak levels of about 40% of the glyceryl trinitrate and 04% of the pentaerythritol tetranitrate metabolites, respectively Within the first 24 h post administration 22% of the glyceryl trinitrate and 19% of the pentaerythritol tetranitrate were excreted as nitrate metabolites, chiefly in form of conjugates The determinations were obtained by gas chromatography on extremely inactive columns and electron capture detection by means of derivatives

Biological properties and clinical application of propolis. VI. Investigation of the influence of ethanol extracts of propolis (EEP) on cartilaginous tissue regeneration.

Abstract: Dressing of artificially formed losses of the cartilaginous tissue with the preparation containing ethanol extract of propolis (EEP) caused acceleration of regenerating processes in the lesioned cartilage EEP inserted into the joint is well tolerated

Experimental blood vascular and lymphatic occlusion in the rabbit ear and the effect of benzopyrones.

Abstract: The effects of lymphostasis and its treatment by a mixture of benzopyrones were studied in the pinnae of rabbit ears. The blood and lymph circulations to the dorsal surfaces of the ears were largely interrupted by excising a portion of skin down to the perichondrium from one edge to the other. The untreated ears became very lymphoedematous, became necrotic and tell off between 7 and 34 days after the operation. The treated ears were much less lymphoedematous, both to the naked eye and by electron microscopy. Owing to the ubiquity of action of the benzopyrones, the phagocytic capacity of the macrophages is enhanced, removing the accumulating protein, the metabolic products and thus the oedematous fluid. This improves the tissue oxygenation, encouraging lymphatic and vascular regeneration and, to a lesser degree, recanalisation. Also, the red blood cells are protected against lactacidotic rigidification and they and the macrophages are given an increased chance of survival in the remaining stagnant areas by the enhancement of glucose up-take and transport. Upon these factors rests the ability of the tissue to survive. The fact that the ears in the treated groups did not fall off, gives a real indication of the potentiality of the benzopyrones.

[Problems of dose finding: sexual hormones (author's transl)].

Abstract: 1. Reproduction processes are differently regulated in different species. The gestagen/estrogen ratio is of paramount importance for the evaluation of gestagens. Steroids possessing inherent estrogenicity might act as estrogens in, e.g., rodents like rats and mice, but might be active as gestagens in women (e.g. norethinodrel). 2. There is a good and partly significant correlation between the activity of various gestagens in a number of experimental test models and clinical trials. The same is true for the antiovulatory activity of various gestagens in rats and women. Oral rat tests, however, are not relevant. Receptor tests are not at all suitable for dose finding. 3. Erroneously dissociated peripheral and central (inhibition of ovulation) activity of gestagens are found only if different animal species are used (e.g., test on gonadotropin inhibition in rats, gestagen test in rabbits). This is not the case if both kinds of tests are done in one species (e.g., ovulation inhibition test in rats and test on the peripheral progestational activity in rats). 4. As far as the combined oral contraceptives containing estrogens and gestagens are concerned, it seems that both components are involved in the inhibition of ovulation in rats and women. There is additive synergism. 5. Conclusions concerning the activity and duration of effect in the clinic can be drawn from the intensity and duration of the progestational effect in rabbits. 6. The oral and subcutaneous activity of estrogens in different tests in rats and mice is in parts very well correlated. This is also true for the antiovulatory activity. 7. Comparison of the estrogenic activity of ethinyl estradiol and mestranol in rats, mice and women still leaves the question unanswered whether ethinyl estradiol is more potent than mestranol. 8. Certain conclusions regarding the depot effect in the clinic can be drawn from the duration of the estrogenic activity in the Allen-Doisy test. This test is at least suitable for the selection of the optimal depot estrogen. 9. As concerns androgens, clinical dose finding is so difficult because there are no or only poor clinical parameters for androgenicity. The oral evaluation of androgens in rats and mice provides no evidence for whether or not an androgen is orally active in men. Frequently, one can only resort to conclusions form analogy. 10. The duration of androgenic activity in rats allows certain conclusions to be drawn regarding the duration of activity in men. Dose finding, however, is difficult. 11. Steroids in which the anabolic and androgenic activity in the levator ani muscle/accessory sexual gland test are dissociated (anabolics) do also show dissociation of these two partial activities in the clinic. 12. The levator ani muscle/accessory sexual gland test in rats allows also conclusions to be drawn as to the depot activity in the clinic. 13...