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PubMed1965

THE PHOTO-OXIDATION OF SUCCINATE BY CHROMATOPHORES OF RHODOSPIRILLUM RUBRUM.

1. The stoicheiometry of the photo-oxidation of succinate by chromatophores has been investigated with [2,3-(14)C(2)]succinate. It was found that there is a stoicheiometric relationship between the amount of succinate oxidized and the NAD reduced, and that fumarate is the only product of succinate oxidation. 2. The possibility of a direct hydrogen transfer from succinate to NAD in this reaction was investigated with tritiated substrates. With tritiated succinate less than 3% of the activity expected if direct hydrogen transfer occurred was recovered in the NADH(2), and this was due to contamination with the substrate. In experiments with tritiated water, NADH(2) was labelled, and had half the specific activity of the water, as expected if water was the source of protons. It was also found that chromatophores catalyse an exchange reaction between NADH(2) and water. 3. It is concluded that the exchange reaction makes it impossible to interpret these results as indicating either a hydrogen-transfer or an electron-transfer mechanism for the photoreduction reaction.

Bacterial Chromatophores↗
PubMed1994

The covalent attachment of FAD to the flavoprotein of Saccharomyces cerevisiae succinate dehydrogenase is not necessary for import and assembly into mitochondria.

Succinate dehydrogenase of the bacterial or inner mitochondrial membrane catalyses the oxidation of succinate to fumarate and directs reducing equivalents into the electron-transport chain. The enzyme is also able to catalyse the reverse reaction, the reduction of fumarate to succinate. The enzyme is composed of four subunits. These subunits include a catalytic dimer composed of a flavoprotein subunit with a covalently bound FAD, and an iron-sulfur protein subunit with three different iron-sulfur centres, which is anchored to the membrane by two smaller integral membrane proteins. The FAD moiety is attached to the flavoprotein subunit by an 8 alpha-[N(3)-histidyl]FAD linkage at a conserved histidine residue, His90 of the Saccharomyces cerevisiae succinate dehydrogenase. By mutating His90 to a serine residue, we have constructed a flavoprotein subunit that is unable to covalently bind FAD. The mutant flavoprotein is targeted to mitochondria, translocated across the mitochondrial membranes, and is assembled with the other subunits where it binds FAD non-covalently. The resulting holoenzyme has no succinate-dehydrogenase activity but retains fumarate reductase activity. The covalent attachment of FAD is therefore necessary for succinate oxidation but is dispensable for both fumarate reduction and for the import and assembly of the flavoprotein subunit.

Binding Sites↗
PubMed1997

Benzoate degradation via the ortho pathway in Alcaligenes eutrophus is perturbed by succinate.

During batch growth of Alcaligenes eutrophus on benzoate-plus-succinate mixtures, substrates were simultaneously metabolized, leading to a higher specific growth rate (mu = 0.56 h-1) than when a single substrate was used (mu = 0.51 h-1 for benzoate alone and 0.44 h-1 for succinate alone), without adversely affecting the growth yield (0.57 Cmol/Cmol). Flux distribution analysis revealed that succinate dehydrogenase most probably controls the rate of total succinate consumption (the maximum flux being 9.7 mmol.g-1.h-1). It is postulated that the relative consumption rate of each substrate is in part related to modified levels of gene expression but to a large extent is dependent upon the presence of succinate, end product of the beta-ketoadipate pathway. Indeed, the in vitro beta-ketoadipate-succinyl coenzyme A transferase activity was seen to be inhibited by succinate, a coproduct of the reaction.

Adipates↗
PubMed1984

Escherichia coli succinyl coenzyme A synthetase. Inhibition of ATP-stimulated succinate----succinyl coenzyme A exchange at low succinyl coenzyme A concentrations by an ADP trap.

The hypothesis that Escherichia coli succinyl-CoA synthetase functions by a cooperative alternating sites mechanism is based largely on the results of [18O]phosphate exchange experiments (Bild, G. S., Janson, C. A., and Boyer, P. D. (1980) J. Biol. Chem. 255, 8109-8115). In those experiments, [18O]Pi----succinate (predominantly) exchange appeared to proceed at greater rates (relative to the apparent amount of succinyl-CoA released from the enzyme) at low ATP in incubations containing ATP, CoA, succinate, [18O]Pi, 0.48 M hydroxylamine (as a succinyl-CoA trap), and a pyruvate kinase-lactate dehydrogenase ADP trap. The conclusion arrived at was that succinyl-CoA binding at one site was inversely related to ATP binding at the second site. Thus, the residence time of succinyl-CoA binding at a site would be longer at lower ATP concentrations. Our experiments show that, under the incubation conditions described by Bild et al. (Bild, G. S., Janson, C. A., and Boyer, P. D. (1980) J. Biol. Chem. 255, 8109-8115), succinyl-CoA is not efficiently trapped. Thus, at ATP concentrations from 3.6 to 150 microM, concentrations of succinyl-CoA from 13 to 78 microM were observed. Succinate----succinyl-CoA exchange reactions carried out in this range of ATP and subsaturating succinyl-CoA concentrations were found to be markedly inhibited by the addition of the ADP trap. This inhibition was more pronounced at higher ATP levels. At a saturating succinyl-CoA concentration (1.5 mM), addition of the ADP trap actually stimulated succinate----succinyl-CoA exchange. Under these conditions, ATP----Pi exchange was greatly depressed. These results are interpreted as follows. ADP is required for optimal binding of succinyl-CoA, but only when the latter is present at subsaturating concentrations; thus, the ADP trap inhibits the reaction. ATP exerts its stimulatory action on succinate---- succinyl-CoA exchange through an "other site" effect, i.e. in binding to the noncatalytic site of succinyl-CoA synthetase, it facilitates binding and release of succinyl-CoA at the catalytic site. ATP may also exert negative effects by inhibiting other site binding of ATP or by interfering with same site succinyl-CoA binding at subsaturating concentrations of the latter. These data support the notion that a half-sites mechanism applies to succinyl-CoA synthetase, but suggest that the [18O]Pi----succinate exchange data which have been instrumental in development of the cooperative alternating sites hypothesis should be re-evaluated.

Acyl Coenzyme A↗
PubMed1984

Effects of dl-alpha-tocopheryl succinate in combination with sodium butyrate and cAMP stimulating agent on neuroblastoma cells in culture.

The effect of dl-alpha-tocopheryl (vitamin E) succinate in combination with Prostaglandin A2 (PGA2) and sodium butyrate on mouse neuroblastoma cells (NBP2) in culture, according to the criteria of growth inhibition and morphological differentiation (neurite formation), was studied. Results showed that PGA2 and sodium butyrate inhibited the growth of NB cells in a dose-dependent manner. The combined effects of vitamin E succinate with PGA2 or sodium butyrate, according to the criterion of growth inhibition, were additive. Vitamin E succinate by itself did not induce morphological differentiation, but it enhanced PGA2-induced morphological differentiation. Sodium butyrate alone or in combination with vitamin E succinate did not significantly increase the level of morphological differentiation. Sodium succinate and an equal amount of solvent (ethanol) failed to modify the effect of PGA2 or sodium butyrate. This suggests that the effect of vitamin E succinate in modifying the response of PGA2 and sodium butyrate on NB cells is due to the effect of vitamin E rather than to that of succinate.

Animals↗
PubMed1987

Pharmacokinetics of methylprednisolone succinate, methylprednisolone, and lidocaine in the normal dog and during hemorrhagic shock.

Pharmacokinetics of methylprednisolone succinate and methylprednisolone following methylprednisolone sodium succinate administration were studied in five dogs under normal conditions and then during a severe hemorrhagic shock. In order to evaluate hepatic blood flow, lidocaine clearance was simultaneously measured. In the normal state, the clearance of methylprednisolone succinate was 1.64 +/- 0.499 L/h/kg and its half-life was 15.33 +/- 3.84 min. The systemic availability of methylprednisolone from methylprednisolone succinate was 59.9 +/- 8.3%, and the maximal methylprednisolone concentration was observed after a delay of 7.68 +/- 6.31 min. Using a reservoir technique in anesthetized dogs, severe hemorrhagic shock was obtained. Changes in lidocaine clearance indicated a subsequent reduction of hepatic blood flow. The clearance of methylprednisolone succinate decreased to 0.488 +/- 0.240 L/kg/h, and the half-life increased to 40.66 +/- 23.48 min. The exact availability of methylprednisolone from methylprednisolone succinate during shock was not calculable because methylprednisolone kinetics were time dependent. The plasma methylprednisolone concentration was relatively high and persistent during the shock. It was concluded that methylprednisolone sodium succinate is a prodrug which can be released in sufficient quantities as its active moiety (i.e., methylprednisolone) during severe hemorrhagic shock in the dog. In addition, after a single intravenous administration, the slow process of methylprednisolone elimination may give sustained methylprednisolone concentrations for several hours.

Animals↗
PubMed2005

Effect of alpha-tocopherol and tocopherol succinate on lipid peroxidation in equine spermatozoa.

The objective of this study was to compare the effect of alpha-tocopherol and its ester, alpha tocopherol succinate, on lipid peroxidation and motility of equine spermatozoa. In experiment one, spermatozoa were incubated with dl-alpha-tocopherol (5, 25, 100 or 500 microM), DL-alpha tocopherol succinate (5, 25, 100 or 500 microM) or vehicle (0.5% ethanol) at 38 degrees C, and sperm motility was determined at 30, 60 and 120 min. In experiment two, spermatozoa loaded with the lipophilic probe, C11BODIPY(581/591), were incubated with dl-alpha-tocopherol (50 and 100 microM), DL-alpha-tocopherol succinate (50 and 100 microM) or ethanol (0.5%) and with the promoters cumene hydroperoxide, Fe2SO4, and ascorbate at 38 degrees C in 5% CO2. Lipid peroxidation was determined by changes in fluorescence of C11BODIPY(581/591), and motility was determined by CASA at 0, 15, 30 and 60 min. In experiment three, spermatozoa loaded with C11BODIPY(581/591) were incubated with dl-alpha-tocopherol (5, 25, 100 or 500 microM), DL-alpha-tocopherol succinate (5, 25, 100 or 500 microM) or ethanol (0.5%) at 38 degrees C and then submitted to a 4-hour incubation at room temperature. Motility and lipid peroxidation were determined at 1 and 4 h. In experiment four, the effect of DL alpha tocopherol (5, 25 or 500 microM), DL-alpha-tocopherol succinate (5, 25 or 500 microM) or ethanol (0.5%) on lipid peroxidation and motility were evaluated during storage at 5 degrees C in a skim-milk based extender. Although dl-alpha-tocopherol succinate appeared more effective than DL-alpha-tocopherol in preventing lipid peroxidation during short-term incubations, the succinate ester suppressed sperm motility compared to dl-alpha-tocopherol alone.

Animals↗
PubMed1981

Relative bioavailability of intravenous chloramphenicol succinate and oral chloramphenicol palmitate in infants and children.

The relative bioavailability of intravenously administered chloramphenicol succinate and orally administered chloramphenicol palmitate was compared in 18 children, age 2 months to 14 years. The area under the serum concentration vs time curve of chloramphenicol and urinary excretion of chloramphenicol succinate were determined in each child under steady-state conditions while receiving chloramphenicol succinate and again while receiving chloramphenicol palmitate. The mean AUC was significantly greater during oral therapy compared to intravenous therapy (110 vs 78 mg hr/L, P less than 0.001). The relative bioavailability of chloramphenicol succinate was 70% compared to chloramphenicol palmitate. This could be explained by the mean loss of 36% of the intravenous dose in the urine as unhydrolyzed chloramphenicol succinate. The intravenous dose of chloramphenicol succinate did not correlate with AUC (r = 0.193). However, there was a significant correlation between the oral dose of chloramphenicol palmitate and AUC (r = 0.429, P = 0.025). The bioavailability of orally administered chloramphenicol palmitate is superior to that of chloramphenicol succinate given intravenously. Furthermore, there is a greater correlation between dose and amount of active drug in the body when the oral preparation is used. Oral administration of chloramphenicol palmitate appears to offer significant therapeutic advantages in patients who can tolerate medication given orally.

Administration, Oral↗
PubMed2002

IgE-mediated anaphylactic reaction induced by succinate ester of methylprednisolone.

BACKGROUND: In systemic administration the prevalence of anaphylactic reactions attributable to corticosteroids is approximately 0.3%. Positive prick tests with different corticosteroids have been reported suggesting an immunoglobulin (Ig)E-mediated mechanism. OBJECTIVE: A 42-year-old man with multiple sclerosis developed flush, erythema, and itching a few minutes after the begin of an intravenous infusion of methylprednisolone-21-sodium succinate. DIAGNOSTIC AND RESULTS: Prick tests were found to be positive with methylprednisolone-21-sodium succinate and prednisolone-21-sodium succinate, whereas prick tests with prednisolone without ester and betamethasone-21-dihydrogen phosphate showed negative results. Oral challenge with prednisolone without ester and intravenous challenge with betamethasone-21-dihydrogen phosphate were well tolerated. Specific IgE-antibodies against methylprednisolone-21-sodium succinate were found in the serum of the patient. Because of the positive prick test and specific IgE antibodies against methylprednisolone-21-sodium succinate, the diagnosis of IgE-mediated anaphylactic reaction could be proven. Succinate ester was suspected to be immunogenic, as other corticosteroids without this particular ester or with other substitutions at the C21 remained negative both in the prick and the challenge tests. CONCLUSIONS: This patient showed an adverse reaction caused by methylprednisolone-21-sodium succinate. The uniqueness in this case was the presence of specific IgE antibodies against this esterified corticosteroid in the patient's serum proving that this reaction was based upon a true IgE-mediated mechanism.

Adult↗
PubMed2002

Open-framework cadmium succinates of different dimensionalities.

Open-framework cadmium succinates, [CN(3)H(6)](2)[Cd(2)(C(4)H(4)O(4))(Cl)(2)], I; [CN(3)H(6)](2)[Cd(C(4)H(4)O(4))(2)], II; Cd(2)(C(4)H(4)O(4))(2)(C(4)N(2)H(8))(H(2)O)(3), III; [C(4)N(2)H(12)][Cd(2)(C(4)H(4)O(4))(3)].4H(2)O, IV; Cd(C(4)H(4)O(4))(H(2)O)(2), V; and Cd(3)(C(4)H(4)O(4))(2)(OH)(2)], VI, of different dimensionalities have been synthesized by hydrothermal procedure by employing two different strategies, one involving the reaction of Cd salts with organic-amine succinates and the other involving the hydrothermal reaction of Cd salts with a mixture of succinic acid and the organic amine. While the latter procedure yields structures without any amine in them, the former gives rise to amine templated cadmium succinates with open architectures. By employing guanidinium succinate we have obtained I and II, and with piperazinium succinate we obtained III and IV. Of these I has a one-dimensional chain structure, IV has a layered structure, and II and III have three-dimensional architectures. The two cadmium succinates without incorporation of amine, V and VI, possess layered and three-dimensional structures, respectively. The three-dimensional structures II and III exhibit interpenetration similar to that in diamondoid and alpha-polonium type structures, respectively.

Journal Article↗
PubMed2001

Comparative study of a combination of isometheptene mucate, dichloralphenazone with acetaminophen and sumatriptan succinate in the treatment of migraine.

OBJECTIVE: To compare the safety and efficacy of isometheptene mucate, dichloralphenazone with acetaminophen to sumatriptan succinate for the treatment of mild-to-moderate migraine, with or without aura, when taken at the first sign of an attack. BACKGROUND: The Food and Drug Administration approved sumatriptan succinate and the combination of isometheptene mucate, dichloralphenazone with acetaminophen for the treatment of migraine. As part of the stratified treatment of migraine, those patients whose headaches are mild or moderate may benefit from nontriptan medications. Additionally, early treatment of acute migraine before the headache has become moderate or severe may improve response to treatment. METHODS: This was a multicenter, double-blind, randomized, parallel-group study to assess the safety and efficacy of the combination of isometheptene mucate, dichloralphenazone with acetaminophen and sumatriptan succinate in the early stages of a single migraine attack. Patients diagnosed with migraine, with or without aura, as defined by the International Headache Society diagnostic criteria were enrolled. RESULTS: One hundred thirty-seven patients were enrolled in the study. Data for efficacy were available for 126 patients; safety data were available for 128 patients. No statistically significant difference between the two active agents in the patient's response to treatment was demonstrated. Headache recurrence was not significantly different over the 24-hour evaluation period for those patients responding in the first 4 hours. In those with headache recurrence, it was statistically significantly more severe in those patients treated with sumatriptan succinate. Improvement in functional disability was, in general, better among those treated with isometheptene mucate, dichloralphenazone with acetaminophen. Global analysis of efficacy was similar in the two active groups. Patients treated with sumatriptan succinate were somewhat more likely to have adverse effects than the isometheptene mucate, dichloralphenazone with acetaminophen group. CONCLUSIONS: Both isometheptene mucate, dichloralphenazone with acetaminophen and sumatriptan succinate are safe and effective when used early in the treatment of an acute migraine. Several parameters suggest that isometheptene mucate, dichloralphenazone with acetaminophen may have a slight advantage compared with sumatriptan succinate in the early treatment of mild-to-moderate migraine.

Acetaminophen↗
PubMed1999

All-rac-alpha-tocopherol acetate is a better vitamin E source than all-rac-alpha-tocopherol succinate for broilers.

The difference in bioavailabilities of the acetate and succinate esters of all-rac-alpha-tocopherol was investigated in a feeding experiment with broilers. The experiment was initiated with 96 12-d-old male Cobb broilers and lasted for 4 wk. The two sources of vitamin E were fed to eight groups of broilers at four different dietary levels (50, 100, 150 and 200 mg/kg feed, including the naturally occurring alpha-tocopherol). A total collection of droppings for determination of apparent tocopherol absorption were performed at two separate time periods (d 28-34 and d 35-41). There were no differences among the eight experimental groups with respect to animal performance or feed intake. At all dietary levels, the apparent absorption coefficient for all-rac-alpha-tocopherol succinate was significantly lower than that of the acetate ester. The mean (+/- SD) apparent absorption coefficient for all-rac-alpha-tocopherol succinate was 58.0 +/- 5.4 compared with 70. 8 +/- 5.6 for all-rac-alpha-tocopherol acetate. Furthermore, the apparent absorption coefficients for both esters was significantly lower in the first collection period (d 28-34) than in the second collection period (d 35-41). This difference in the apparent absorption coefficient between the succinate and the acetate ester was accompanied by significant differences in alpha-tocopherol concentrations in plasma, breast muscle, liver and adipose tissue of the broilers, which were lower in those fed the succinate ester. Based on a comparison of plasma and tissue responses, the succinate ester was utilized only 69-76% as efficiently as the acetate ester. In vitro studies showed a significantly higher capacity of pancreatic carboxyl ester hydrolase to hydrolyze alpha-tocopherol acetate compared to alpha-tocopherol succinate. This difference in intestinal hydrolysis of the two vitamin E sources may explain the observed differences in biopotency.

Animal Feed↗
PubMed1971

The Respiratory Chain of Plant Mitochondria: XI. Electron Transport from Succinate to Endogenous Pyridine Nucleotide in Mung Bean Mitochondria.

Energy-linked reverse electron transport from succinate to endogenous NAD in tightly coupled mung bean (Phaseolus aureus) mitochondria may be driven by ATP if the two terminal oxidases of these mitochondria are inhibited, or may be driven by the free energy of succinate oxidation. This reaction is specific to the first site of energy conservation of the respiratory chain; it does not occur in the presence of uncoupler. If mung bean mitochondria become anaerobic during oxidation of succinate, their endogenous NAD becomes reduced in the presence of uncoupler, provided that both inorganic phosphate (P(i)) and ATP are present. No reduction occurs in the absence of P(i), even in the presence of ATP added to provide a high phosphate potential. If fluorooxaloacetate is present in the uncoupled, aerobic steady state, no reduction of endogenous NAD occurs on anaerobiosis; this compound is an inhibitor of malate dehydrogenase. This result implies that endogenous NAD is reduced by malate formed from the fumarate generated during succinate oxidation. The source of free energy is most probably the endogenous energy stores in the form of acetyl CoA, or intermediates convertible to acetyl CoA, which removes the oxaloacetate formed from malate, thus driving the reaction towards reduction of NAD.In the absence of P(i) and presence of oligomycin, oxidation of succinate by the alternative cyanide-insensitive oxidase pathway, in the presence of sulfide to inhibit cytochrome oxidase, does not reduce endogenous NAD, either in the aerobic steady state or in anaerobiosis. Under these conditions, only the reversed electron transport pathway from succinate to endogenous NAD is active and ATP cannot interact with the respiratory chain. The source of energy for NAD reduction must come from the respiratory chain, and this result shows that oxidation of succinate through the alternate pathway does not provide this energy.

Journal Article↗
PubMed1988

Production of succinic Acid from citric Acid and related acids by lactobacillus strains.

A number of Lactobacillus strains produced succinic acid in de Man-Rogosa-Sharpe broth to various extents. Among 86 fresh isolates from fermented cane molasses in Thailand, 30 strains (35%) produced succinic acid; namely, 23 of 39 Lactobacillus reuteri strains, 6 of 18 L. cellobiosus strains, and 1 of 6 unidentified strains. All of 10 L. casei subsp. casei strains, 5 L. casei subsp. rhamnosus strains, 6 L. mali strains, and 2 L. buchneri strains did not produce succinic acid. Among 58 known strains including 48 type strains of different Lactobacillus species, the strains of L. acidophilus, L. crispatus, L. jensenii, and L. parvus produced succinic acid to the same extent as the most active fresh isolates, and those of L. alimentarius, L. collinoides, L. farciminis, L. fructivorans (1 of 2 strains tested), L. malefermentans, and L. reuteri were also positive, to lesser extents. Diammonium citrate in de Man-Rogosa-Sharpe broth was determined as a precursor of the succinic acid produced. Production rates were about 70% on a molar basis with two fresh strains tested. Succinic acid was also produced from fumaric and malic acids but not from dl-isocitric, alpha-ketoglutaric, and pyruvic acids. The present study is considered to provide the first evidence on the production of succinic acid, an important flavoring substance in dairy products and fermented beverages, from citrate by lactobacilli.

Journal Article↗
PubMed1991

Influence of CO(2)-HCO(3) Levels and pH on Growth, Succinate Production, and Enzyme Activities of Anaerobiospirillum succiniciproducens.

Growth and succinate versus lactate production from glucose by Anaerobiospirillum succiniciproducens was regulated by the level of available carbon dioxide and culture pH. At pH 7.2, the generation time was almost doubled and extensive amounts of lactate were formed in comparison with growth at pH 6.2. The succinate yield and the yield of ATP per mole of glucose were significantly enhanced under excess-CO(2)-HCO(3) growth conditions and suggest that there exists a threshold level of CO(2) for enhanced succinate production in A. succiniciproducens. Glucose was metabolized via the Embden-Meyerhof-Parnas route, and phosphoenolpyruvate carboxykinase levels increased while lactate dehydrogenase and alcohol dehydrogenase levels decreased under excess-CO(2)-HCO(3) growth conditions. Kinetic analysis of succinate and lactate formation in continuous culture indicated that the growth rate-linked production rate coefficient (K) cells was much higher for succinate (7.2 versus 1.0 g/g of cells per h) while the non-growth-rate-related formation rate coefficient (K') was higher for lactate (1.1 versus 0.3 g/g of cells per h). The data indicate that A. succiniciproducens, unlike other succinate-producing anaerobes which also form propionate, can grow rapidly and form high final yields of succinate at pH 6.2 and with excess CO(2)-HCO(3) as a consequence of regulating electron sink metabolism.

Journal Article↗
PubMed1970

Catabolic Activities of Neisseria meningitidis: Utilization of Succinate.

When resting cells of Neisseria meningitidis group B were incubated with either succinate, fumarate, or malate, respiration and CO(2) production were not significantly stimulated. These dicarboxylic acids were readily utilized, however, when they were added in association with a combination of alpha-ketoglutarate and aspartate or with glucose or with glutamate. The amounts of these substrates required for exogenous succinate utilization were relatively large. Both the alpha-ketoglutarate-aspartate combination and glutamate greatly stimulated succinate uptake into the cells, but glutamate was far more effective than the alpha-ketoglutarate-aspartate combination in eliciting exogenous succinate utilization. This difference is explained on the basis of evidence reported in another article that succinate derived from the alpha-ketoglutarate-aspartate mixture is metabolized more rapidly-and thus more rapidly dilutes the specific activity of added succinate-than the succinate derived from glutamate.

Journal Article↗
PubMed2003

Extended-release metoprolol succinate in chronic heart failure.

OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, and tolerability of extended-release (ER) metoprolol succinate and its role in the management of chronic heart failure. DATA SOURCES: A MEDLINE search of English-language literature (1990-October 2002) was conducted using congestive heart failure and metoprolol CR/XL or metoprolol CR/ZOK as search terms to identify pertinent studies. STUDY SELECTION/DATA EXTRACTION: All of the articles identified from the data sources were evaluated, with priority given to randomized, double-blind, placebo-controlled studies. DATA SYNTHESIS: ER metoprolol succinate is a controlled-release tablet designed to produce even and consistent beta(1)-blockade throughout the 24-hour dosing interval, with less fluctuation in metoprolol plasma concentrations compared with immediate-release metoprolol. Three randomized, double-blind, placebo-controlled trials have evaluated the efficacy of ER metoprolol succinate in the treatment of patients with chronic heart failure. The MERIT-HF (Metoprolol CR/XL Randomized Intervention Trial in Congestive Heart Failure) study, the largest of these trials and the largest randomized mortality trial with beta-blockers in heart failure to date, demonstrated that ER metoprolol succinate reduced the relative risk of all-cause mortality by 34% versus placebo. Furthermore, the relative risk of the combined endpoint of mortality plus all-cause hospitalizations was reduced by 19% and sudden death was reduced by 41%. The benefits of therapy were evident in various patient subgroups, including elderly patients and those with diabetes mellitus. ER metoprolol succinate was generally well tolerated, with a similar proportion of patients discontinuing therapy due to adverse events relative to placebo (9.8% and 11.7%, respectively). CONCLUSIONS: ER metoprolol succinate therapy provides substantial mortality and morbidity benefits in patients with New York Heart Association class II and III heart failure who are stabilized on angiotensin-converting enzyme inhibitors and diuretics. ER metoprolol succinate is administered once daily, is well tolerated, and provides consistent beta(1)-blockade over the 24-hour dosing interval.

Delayed-Action Preparations↗
PubMed2005

Compatibility of ondansetron hydrochloride and methylprednisolone sodium succinate in multilayer polyolefin containers.

PURPOSE: The compatibility of ondansetron hydrochloride and methylprednisolone sodium succinate in 5% dextrose injection and 0.9% sodium chloride injection was studied. METHODS: Test solutions of ondansetron hydrochloride 0.16 mg/mL and methylprednisolone sodium succinate 2.4 mg/mL were prepared in triplicate and tested in duplicate. Total volumes of 4 and 2 mL of ondansetron hydrochloride solution and methylprednisolone sodium succinate solution, respectively, were added to 50-mL multilayer polyolefin bags containing 5% dextrose injection or 0.9% sodium chloride injection. Bags were stored for 24 hours at 20-25 degrees C and for 48 hours at 4-8 degrees C. Chemical compatibility was measured with high-performance liquid chromatography, and physical compatibility was determined visually. RESULTS: Ondansetron hydrochloride was stable for up to 24 hours at 20-25 degrees C and up to 48 hours at 4-8 degrees C. Methylprednisolone sodium succinate was stable for up to 48 hours at 4-8 degrees C. When stored at 20-25 degrees C, methylprednisolone sodium succinate was stable for up to 7 hours in 5% dextrose injection and up to 24 hours in 0.9% sodium chloride injection. Compatibility data for solutions containing ondansetron hydrochloride plus methylprednisolone sodium succinate revealed that each drug was stable for up to 24 hours at 20-25 degrees C and up to 48 hours at 4-8 degrees C. CONCLUSION: Ondansetron 0.16 mg/mL (as the hydrochloride) and methylprednisolone 2.4 mg/mL (as the sodium succinate) mixed in 50-mL multilayer polyolefin bags were stable in both 5% dextrose injection and 0.9% sodium chloride injection for up to 24 hours at 20-25 degrees C and up to 48 hours at 4-8 degrees C.

Antiemetics↗