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PubMed1993

Thermodynamics of the maleate and citraconate hydration reactions catalysed by malease from Pseudomonas pseudoalcaligenes.

Malease from Pseudomonas pseudoalcaligenes catalyses the hydration of both maleate and citraconate to D-malate and D-citramalate, respectively. The Kapp for these hydration reactions were 2050 and 104, respectively, under standard biochemical conditions (25 degrees C, pH 7.0, I = 0.1). The influence of the pH (6.0-8.5) on Kapp was determined. The Gibbs-free-energy changes under standard biochemical conditions for the hydration of the dianionic acids were calculated to be -19.28 kJ.mol-1 and -11.65 kJ.mol-1, respectively. From the obtained data together with data from the literature, the Gibbs free energy of formation of maleate2- and citraconate2- were calculated to be -588.91 kJ.mol-1 and -600.56 kJ.mol-1, respectively. The influence of the temperature (10-40 degrees C) on Kapp was determined for both hydration reactions. The enthalpy change (delta H degrees') and entropy change (delta S degrees') under standard biochemical conditions for the maleate2- (delta H degrees' = 18.07 kJ.mol-1, delta S degrees' = 2.94 J.mol-1 x K-1) and citraconate2- (delta H degrees' = -22.55 kJ.mol-1, delta S degrees' = -35.92 kJ.mol-1 x K-1) hydration reactions were calculated. The reaction rate of malease from Ps. pseudoalcaligenes was studied for both hydration reactions as a function of temperature. From these studies, the Gibbs free energies of activation for the maleate and citraconate hydration reactions catalysed by malease from Ps. pseudoalcaligenes were calculated to be 62.21 kJ.mol-1 and 63.43 kJ.mol-1, respectively.

Catalysis↗
PubMed1993

Microbial production of D-malate from maleate.

To produce D-malate from maleate by a microbial reaction, we screened a number of maleate-utilizing microorganisms for enzyme activity by an intact cell system. The strain which showed the best productivity among the 440 strains tested was identified taxonomically as Arthrobacter sp. strain MCI2612. The optical purity of the malate produced by this strain was 100% D type. The culture and reaction conditions for the production were studied for this strain. Addition of amino acids such as L-proline, L-histidine, and L-arginine to the culture medium promoted the formation of reaction activity as well as cell growth. Under optimum conditions, 87 g of D-malate per liter was produced in 20 h. The yield was 72 mol%.

Arthrobacter↗
PubMed1985

Renal albumin reabsorption in normal and sodium maleate-treated rats.

The normal filtered load of albumin at the rat glomerulus was estimated to be 18 mg/24 h X g kidney weight by means of micropuncture studies. Total nephron fractional reabsorption was 91%. The proximal convoluted tubule accounted for 72% of total reabsorption followed by an additional 12% in the loop of Henle. Only minimal protein uptake occurred in more distal parts of the nephron. Na maleate, given at a dosage of 2 mM/kg body weight 2 h prior to micropuncture, inhibited tubular albumin uptake in the proximal convoluted tubule. As in controls there was no measurable protein uptake beyond the loop of Henle. These results indicated that tubular reabsorption of albumin was virtually completed by the early distal convoluted tubule. Maleate was found to be a potent inhibitor of protein transport in the proximal convoluted tubule resulting in a fractional excretion of albumin of 50%.

Animals↗
PubMed1999

Time dependent pharmacokinetic interaction between phenylpropanolamine and chlorpheniramine maleate in human subjects.

The influence of time of administration on the serum levels of phenylpropanolamine when administered alone and in combination with chlorpheniramine maleate at two different times of a day was studied in healthy human volunteers in a randomized 4 x 4 Latin square crossover design with a washout period of ten days. Blood samples were collected at predetermined time intervals and serum samples were analysed for unchanged phenylpropanolamine using high performance liquid chromatography. The various pharmacokinetic parameters of phenylpropanolamine were calculated using model independent methods. There was a significant (P < 0.05) decrease in the rate of absorption of phenylpropanolamine following its administration in combination with chlorpheniramine maleate at 2200 hours. However, such a change was not observed for treatment at 1000 hours. The observed change may be due to the time dependent gastrointestinal effect of these drugs.

Chlorpheniramine↗
PubMed1984

[Effect of a betamethasone-dimethidine-maleate combination on dermatologic diseases. Determination of plasma cortisol levels before, during and after several days' therapy].

The combination of betamethasone and dimetindene maleate (Fenistil Plus) is a new combination of a corticosteroid and an antihistaminic agent. According to the pharmaceutical formula, patients must take three capsules daily, whereby only the morning dose contains betamethasone as well as the antihistaminic. The aim of the study, which was performed on dermatological cases, was to examine the restitution of plasma cortisol concentrations following circadian betamethasone therapy of several days duration, as well as to confirm the clinical effectiveness of the drug combination. The results obtained in the study, carried out in a total of nine Patients suffering from various types of dermatitis, showed that the desired therapeutic effects were achieved. In three patients, plasma cortisol concentrations were found to have returned to normal values within four days after cessation of a ten days treatment. From the above results it may be concluded that permanent adrenocortical suppression is not to be expected in patients treated with betamethasone (0,75 mg) in the morning, for a period of ten days. Furthermore, it may be stated that dimetindene maleate (3 mg/day) in combination with the morning dose of betamethasone proved to be therapeutically effective.

Administration, Oral↗
PubMed1984

Enhancement of the DNA cross-linking activity of nitrogen mustard by misonidazole and diethyl maleate in a mouse fibrosarcoma tumor in vivo.

We have used the technique of alkaline elution to determine the amount of nitrogen mustard (HN2)-induced DNA cross-linking in a murine fibrosarcoma tumor in vivo. Mice were either treated with HN2 directly or were pretreated with misonidazole (MISO) or diethyl maleate prior to injection with HN2. Two types of HN2-induced DNA lesions were detected, namely, proteinase K-sensitive and -resistant cross-links. Pretreatment with MISO did not appear to affect the ratio of the two types of lesion. In mice treated with HN2 alone, the amount of cross-linking reached a high level by 0.5 hr postinjection, after which these lesions were repaired, 62% of cross-links being removed between 0.5 hr and 6 hr postinjection. Pretreatment of mice with MISO resulted in substantial alterations in both the magnitude and time course of cross-linking during the first few hr after injection of HN2. Both MISO and diethyl maleate enhanced the number of cross-links formed at 0.5 hr postinjection. Furthermore, in MISO-pretreated mice, only 18% of the cross-links present at 0.5 hr had been removed by 6 hr postinjection. This early enhancement is possibly related to glutathione depletion resulting in reduced intracellular inactivation of HN2. Since repair processes were determined not to be saturated at the level of lesions under study, these data suggest that, in addition to the initial glutathione depletion resulting in an increased burden of damage, MISO may also inhibit DNA repair processes, possibly via a hypoxia-dependent interaction between MISO reduction products and DNA or repair enzymes. Assuming that DNA cross-linking is related to the cytotoxicity of HN2, these effects may account for the MISO enhancement of HN2 toxicity toward various biological systems which have been reported previously. It appears that chemosensitization may result from a variety of factors, with the relative importance of each factor depending on the particular drug being used.

Animals↗
PubMed1984

Effect of topical timolol maleate on exercise performance.

The effect of topical timolol maleate on exercise performance was investigated in a randomized double-blind study. Healthy young subjects underwent two graded maximal exercise evaluations on a treadmill. The evaluations were given one week apart. Before each trial, the subjects were given a single drop of either placebo or 0.5% timolol maleate in each eye. The results indicate that topical timolol has a statistically significant effect on both maximal heart rate and time to exhaustion. However, we found that the drug had no effect on the physiologic parameters of Vo2, respiratory rate, Vco2, or respiratory quotient.

Administration, Topical↗
PubMed2001

Determination of trimebutine maleate in rat plasma and tissues by using capillary zone electrophoresis.

A simple and rapid capillary zone electrophoresis method was developed for the determination of trimebutine maleate in rat plasma and tissues. Rat plasma and tissue homogenates were mixed with acetonitrile containing internal standard, ephedrine hydrochloride, and then centrifuged. The supernatant was dried under a stream of nitrogen, and the residue was reconstituted in methanol-water (1:1). The electrophoresis was performed in uncoated capillary with 30 mmol/L phosphate buffer of pH 6.0 as the separation electrolyte. The applied voltage was 10 kV and the UV detection was set at 214 nm. The peak height ratio vs concentration in plasma or homogenates was linear over the range of 5-500 ng/mL and the limit of quantitation was 5 ng/mL. The intra- and inter-day precision was RSD < 14% and <15%. The accuracy was relative error (RE) within +/- 14%. This method was applied to studying the pharmacokinetics and tissue distribution after a single dose of trimebutine maleate was administrated to the rats. The T(max), AUC, C(max) and t(1/2) were 30 min, 7.8 x 10(2) (ng/mL) min, 39 ng/mL and 1.7 x 10(2) min. The drug distribution was found in a decreasing order of liver, kidney, spleen, lung and heart.

Animals↗
PubMed1990

Ergonovine maleate test detects anginal patients with poorly reproducible exercise tests.

The aim of the study is to evaluate the reproducibility of exercise testing and to determine whether there is any correlation between the reproducibility of exercise test and response to the ergonovine maleate test. Thirty-eight patients with mixed angina and documented coronary artery disease underwent an ergonovine maleate test and four exercise tests on consecutive days in the same basal conditions. The ergonovine test was positive in 20 patients (Group I) and negative in 18 patients (Group II). There were no significant differences in the clinical and angiographic data of the two groups. All 152 exercise tests were positive. The variability of the response of the repeated tests was assessed by means of an analysis of the following parameters: heart rate, blood pressure, rate-pressure product, watts, and minutes were recorded at the onset of ischemia (ST decreases greater than or equal to 0.1 mV). Range (maximal-minimal obtained value), ratio between range and maximal obtained value, and coefficient of variation (standard deviation/mean of the four parameters) were calculated for each patient. The analysis of these values demonstrated that while the test was reproducible in some patients, a high individual variability was present in others. Moreover, the individual variability results were higher in Group I than in Group II, with a statistically significant difference for all considered parameters. In conclusion, it is possible to have a poorly reproducible exercise test in patients with mixed angina. The correlation between a positive ergonovine test and a poorly reproducible exercise test suggests that abnormal coronary vasomotion may sometimes be present during exercise and may affect the reproducibility of the test.

Adult↗
PubMed1978

The role of methylergonovine maleate in augmenting extraamniotic saline for midtrimester abortion.

This study was conducted in Bombay, India, to evaluate the role of oral methylergonovine maleate (Methergine, Sandoz Pharmaceuticals, East Hanover, N.J., USA) in augmenting the effect of intermittent extraamniotic instillation of 20% saline for midtrimester abortion in 200 patients. Methylergonovine maleate (MEM) administration was randomly allocated to half the study subjects. All the study procedures were performed by a single operator, and to minimize evaluator bias, another physician evaluated all the study patients after abortion. This study showed that a statistically significant higher percentage of patients in the MEM treated group aborted within 24 hours. At 36 and 48 hours, the differences were not statistically significant, although the cumulative abortion rates were higher for subjects who received the drug than for those who did not. The incidence of incomplete abortions was lower for those treated with MEM than for those not treated with the drug, but the difference was not statistically significant. The rates of complications and side effects were similar for both study groups.

Abortion, Induced↗
PubMed1980

IR and X-ray diffraction study of chlorpheniramine maleate-montmorillonite interaction.

As a contribution to studies on the adsorption of drugs by clay minerals aimed at achieving sustained action in the oral administration of antihistamines, the adsorption of chlorpheniramine maleate by sodium montmorillonite was studied by X-ray diffraction and IR spectroscopy. The results indicated that the chlorphenirammonium ion penetrated into the interlayer space of montmorillonite, producing an increase in the basal spacing, d001, of the silicate. This increase was influenced, as was the amount adsorbed, by the pH and the concentration of the chlorpheniramine maleate solution. At pH 7.0, the amount adsorbed was close to the exchange capacity, and the complex formed had a basal spacing of 17.14 A (delta = 7.54 A). The only mechanism responsible for the interaction was cation exchange. The complex at 17.14 A must be a monolayer with the benzene rings positioned perpendicular to the surface of the oxygen atoms.

Bentonite↗
PubMed1981

High-performance liquid chromatographic assay of perhexiline maleate in plasma.

A sensitive assay is described for the calcium antagonist perhexiline maleate. Alkalinized plasma was extracted with nb-hexane, the organic phase was evaporated, and the residue was dansylated prior to analysis by reversed-phase high-performance liquid chromatography using a fluorescence detector. Perhexiline was resolved from its mono- and dihydroxylated metabolites, and the limit of sensitivity was 5 ng of perhexiline/ml. This limit represents approximately 100 times the sensitivity of the previously described GLC assay. Single-dose pharmacokinetic studies were performed with 150- and 300-mg oral doses of perhexiline maleate in five patients with severe angina pectoris and impaired left ventricular function. Peak plasma perhexiline levels occurred 3-6 hr after drug ingestion in four patients and after 12-18 hr in the fifth patient. The mean elimination half-life, measured 24 hr after drug ingestion, varied with plasma perhexiline concentration. It was 11.2 +/- 2.1 hr after the 150-mg dose and 19.1 +/- 2.8 hr after the 300-mg dose. The mean ratio of areas under the concentration-time curve for the 300-versus 150-mg doses ws 5.3:1, suggesting that hepatic metabolism of perhexiline may be saturable and that the bioavailability of perhexiline is dose dependent.

Aged↗
PubMed1981

GLC analysis of menthol, phenol, benzocaine, and pyrilamine maleate in aerosol spray lotion.

A GLC method is presented for the quantitative determination of menthol, phenol, benzocaine, and pyrilamine maleate. The propellent was exhausted from a pressurized can, and an aliquot of the alcoholic base was weighed. After the addition of the internal standard diluted with chloroform, 1 microliter of the mixture was injected in the chromatograph with a flame-ionization detector and a glass column packed with 2.5% OV-225. Average recoveries were 100.3 +/- 1.4, 100.0 +/- 1.4, 101.3 +/- 1.5, and 101.5 +/- 1.5% for menthol, phenol, benzocaine, and pyrilamine maleate, respectively.

Aerosols↗
PubMed1991

Development of a new controlled-release formulation of chlorpheniramine maleate using in vitro/in vivo correlations.

Development of a controlled-released formulation of chlorpheniramine maleate is described, using in vitro/in vivo correlates, according to a process that has been termed "biorelevant dissolution". The process begins with simulations using several possible input rates combined with known disposition parameters of chlorpheniramine maleate. Based on desired plasma concentrations, an input rate is selected for further development which consists of a combination of clinical bioequivalence studies and further in vitro testing and simulations. The method is designed to reduce the requirements for trial and error clinical bioequivalence testing of a new controlled-release formulation.

Administration, Oral↗
PubMed1990

Time course of the effect of intravenous dimetindene maleate.

In order to evaluate the time course of its effects, dimetindene maleate has been investigated in a histamine provocation model in man. Eight healthy male volunteers were treated i.v. with 4 mg dimetindene maleate or sodium chloride solution in a double blind, cross over study. Intracutaneous histamine injections were given at -1, 2, 5, 14, 17, 20, 23, 26, and 29 h following drug administration and the areas of flares and wheals were measured after 5, 10, 20, and 30 min. There was strong inhibition of the development both of flares and wheals, which was more pronounced for the former. Baseline adjusted areas under the curve differed significantly following drug and placebo treatment. The maximum effect was observed at 2 h. The mean residence time of the inhibitory effect was calculated to be approximately 13 h compared to the mean residence time of dimetindene in blood of approximately 5 h, which indicates a non-linear relationship between blood level and effect.

Adult↗
PubMed1984

Discriminative stimulus properties of pizotifen maleate (BC105): a putative serotonin antagonist.

Rats were trained to discriminate the putative serotonin (5-HT) antagonist, pizotifen maleate (BC105), from saline using a two-lever drug discrimination paradigm. Pizotifen maleate (6 mg/kg, 14.6 mumol/kg, IP) or saline was administered 55 min prior to the operant training session. The pizotifen discriminative stimulus (DS) had a rapid onset (less than 7 min) and was of long duration. The pizotifen DS was dose dependent. The pizotifen DS did not generalize to the putative 5-HT antagonists, methiothepin, xylamidine, and cinanserin. Partial generalization was observed to methysergide and metergoline, and complete generalization to cyrproheptadine and the phenothiazine antihistamine, promethazine. The pizotifen DS failed to generalize to the antipsychotic chlorpromazine, the ethanolamine antihistamine diphenhydramine, the CNS stimulant, d-amphetamine, and the putative 5-HT agonists, LSD and quipazine. LSD and quipazine failed to antagonize the pizotifen DS. The results of this study suggest that different DS properties are associated with the different putative 5-HT antagonists and that pizotifen and cyproheptadine, in addition to their reported 5-HT antagonist properties, share a common property that is also associated with promethazine, probably involving antihistaminergic activity.

Animals↗
PubMed1981

Lipid and lysosomal enzymes in human fibroblasts cultured with perhexiline maleate.

To understand the mechanism of the lysosomal lipid storage induced by perhexiline maleate, we performed simultaneous lipid analysis and lysosomal enzymes determinations. Human fibroblasts were cultured for 5 days in the presence of perhexiline maleate at a concentration of 2 micrograms/ml of culture medium. Lipid analysis showed that those non toxic levels determined the same changes as seen with higher concentrations of the drug (Hauw et al. 1980) i. e. increase of cholesterol and of all major phospholipids. Qualitative phospholipid pattern was not markedly changed. Lysosomal enzymes activities were not modified with the exception of sphingomyelinase which was reduced to 12% of its normal level.

Cells, Cultured↗
PubMed1990

Effect-time-relation of the H1-receptor antagonist dimethindene maleate following intravenous injection.

We have investigated the time-course of the weal and flare inhibiting activity of dimethindene maleate in man and compared the resulting effect-kinetic data with those from pharmacokinetic investigations. The study was carried out in a double blind, placebo controlled cross-over design with randomly assigned healthy volunteers. Dimethindene maleate (4 mg) was intravenously injected, followed by intracutaneous histamine provocations (-1, 2, 5, 14, 17, 20, 23, 26, and 29 h). The two cross-over periods were separated by a wash-out phase of 17 h. Flare and weal areas were documented 5, 10, 20, and 30 min after provocation with histamine. A strong inhibition of the development of flares and weals was observed and was more pronounced in flares than in weals. With regard to the time course of the inhibiting effect, its maxima both for flares and weals were observed at a provocation time of 2 h. The mean residence time of the inhibiting effect was calculated to be ca. 13 h for flares and ca. 15 h for weals. These values are nearly 2-3 times as high as the mean residence time of 6 h calculated from blood level data. Blood- and effect-levels are thus non-linearly related.

Adult↗