[Veronal, in Lord Edgware Dies: A Double-edged Sword of Sedation and Addiction]

Veronal, introduced during the early 20th century was widely used as a sleeping pill at the time, and this drug is mentioned in Agatha Christie's novels. Research has proved that in addition to their sedative effects, Veronal and other sleeping pills with similar mechanisms of action are associated with undesirable effects that can lead to addiction and overdose. Barbiturate-induced deaths include the high-profile suicides of the famous American actress Marilyn Monroe and Ryunosuke Akutagawa, a prolific Japanese writer and poet. Soseki Natsume attempted an overdose of sleeping pills; however, he was surrounded by many disciples, and a disciple who observed the adverse effects of the drug prevented Natsume from overdosing. This example highlights that addiction depends on the social relationships surrounding an individual.

Rapid quantification of phenobarbital and barbital in human whole blood by liquid-liquid extraction combined with DART-orbitrap-HRMS

PURPOSE

This study aims to develop and validate a rapid, simple, and efficient bioanalytical method for the simultaneous quantification of phenobarbital and barbital in human whole blood using liquid-liquid extraction combined with direct analysis in real time (DART) and high-resolution mass spectrometry (HRMS).

METHOD

Phenobarbital-d5 and aprobarbital were selected as internal standards (ISs) of phenobarbital and barbital, respectively. A mixed solvent of o-xylene and ethyl acetate at a ratio of 1:6 was used to extract analytes of interest and ISs from 100 μL of human whole blood samples. Phenobarbital and barbital were detected by DART-HRMS. The proposed method has been validated in accordance with United States Food and Drug Administration Guidelines for Bioanalytical Method Validation in terms of selectivity, linearity, accuracy, precision, matrix effect, recovery, stability, and dilution integrity.

RESULTS

The lower limits of quantification (LLOQs) of phenobarbital and barbital were both 10 ng/mL. The linearities were in the range of 10-1000 ng/mL (R² ≥ 0.99). The mean recovery values of phenobarbital and barbital were 99.7% and 88.1%, respectively. The interday and intraday precision values were less than 10.4%, and the interday and intraday accuracy values ranged from 87.6 to 106.7%. Furthermore, the validated method was applied to four cases of phenobarbital poisoning at the Shanghai Institute of Forensic Science.

CONCLUSION

The developed and fully validated method enabled the simultaneous quantification of phenobarbital and barbital in human whole blood and was successfully applied to authentic cases.

Stimulation of tarsal receptors of the blowfly by aliphatic aldehydes and ketones

Rejection of eight aldehydes, eight ketones, five secondary alcohols, and 3-pentanol has been studied in the blowfly Phormia regina Meigen. The data agree with results previously reported for normal alcohols and several series of glycols in showing a logarithmic increase in stimulating effect with increasing chain length. The order of increasing effectiveness among the different species of compounds thus far investigated is the following: polyglycols, diols, secondary alcohols, iso-alcohols, normal alcohols, ketones, iso-aldehydes, normal aldehydes. Curves relating the logarithms of threshold concentration to the logarithms of chain length for diols, alcohols, aldehydes, and ketones show inflections in the 3 to 6 carbon range. Above and below the region of inflection the curves are nearly rectilinear. The slopes for the upper limbs (smaller molecules) are of the order of –2; for the lower limbs, about –10. Comparisons of the threshold data with numerical values for molecular weights, molecular areas and volumes, oil-water distribution coefficients, activity coefficients, standard free energies, vapor pressures, boiling points, melting points, dipole moments, dielectric constants, and degree of association are discussed briefly, and it is concluded that none of the comparisons serves to bring the data from the several series and from the two portions of each series into a single homogeneous system. A qualitative comparison with water solubilities shows fewer discrepancies. It is suggested that the existence of a combination of aqueous and lipoid phases at the receptor surface would fit best with what is presently known about the relationship between chemical structure and stimulating effect in contact chemoreception. In this hypothesis the smaller and more highly water-soluble compounds are envisaged as gaining access to the receptors partly through the aqueous phase, the larger molecules predominantly through the lipoid phase.

[Crystallographic characteristics of crystal habits and their peculiarity to the substance (study of crystalline drugs by mesns of a polarizing microscope. XVIII)]

Crystallographic and optical characteristics of crystal habits have been investigated comparing the both results of goniometric and newly developed polarizing microscopic methods. It has been found that the predominant faces of crystal habits are mostly formed by (001) or (100) of orthorhombic or monoclinic system and (010) of monoclinic system, and a little part by triclinic (001). Not so many numbers of predominant faces were found to be formed by orthorhombic or monoclinic (110) making prismatic habits. Key refractive indices have been found to be uniquely measured from those habits, and it was also found that one or two of them were coincided with the principal refractive indexes, which will become important facts for the analytical use of crystal habits.

In vitro testing of bioprostheses: influence of mechanical stresses and lipids on calcification

BACKGROUND

Structural valve deterioration of bioprostheses is mainly caused by the progressive development of calcification. Mechanical stresses or lipid deposits in porcine aortic leaflets have been proposed as major factors contributing to the calcification process.

METHODS

A new test protocol consisting of nondestructive holographic interferometry, which allows a quantitative deformation analysis of heart valves, and accelerated dynamic in vitro calcification was used. The rapid calcification fluid contained a final combined calcium and phosphorus concentration of 130 (mg/dL)2 in barbital buffer solution. The calcification of 32 bioprostheses donated by different manufacturers (SJM Bioimplant, Biocor standard, Biocor No-React, Carpentier-Edwards SAV, Bravo, pericardial prototype) was assessed after up to 25 x 10(6) cycles by microradiography and the areas of calcification were compared with the holographic interferograms. The distribution of lipid droplets of four porcine prostheses were visualized by Sudan III stain before the calcification process.

RESULTS

Most of the tested bioprostheses had areas presenting with stress concentrations, and the dynamic in vitro testing resulted in leaflet calcification corresponding to the holographic irregularities. A strong correlation between calcification and stress distribution or lipid accumulation was found (r = 0.72; r = 0.81, respectively). After 19 x 10(6) cycles, the Carpentier-Edwards SAV and the pericardial valves had significantly less calcification than other prostheses tested (p = 0.003), but the variation among individual prostheses from the same manufacturer was even more pronounced.

CONCLUSIONS

Mechanical stresses or lipid accumulation seems to play an important role in the calcification process of bioprostheses. Quality control of bioprosthetic valves using holographic interferometry has the potential to predict calcification before implantation.

An ATP-sensitive potassium (KATP) channel opener, nicorandil, lowers the threshold for ischemic preconditioning in barbital-anesthetized dogs

To determine whether the adenosine triphosphate (ATP)-sensitive potassium channel (KATP channel) opener, nicorandil, lowers the threshold for the infarct-reducing effect of preconditioning (PC), barbital-anesthetized dogs were subjected to 60-min occlusion (60'OC) of left anterior descending coronary artery (LAD) followed by 3-h reperfusion (3h-RP). At the end of the 3h-RP, heart was resected to measure infarct size. Infarct size was determined by triphenyltetrazolium chloride (TTC) staining, calculated gravimetrically and was expressed as a percent age of area at risk (AAR). Myocardial blood flow was measured by radioactive microspheres. Single 5-min LAD occlusion 10 min before 60'OC (5'PC group) markedly reduced infarct size, compared to the controls (11.8 +/- 3.7% versus 26.8 +/- 4.7%; P < 0.05). Neither 2.5-min PC (2.5'PC group), nor 2.5-min intracoronary infusion with 0.5 microgram/kg per min of nicorandil followed by a 10-min drug-free period (2.5'NC group), showed a cardioprotective effect (26.5 +/- 1.7% and 20.7 +/- 2.8%, respectively). However, when nicorandil was administered during the 2.5-min LAD occlusion period (2.5'PC + 2.5'NC group), infarct size was significantly reduced to an extent similar to that in 5'PC group (13.6 +/- 1.2%). There were no significant differences in hemodynamics, collateral circulation, or AAR between groups. These results suggest that nicorandil lowers the threshold for the infarct-reducing effect of PC in dogs by, at least in part, activation of myocardial KATP channels.

METABOLISM OF BARBITAL BY STREPTOMYCES MEDITERRANEI

The metabolism of barbital in cultures of Streptomyces mediterranei was studied. Small quantities were transformed during the fermentation. Four compounds were isolated and identified as 5-ethyldialuric acid, 5-ethylbarbituric acid, 5-(beta-hydroxyethyl)-5-ethylbarbituric acid, and diethylmalonic acid monoureid. The influence of these compounds on the production of rifamycin was of minor importance. With the aid of C(14)-barbital, it was established that neither barbital nor any of its metabolic products can be considered as precursors of the rifamycin B.

Effects of nifedipine on physical dependence on barbital or diazepam in rats

The effects of nifedipine on the development of physical dependence on barbital and diazepam in rats were examined using the drug-admixed food method. Rats were chronically treated with either barbital- or barbital in combination with nifedipine-admixed food for 28 days, and with either diazepam- or diazepam in combination with nifedipine-admixed food for 26 days, on schedules of gradually increasing doses of barbital or diazepam. Withdrawal was conducted by substituting normal food for drug-admixed food on the last day of the treatment. Co-administration of nifedipine with barbital potentiated weight loss and withdrawal scores after the termination of barbital treatment. However, the withdrawal signs after the termination of diazepam treatment were not affected by co-administration of nifedipine with diazepam. These results suggest that nifedipine potentiates the development of physical dependence on barbital but not diazepam. It is known that co-administration of dihydropyridine derivative nitrendipine suppresses the development of physical dependence on ethanol. Basing on the differences in sensitivity of central depressants, barbiturates, benzodiazepines and ethanol, to three types of voltage-dependent Ca2+ channels, such as L-, N- and T-types studied so far, the development of physical dependence on central depressants may be modified differently by L-type Ca2+ channel blockers, corresponding to respective depressants.

Elimination of the antianalgesic action of dynorphin A by spinal transsection in barbital-anesthetized mice

Previous studies in mice demonstrate that, when dynorphin A (1-17) (Dyn A) is administered intrathecally (i.t.) or released spinally (by administration of clonidine or midazolam i.c.v.), i.t. morphine-induced analgesia was reduced. The present aim was to determine whether this antianalgesic action of Dyn A was the result of a spinal or supraspinal site of action by performing studies in spinally transsected mice. The approach was to use anesthetized, acute spinally transsected mice rather than chronic spinally transsected animals to avoid the need for long-term special animal care. The first part of the study evaluated four nonvolatile general anesthetic agents in an attempt to obtain one that did not affect the antianalgesic action of Dyn A, the release of Dyn A, the analgesic action of i.t. morphine (inhibition of the tail-flick response) or the tail-flick latency by itself. alpha-Chloralose (120 mg/kg), urethane (1 g/kg) and pentobarbital (20 or 40 mg/kg) given i.p. did not meet one or more of these requirements. Barbital 400 mg/kg i.p. met the requirements. In the second part of the study, barbital combined with halothane anesthesia was used to perform acute spinal transsection experiments. As in sham controls, the analgesic action of i.t. morphine was undiminished in spinally transsected animals, which indicated that the inhibition of the tail-flick response produced by i.t. morphine was on a spinal reflex response. On the other hand, spinal transsection produced a loss of the action of i.t. Dyn A to antagonize i.t. morphine-induced analgesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum factor(s) induced by restraint stress in mice and rats suppresses lymphocyte proliferation

LACA mice were individually restrained in a specially made cylindrical cage for 10-20 h at room temperature (20 degrees C). Serum obtained from stressed mice was found to suppress normal mouse lymphocyte proliferation induced by concanavalin A, suggesting the presence of a suppressive factor(s) in the stressed serum. Adrenalectomy or injections of naltrexone (1, 10, or 20 mg/kg, ip), just prior to and in the middle of the stress period, did not affect the suppressive activity of serum from mice. However, the suppressive activity was totally abolished by general anesthesia with urethane (1.5 g/kg, ip). These results suggest that adrenal hormones and opiate receptors are not involved in the generation of the suppressive factor(s) and that the central nervous system plays a very important role in this process. SD rats were restrained in a supine position for 20 h at room temperature (20 degrees C) and serum from stressed rats was also found to be able to suppress normal mouse lymphocyte proliferation. A further analysis of "stressed serum" indicated that the suppressive factor(s) was heat stable (56 degrees C, 30 min) and acid stable (pH 3.8), but sensitive to 100 degrees C (3 min), an organic solvent (greater than 60% methanol), and proteinases (trypsin and chymotrypsin). From the measurement of gel filtration (HPLC), the molecular weights of the suppressive factor(s) were 155 and 370 kDa. Taken together, these results indicate that the suppressive factor(s) is a protein with a large molecular weight.

Characterization of an adhesion antigen of Streptococcus sanguis G9B

An antigen possessing the attributes of an adhesion has been identified in Streptococcus sanguis G9B. Cell surface components were extracted from G9B and a spontaneously occurring nonadherent mutant of G9B, strain Adh-, with a 2 mM barbital buffer, pH 8.6. The extract of G9B but not of Adh- absorbed more than 80% of the adhesion-inhibitory activity of anti-G9B immunoglobulin G (IgG). Immunoblots revealed 80- and 52-kilodalton (kDa) antigens present in the G9B extract but not in the Adh- extract. Absorption of anti-G9B IgG with Adh- and G9B barbital extracts showed a correlation between the loss of the 80- and 52-kDa antibodies and the loss of adhesion-inhibitory activity. An antibody prepared against the 80-kDa antigen excised from sodium dodecyl sulfate-polyacrylamide gels recognized the 80- and 52-kDa antigens and another antigen of 62 kDa but did not inhibit adhesion. However, an antibody from an electroblot containing the native protein from which the 80-kDa and related antigens were derived (the 80-kDa antigen complex) inhibited adhesion to the same extent as anti-G9B IgG. Periodate oxidation of the G9B barbital extract modified the 80-kDa antigen complex and resulted in the loss of 40% of its absorbing activity. The barbital extract also contained an endogenous enzyme responsible for producing the 62- and 52-kDa antigens from the 80-kDa protein and which, under optimal conditions, degraded the antigen completely, resulting in the loss of antibody-absorbing activity. The 80-kDa antigen complex has a molecular mass of more than 200 kDa in native polyacrylamide gels and a pI of 4.1 to 4.8. These observations suggest that the adhesion antigen in S. sanguis G9B is a large glycoprotein from which an 80-kDa antigen complex is derived.

Streptococcus sanguis surface antigens and their interactions with saliva

Saliva-binding molecules of Streptococcus sanguis and their receptors were investigated. Streptococcal cell surfaces were extracted with a barbital buffer and examined immunochemically. Strains G9B and Blackburn, which adhere specifically to saliva-coated hydroxyapatite via immunologically related adhesins, possess 80-, 62-, and 52-kilodalton (kDa), and 52-, 42-, and 29-kDa polypeptides, respectively, which correlate with adhesion to saliva-coated hydroxyapatite. Nonadherent strains Adh- and M-5 lack these antigens. In an immunoblot overlay, the putative adhesins bound to a 73-kDa receptor present in submandibular saliva but not in parotid saliva. G9B also contains a 160-kDa surface protein which bound to an unidentified receptor in both submandibular and parotid saliva samples. Blackburn barbital-extracted components bound to 78- and 70-kDa receptors in parotid saliva. These bacterial-salivary interactions may be important in the regulation of oral ecology.

Induction of alkoxyresorufin O-dealkylases, epoxide hydrolase, and liver weight gain: correlation with liver tumor-promoting potential in a series of barbiturates

The effects of a series of barbiturates, of known and varying liver tumor-promoting ability, on several short-term endpoints including liver weight and liver-to-body weight ratio increases and induction of cytochromes(s) P-450 and epoxide hydrolase activities were examined. Male F344 rats (3 months of age) were administered barbiturates in the drinking water for 12 days. At the end of the treatment period they were killed, body and liver weights were taken, microsomal p-nitroanisole O-demethylation and epoxide hydration, and liver S-9 O-dealkylation of ethoxy-, pentoxy- and benzyloxyresorufin were measured. The latter two substrates have been shown to be preferentially metabolized by the major phenobarbital-inducible form of cytochrome(s) P-450 (P-450b), and were employed since they offered a means of differentiating more clearly varying levels of P-450 induction. Exposure to sodium barbital (SB) and sodium phenobarbital (PB) resulted in significant increases in liver weight and liver-to-body weight ratios. Induction of cytochrome(s) P-450 and epoxide hydrolase activities by the various barbiturates depended on the functional groups on C5. When ranked in terms of decreasing induction potency, the following order was obtained for each enzyme activity quantitated: PB, SB, sodium pentobarbital, amobarbital, hexobarbital and the C5-unsubstituted parent compound (barbituric acid). Thus, the barbiturates were found to exhibit a spectrum of induction potencies, with PB and SB, the most potent liver tumor promoters, yielding the greatest degree of liver weight increase and induction of cytochrome(s) P-450 and epoxide hydrolase activities.

[Sex differences in the physical dependence on barbital in rats]

Sex differences in physical dependence on barbital (BAR), which is not readily metabolized in rats, were studied by the drug-admixed food method. The concentration of BAR in the food was gradually increased from 1 and 2 up to 6 and 8 mg/g food concurrently available to each rat over a period of 36 days in both male and female Sprague-Dawley rats. Sedation and muscle relaxation were observed in males at the 4 and 6 mg/g condition and to a greater degree at 6 and 8 mg/g of food. This effect was seen only at the highest drug concentration, 6 and 8 mg/g food, in females. Physical dependence was assessed in both sexes after substitution of normal food for the BAR-admixed food. Various signs of BAR withdrawal were observed including vocalization, irritability, muscle rigidity, tremors and convulsions. The incidence of convulsions was 76.9% in females and 45.5% in males, respectively. Maximum weight loss was 15.4% in females and 12.1% in males. However, brain BAR concentrations in the male rats were higher than that in the female rats 9 hours before onset of withdrawal and at all later time points tested. Thus, we have demonstrated that weak sex differences in physical dependence on BAR exist and suggest that this difference resulted from a difference in CNS sensitivity to BAR.

Differences in cardiovascular responses to peripherally administered GABA as influenced by basal conditions and type of anaesthesia

The cardiovascular (blood pressure, heart rate, cardiac contractility) effects of i.v. gamma-aminobutyric acid (GABA) were investigated in guinea-pigs anaesthetized with barbitone or urethane. GABA (0.1-10 mg kg-1) produced a transient 'depressive' effect on cardiovascular parameters which in barbitone-anaesthetized animals was followed by a transient 'excitatory' effect. Resting cardiovascular parameters were higher in urethane-as compared to barbitone-anaesthetized animals. Picrotoxin pretreatment (2 mg kg-1, i.v.) barely affected the cardiovascular changes produced by GABA in barbitone-anaesthetized animals. In picrotoxin pretreated animals anaesthetized with urethane, GABA produced an initial depression of cardiovascular parameters followed by an excitatory phase. Hexamethonium (20 mg kg-1, i.v.) suppressed or reduced markedly the GABA-induced cardiovascular changes both in barbitone- or urethane- anaesthetized animals. Reserpine pretreatment lowered resting cardiovascular parameters. In these animals, regardless of type of anaesthesia, the effects of i.v. GABA were of the 'excitatory' type only. Reserpine pretreated animals anaesthetized with barbitone were selected for further experiments. Various GABAA receptor agonists (homotaurine, muscimol, THIP, 5-aminovaleric acid) mimicked the 'excitatory' effect of GABA in reserpine pretreated animals anesthetized with barbitone and prevented the effects of subsequent GABA administration. On the other hand (+/-)-baclofen, a selective GABAB receptor agonist, had a slight depressant effect and did not prevent the 'excitatory' cardiovascular effects of GABA. Neither bicuculline nor picrotoxin pretreatment prevented the 'excitatory' cardiovascular effect of i.v. GABA in reserpine pretreated, guinea-pigs anaesthetized with barbitone. In adrenalectomized guinea-pigs or in preparations receiving i.v. phentolamine plus propranolol, GABA produced only a small 'depressant' effect on cardiovascular parameters. These findings demonstrate that GABA exerts a neuromodulatory effect on cardiovascular function via peripheral actions which is influenced by: type of anaesthesia resting values of cardiovascular parameters degree of activity of the sympathetic nervous system and catecholamine release from the adrenal medulla.

The effect of method of infection on the pathway of juvenile Strongyloides ratti in the host

Subcutaneous injection of the larvae is the almost universally adopted means of initiating experimental infections of skin-invading roundworms but, so far, the possibility that this procedure introduces artefacts of one kind or another has not been critically studied. Experiments described in this paper were used to compare the effect of (a) injection and (b) skin application, of a small, precisely counted ('exact') dose of larvae. Results with two strains of S. ratti showed that the same proportion of the dose developed to adults in the intestines of rats irrespective of the method. With the same exact dose technique it has been shown that milk-borne infection of the pups of lactating rats is not an artefact produced by injection. Large doses (mean 4000) of larvae of the homogonic strain of S. ratti carrying a radioactive label of 75Se were tracked in their migration to the mammary gland following injection or skin application at two different sites on the right-hand side of nursing mother rats. The broad conclusion of earlier work in this laboratory using injection, that larvae move by a local route and not a systemic one, was supported by the results. The detailed distribution of the label and of unlabelled worms of the heterogonic strain in families was, however, different for the two methods, indicating that subtle variations in pathway can be brought about by the use of injection. If migration involves the lymphatic system, then the interpretation of immunological experiments in terms of lymphatic anatomy must take account of such procedural effects. The extent to which these results contribute to theories of migration in Strongyloides ratti is discussed.

Studies on the development of physical dependence on barbitone in the rat and rat atrium

The mechanisms underlying the development of barbitone dependence have been studied in the rat and in atrial preparations removed from dependent animals. Long-term oral administration to the rat of barbitone, alone or together with the analeptics bemegride or pentylenetetrazol, has shown that the intensity of the withdrawal syndrome generally parallels the degree of associated CNS depression. In addition, the overall relationship between the spontaneous or evoked (chemical or audiogenic) responses of representative drug-withdrawn rats and the inotropic responses of corresponding withdrawn atria to supramaximal nerve stimulation, noradrenaline or Ca2+ was reasonably good. It is proposed that the rat atrial preparation may provide a suitable model system for the study of barbitone dependence in the rat, especially in relation to Ca2+-dependent mechanisms, and that selective calcium antagonists may prove helpful in the management of barbiturate and similar types of drug dependence. The barbitone withdrawal syndrome has been described in terms of a membrane phase distribution hypothesis of drug action.

Study of discrepancies in rubella haemagglutinin titrations and a reappraisal of diluents used in the rubella haemagglutination inhibition technique

To elucidate inconsistencies in rubella haemagglutinin assays the components of the assay technique were examined. The results of carefully controlled assays of rubella haemagglutinin antigens from different sources in various plates and diluents with four species of indicator cells are reported. The quality and quantity of gelatin in the dextrose-gelatin-veronal buffered diluent commonly used in rubella haemagglutinin assays had a profound effect on the haemagglutination pattern and antigen titre. The veronal buffered saline used in the complement fixation test offered a valid alternative to the more complex diluents incorporating gelatin currently used in rubella haemagglutinin assays and haemagglutination inhibition tests.

Counter current immunoelectrophoresis, a new technique for the rapid serodiagnosis of porcine cysticercosis

Counter current immunoelectrophoresis was used to detect porcine cysticercosis and water soluble extracts of scolex and of scolex with cyst wall were used as antigens. Serum samples from 40 pigs infected with Cysticercus cellulosae, five infected with C. tenuicollis and five with hydatid cysts, and 15 healthy pigs were tested. A sharp and thick concave precipitin band was observed at the point of interaction of antigen and antibody within 90 min in 39 sera from infected pigs (97.5%). The precipitin reaction was better in barbitone buffer of pH 8.6 with the well distance at 6 mm. No false or cross reaction were found and the test was rapid and sensitive.

The influence of haloperidol and aminooxyacetic acid on etonitazene, alcohol, diazepam and barbital consumption

Four groups of rats were given free choice between water and solutions of either 3 micrograms/ml etonitazene, 5% ethanol (v/v), 0.1 mg/ml diazepam or 3 mg/ml barbital for 10-14 days. With the exception of barbital, some rats spontaneously preferred the drug solutions to water. This preference was reduced by addition of 7 micrograms/ml haolperidol. In a forced drug fluid consumption procedure, the daily administration of 15 mg/kg i.p. of the gamma-aminobutyric acid (GABA)-transaminase blocker aminooxyacetic acid (AOAA) led to a reduction of ethanol and diazepam intake, but not of etonitazene and barbital. It is suggested that the diminished consumption of ethanol and diazepam as caused by GABA-T-inhibition may also be mediated by dopamine which seems to act indirectly, via benzodiazepine receptors and GABA neurons.

Influence of drug partition coefficient and pH value of sink solution on permeation from porous thick-walled ethyl cellulose microcapsules

The permeation of barbitone sodium, benzoic acid, and salicylic acid from microcapsules into aqueous medium has been examined at different pH values. The apparent diffusion coefficients of drugs were linearly proportional to the ethyl cellulose/water partition coefficient of drugs, and the straight line parameters were dependent upon volume fractions of water-filled pores (i.e. capsule size), testifying to a previously proposed mechanism of drug permeation. The rate of drug permeation was also a function of the pH-value of the surrounding sink solution; the period of zero order release was longer at low pH because of the change of drug partition or solubility or both.

Biochemical aspects in the experimental barbital dependence IV--its effect on the hexokinase and phosphofructokinase activities in the rat brain

Effects of barbital dosing on the neural hexokinase (EC 2.7.1.1) and phosphofructokinase (EC 2.7.2.11) activities in the rat, were examined. The barbital dependence in the rat was acquired by giving the barbital-admixed food. These two enzyme activities were investigated in the following three dissected portions of the brain: cerebral cortex, brain stem and cerebellum. The both enzyme activities in these three portions were depressed by the barbital dosing, while them being increased at the early stage of its withdrawal. From these results, it is considered that the measurements of hexokinase and phosphofructokinase activities probably give a possibility to estimate the degree of barbital dependence and its withdrawal, and that these two enzyme activities can be good indices in these conditions.

Direct preparation of solid particulates of aminopyrine-barbital complex (pyrabital) from droplets by a spray-drying technique

Aqueous slurries of aminopyrine and barbital (molecular ratio 2:1) containing various excipients such as colloidal silica, synthetic aluminum silicate, montmorillonite clay, corn starch, microcrystalline cellulose, hydroxypropylcellulose, methylcellulose, gelatin, and chitosan were spray-dried by a centrifugal wheel atomizer with various rotation speeds (10,000-40,000 rpm) at various temperatures (85-145 +/- 5 degrees). The spray-dried products were a mixture of aminopyrine-barbital complex (molecular ratio 1:1), aminopyrine, and the excipient used. The flowability and the packing property of the products were improved by compounding colloidal silica into the formulation used for spray-drying. The products with montmorillonite clay, chitosan, and a corn starch-colloidal silica mixture were compressed directly into tablets. It was found that aminopyrine in the products was oxidized during spray-drying. The oxidation products were assumed to be a trace mixture of 5-oxo-2-methyl-4-dimethylamino-1-phenyl-3-pyrazoline carboxyaldehyde and miscellaneous oxidation products. Montmorillonite clay compounded in the formulation considerably prevented the oxidation of aminopyrine during spray-drying. The present study proposes an improved method for the preparation of solid particulates of aminopyrine-barbital complex for tableting, which combines the synthesis, drying, and agglomeration processes into a single process.

Formation of physical dependence on barbiturates and cerebral monoamines

The effects of cerebral monoamine-related substances during the course of formation of barbital (B) dependence were studied in male S.D. rats by the B-admixed food method. The monoamine-related substances, p-chlorophenylalanine (PCPA), tranylcypromine (Tcp), alpha-methyl-p-tyrosine (alpha-MT), methamphetamine (MA) and reserpine were administered during each B treatment period, except in the control group that was fed a food admixed with B only. All groups were examined for B withdrawal signs during each of 2 B withdrawal periods. Compared with the control group, B withdrawal signs tended to be mild in the PCPA-treated group, remained similar in the Tcp-treated group, were severe in the alpha-MT-treated group, very mild in the MA-treated group, and very severe in the reserpine-treated group. These findings suggested B withdrawal signs may tend to be reduced in severity if the activity of catecholaminergic neurons is kept elevated during the course of formation of physical dependence on B, and they suggested that acquisition of tolerance to and formation of dependence on barbiturates tend to be reduced under a condition of reduced cerebral 5-HT activity.

Biochemical aspects of experimental barbital dependence II: Effect on glycometabolism

A single injection of barbital increased glycogen, while it decreased glucose and glucose-6-phosphate levels in the rat brain. In long barbital dosing (36 days), however, the metabolite level of carbohydrate was almost recovered to the non-treated level. At the later stage of withdrawal (24-48 hr), all metabolites examined except lactate decreased. Only lactate increased remarkably. The effect of barbital dosing and withdrawal was almost same in the three portions, i.e., the cerebral cortex, brain stem, and cerebellum. Barbital depresses the central glycometabolism, and at the dependent stage (long term barbital dosing, 36 days or more), metabolism was almost same as the control. At the later period of withdrawal, it appeared that lactate was increased because of the hypoxic condition caused by stroke. In conclusion, carbohydrate metabolism can probably serve as a sensitive measure for the development of barbital dependence and the onset of withdrawal.

Biochemical aspects of experimental barbital dependence III: effect on neural energy reserve system

The effect of barbital intoxication on the neural energy reserve of rat was examined. The energy metabolism was depressed at dependent developing stage and recover to the non treated level at dependent stage. After withdrawal, rapid degradation of creatine phosphate and adenosine triphosphate was recognized. Later stage of withdrawal, the sum of creatine phosphate and adenosine triphosphate was decreased, and adenosine diphosphate and adenosine monophosphate was remarkably increased. These changes in neural energy reserve were parallel to the changes in adenylate cyclase activity and carbohydrate metabolism which were previously presented. These changes may have possible role in development of drug dependence and or withdrawal.

"Superactive" charcoal adsorbs drugs as fast as standard antidotal charcoal

Experimental data on the uptake of two test drugs by powdered Amoco PX-21 and Norit A activated charcoals in stirred-batch tests indicate that the rate of uptake by the Amoco charcoal is equal to, or higher than, the uptake rate by Norit A. In contrast to the conjecture of Medema [1], the superactive Amoco charcoal is not kinetically inferior to Norit A. The superactive charcoal remains highly recommended for antidotal uses.

Surface activities of barbital, phenobarbital, and pentobarbital and their interaction energies with phospholipid monolayers

The adsorption free energies of barbital, phenobarbital, and pentobarbital at the air-water interface were estimated from plots of the surface pressure (pi less than or equal to 5 dynes/cm) against the bulk concentration. Their energies of interaction with dipalmitoylphosphatidylethanolamine and dipalmitoyllecithin monolayers spread at the air-water interface were estimated from the surface pressure increase with increasing concentrations of the subphase-injected barbituric acid derivatives. Adsorption free energies and interaction energies were barbital less than phenobarbital less than pentobarbital, which correlate with their nerve blocking concentration.

[On the Polymorphism of barbiturates in powders and tablets. Part 4: the dissolution of barbital B and barbital A (modifications I and III and their release from tablets (author's transl)]

Two commercial brands of barbital (A: German Democratic Republic, modification III; B: Hungarian Peopl's Republic, modification I) were used to study the solubility and dissolution of the modifications. Crystals of these two substances were brought into the shape of tablets, the physical parameters and textural properties of which were determined. The effect of polymorphism on the release of these substances is discussed in the light of the results obtained from this investigation. The discussion will be continued and summarized in a subsequent paper, including further modifications.

Drug dependence potential of viloxazine hydrochloride tested in rhesus monkeys

The drug dependence potential of viloxazine was tested in 5 experiments on rhesus monkeys. In gross behavioral observation of normal monkeys the acute CNS effects of the drug were found to be very weak. Decrement of spontaneous motor activity and occasional eye-closing were observed with single doses higher than 16 mg/kg IV, IM and 128 mg/kg PO, while convulsions and death occured at 64 mg/kg IV and IM. Viloxazine did not suppress the morphine and barbital withdrawal signs in monkeys that had been made physically dependent on these drugs and withdrawal. In the test for physical dependence by repeated administration of the drug at 16 mg/kg IM twice daily for 31 days in normal monkeys, no observable withdrawal sign was developed in the naloxone precipitation and natural withdrawal tests. In intravenous self-administration experiments, a weak reinforcing effect was demonstrated in some monkeys, but the effect was extremely weak. Thus, viloxazine was found to be physical dependence-free and its overall dependence potential was regarded as very low.

[On the polymorphism of barbiturates in powders and tablets - Part 3: The effect of the pressing power on the modification of barbital (author's transl)]

The authors took X-ray diffraction pictures from two commercial brands of barbital (produced in the GDR and in the Hungarian People's Republic, respectively), the interpretation of which convinced them that these two commercial brands are different modifications. These crystals were brought by pressure (10 and 20 kN) into the shape of tablets. Textural studies showed that both commercial brands are easy to compress. An increase in pressing power caused insignificant changes in the structure of the GDR product; and in the Hungarian commercial product, only slight changes were observed. It could be proved by X-ray diffraction analysis that the form of the barbital crystals is affected by the application of pressure. But this change occurs already under a pressure less than 10 kN. A further increase in pressing power produces no further changes in crystal structure.

Crystal structure of 1:1 complex of barbital with 1-methylimidazole

The prediction of a strong hydrogen-bonding interaction between barbital and 1-methylimidazole was confirmed. Two crystal complexes were obtained, 1:1 and 2:1, and the X-ray structure was determined for the 1:1 complex, which is monoclinic, space group P21/c, with a = 12.236(3) A, b = 11.332(4) A, c = 12.495(4) A, and beta = 120.67(1) degrees. The structure contains disk-shaped hydrogen-bonded tetramers with two molecules of each kind. There is a short NH...N hydrogen bond (2.82 A) in which barbiturate provides the NH donor.

Mechanism of fluorometric analysis of tetracycline involving metal complexation

Tetracycline complexation with calcium and organic ligands was studied using fluorescence, circular dichroism, and solvent extraction methods. The results were used to interpret the mechanism of the commonly used fluorometric methods for the analysis of tetracycline in biological fluids. Tetracycline formed ternary calcium complexes with barbital sodium and L-tryptophan in alkaline solutions. The circular dichroism studies indicate that the calcium ion in these complexes is bound to the C-4 dimethylamino and the C-12a hydroxyl groups of tetracycline. These ternary complexes are strongly fluorescent and can be extracted easily into 1-butanol or ethyl acetate. Based on the characteristics of the ternary complexes and of the tetracycline degradation products, it is concluded that only the active form of tetracycline can be complexed and extracted for fluorescence analysis.

A non-barbital buffer for immunoelectrophoresis and zone electrophoresis in agarose gels

We describe buffer for both immunoelectrophoresis and zone electrophoresis procedures in agarose gels, Tricine [N-tris(hydroxymethyl)methylglycine] and Tris [2-amino-2-(hydroxymethyl)-1,3-propanediol] being the main components. This buffer eliminates the procurement cost and inventory control associated with formulation of barbital buffers. We compare it with other common buffer formulations.

Comparative studies of hemoperfusion devices. I. In vitro clearance characteristics

Drug adsorption studies were carried out using three charcoal-based and one resin-based hemoperfusion devices. They were the Sandev Hemocol unit, the Gambro Adsorba 300C unit unit, the Becton-Dickinson Hemodetoxifier, and the Extracorporeal Medical Specialties XR-010 Hemoperfusion column, respectively. Clearance versus time tests of up to six hours duration were performed using solutions of sodium salicylate, sodium barbital, and creatinine in a pH 7.4 buffer which were pumped through the columns at flow rates of either 100 or 200 ml/minute. Short term clearance tests were performed at various other flow rates to determine overall mass transfer resistances for the devices. Further analysis yielded values for the individual fluid-phase and solid-phase resistances. Studies were also done using sodium salicylate in bovine blood. The results provide information on typical adsorption capacities and drug removal rates for the four devices, and indicate the relative extents to which the solid and fluid phases control the drug uptake rates.