Citrate Salts Research Articles

Transport of Fentanyl Through Pig Buccal and Esophageal Epithelia in Vitro. Influence of Concentration and Vehicle pH

To validate pig esophageal epithelium as a model for the permeability barrier of the buccal mucosa, the transport of fentanyl across the two tissues was compared in vivo. The epithelia were separated by immersing the excised mucosae into an isotonic saline solution at 60--65 degrees C. Fentanyl was delivered as the citrate salt at a concentration of 1 or 2 mg/mL buffered at one of four pH values (between 6.0 and 7.4). Across both barriers, drug transport increased proportionally with concentration as expected. However, drug flux was not linearly related to the unionized fraction of the drug; indeed, fentanyl delivery was significant even when 98.5% of the drug was in the ionized form. Buccal and esophageal fluxes were very similar under all conditions suggesting that the esophageal epithelium is a representative tool for buccal transport studies in vitro.

Dietary Potassium Citrate Does Not Harm the pcy Mouse: A Brief Communication

Formation of multiple cysts in the kidneys occurs in several inherited diseases and often leads to terminal kidney failure. Because there is no definitive therapy to halt or slow the progression of renal cystic disease in people, numerous studies have examined possible therapies in animal models. Autosomal-dominant polycystic kidney disease (ADPKD) in the Han:SPRD rat is ameliorated when alkalinizing citrate salts are provided in drinking solutions. By contrast, pcy mice with cystic disease fare worse with the same treatment. We tested the hypothesis that pcy mice ingesting citrate salts in the feed would not be adversely affected by this treatment. Male homozygous pcy mice were given regular feed or 6% potassium citrate-supplemented feed and ad libitum access to water starting at 3 weeks of age. The survival curves of the treated and untreated mice were not significantly different. We conclude that treatment with potassium citrate in the feed does not affect the progression of renal cystic disease in the pcy mouse. This model closely resembles human adolescent nephronophthisis (NPHP3). Based on these findings, citrate treatment cannot be recommended for NPHP3. The fact that it did no harm, however, removes a significant barrier to its consideration as a therapy for ADPKD.

Calcium fortification of food can add unneeded dietary phosphorus

This study reports the amount of unneeded phosphorus that can be added to a diet when calcium phosphate compounds are used for calcium fortification of foods. Calcium fortified orange juice concentrate, vegetable juice, butter substitute, and dry mix for beverage were obtained from grocery stores, prepared according to instructions, and analyzed for calcium and phosphate. Single servings of these food items fortified with calcium phosphate compounds could add 400 mg of phosphorus to a diet that already provides as much as twice the recommended intake for phosphorus. Calcium compounds free of phosphate such as the gluconate, lactate, sulfate, citrate, acetate, and carbonate salts should be used to fortify foods to increase calcium intake relative to an adequate phosphorus intake to promote optimal bone health.

Poly(amidoamine) salt form: effect on pH-dependent membrane activity and polymer conformation in solution.

On exposure to an acidic pH, linear poly(amidoamine)s (PAAs) cause membrane perturbation and consequently have potential as endosomolytic polymers for the intracellular delivery of genes and toxins. Previous studies used PAAs in the hydrochloride form only. The aim of this study was to investigate systematically the effect of the PAA counterion on pH-dependent membrane activity, general cytotoxicity, and PAA solution properties to help guide optimization of PAA structure for further development of PAA-protein conjugates. PAAs (ISA 1, 4, 22, and 23; M(w) 10000-50000 g/mol) were synthesized to provide a library of PAAs having different counterions including the acetate, citrate, hydrochloride, lactate, phosphate, and sulfate salts. pH-Dependent membrane activity was assessed using a rat red blood cell haemolysis assay (conducted at a starting pH of 7.4, 6.5, or 5.5; 1 mg/mL; 1 h), and general cytotoxicity was investigated using a murine melanoma cell line (B16F10) and a human bladder endothelial-like cell line (ECV-304). Whereas poly(ethyleneimine) was haemolytic at the starting pH of 7.4 at 1 h [ approximately 50% haemoglobin (Hb) release], none of the PAA salts were haemolytic at a starting pH of 7.4 or 6.5. Although PAA acetate, citrate, and lactate were also non-haemolytic at the starting pH of 5.5, the sulfate and hydrochloride forms caused significant haemolysis (up to 80% Hb release) and ISA 22 and 23 phosphate were also markedly haemolytic ( approximately 70% Hb release). These counterion-specific differences were also clearly visible using scanning electron microscopy, which was used to visualize the red blood cell morphology. All PAAs were relatively nontoxic (IC(50) >or= 300-5000 microg/mL) compared to poly-l-lysine (IC(50) = 2-10 microg/mL), the PAA hydrochloride salts produced the greatest cytotoxicity, and the B16F10 cells were more sensitive than the ECV-304 cells. Small-angle neutron scattering suggested that ISA 23 hydrochloride had a larger hydrodynamic radius (5.1 +/- 0.2 nm) than the citrate salt (3.1 +/- 0.2 nm). These results provide indirect evidence for the salt- and pH-dependent changes in the conformation of the polymer coil. This study clearly demonstrates the importance of optimization of the counterion form when developing endosomolytic polymers designed to mediate pH-dependent membrane permeabilization.

Characterization of Bi 4Ti 3O 12 powder prepared by the citrate and oxalate coprecipitation processes

Bismuth titanate (Bi 4Ti 3O 12) powder was prepared by citrate and oxalate coprecipitation of bismuth nitrate pentahydrate, Bi(NO 3) 3·5H 2O and titanium butoxide, Ti(OC 4H 9) 4. The intermediate products with 500–1000 °C calcination were characterized using the XRD. At low temperature, Bi 4Ti 3O 12 powder and some impurities were detected. At 1000 °C, the purified powder was obtained. At 700 °C and above, the powder underwent a phase transformation from tetragonal to orthorhombic. By using the TGA, the intermediates prepared by the citrate and oxalate coprecipitation processes were the citrate salt and the oxalate–hydroxide mixture, respectively. The FTIR analysis showed the TiO stretching in the 811–816 and 574–584 cm −1. The morphologies shown by the SEM micrographs were consistent with the XRD patterns.

Alkaline chitosan solutions

Rigid and transparent hydrogels were obtained upon pouring chitosan salt solutions into saturated ammonium hydrogen carbonate. Incubation at 20 °C for 5 days yielded chitosan carbamate ammonium salt, Chit-NHCO 2 −NH 4 + a chemical species that either by hydrolysis or by thermal treatment decomposed to restore chitosan in free amine form. Chitosans of different degrees of acetylation, molecular sizes and origins (squid and crustaceans) were used as hydrochloride, acetate, glycolate, citrate and lactate salts. Their hydrogels obtained in ammonium hydrogen carbonate yielded chitosan solutions at pH values as high as 9.6, from which microspheres of regenerated chitosans were obtained upon spray-drying. These materials had a modest degree of crystallinity depending on the partial acylation that took place at the sprayer temperature (168 °C). Citrate could cross-link chitosan and impart insolubility to the microspheres. Chloride on the contrary permitted to prepare microspheres of chitosan in free amine form. By the NH 4HCO 3 treatment, the cationicity of chitosan could be reversibly masked in view of mixing chitosan with alginate in equimolar ratio without coacervation. The clear and poorly viscous solutions of mixed chitosan carbamate and alginate were spray-dried at 115 °C to manufacture chitosan–alginate microspheres having prevailing diameter approx 2 micron.

Setting behavior of ultra-low cement refractory castables in the presence of citrate and polymethacrylate salts

The effect of citrate and polymethacrylate salts on the setting behavior of ultra-low cement (ULC) refractory castables was addressed in this paper, with special attention to the interactions of such chemical additives with the cement particles in the aqueous medium. Rheological experiments, electrical conductivimetry, temperature measurements, SEM, X-ray diffractometry and mechanical tests were performed to characterize the cement-based compositions prepared in this work. In spite of its strong inhibiting effect on the precipitation of cement hydrated phases, sodium citrate was found to induce the earlier setting of ULC refractory castables, due most likely to the formation of a gelled phase between the citrate anions and the ions originated from the dissolution of cement particles. The most probable reasons for the formation of this unexpected gelled phase are discussed in this paper.

Structural study of LaNixFe1−xO3 prepared from precursor salts

LaNiO3, LaFeO3 and their solid solution LaNi0.3Fe0.7O3 have been prepared using acetate and citrate salts as precursors. The decomposition of organic substances were obtained by calcination in mild conditions. A detailed discussion of the structural and microstructural changes of these materials due to thermal treatments is proposed by means of X-ray diffraction, microraman spectroscopy, and scanning electron microscopy studies. Moreover, the local distortion of the perovskite structure determining the second order transition in these perovskites has been evidenced by microraman spectroscopy. Indeed, this technique has been shown to be powerful to characterize the local coordination of the metals, that is possibly a critical parameter in their chemical activity.

Influence of Urine pH and Citrate Concentration on the Upper Limit of Metastability for Calcium Phosphate

We determined the effects on the urine upper limit of metastability for calcium phosphate of citrate concentration and pH, and achievement of the upper limit of metastability by adding calcium or phosphate. The citrate concentration in aliquots of 24-hour urine samples from normal males without a history of kidney stones was increased. The upper limit of metastability was determined by the point of visible crystal formation, as confirmed by increased optical density at 620 nm. when calcium or pH was increased. In additional experiments the upper limit of metastability was determined by adding calcium or phosphate at pH 5.9 and 6.4. Regardless of how the upper limit of metastability was achieved increasing the citrate concentration increased the former value by about 0.4 units per mM. citrate per l. The upper limit of metastability achieved in a given urine sample by adding phosphate or calcium did not differ. Increasing urine pH increased the upper limit of metastability. Treatment with alkaline citrate salts may decrease stone formation via an increase in calcium phosphate upper limit of metastability by increasing urine citrate and by directly affecting increased pH.

Citrate and mineral metabolism: kidney stones and bone disease.

Citrate is a weak acid that is formed in the tricarboxylic acid cycle or that may be introduced with diet. In the present paper all the mechanisms involved in intestinal absorption, renal handling and modulation of citrate will be reviewed. The evaluation of plasma citric acid is scarcely used in the diagnosis of human diseases. On the contrary urinary citrate excretion is a common tool in the differential diagnosis of kidney stones, renal tubular acidosis and it plays also a role in bone diseases. Therefore the importance of hypocitraturia will be reviewed with regard to bone mass, urine crystallization and urolithiasis. Finally particular attention will be paid to the incidence of hypocitraturia and to the therapy with citrate salts, both in kidney stone disease and in osteopenia.

Pyrolysis as a technique for separating heavy metals from hyperaccumulators. Part I: Preparation of synthetic hyperaccumulator biomass

Phytoremediation involves removing metals from soil or water for environmental reasons and phytomining implies extraction of metals from soils rich in metal content, using hyperaccumulators for economic gain. “Synthetic hyperaccumulator biomass” (SHB) was prepared to mimic the metal concentration and/or chemistry found in actual hyperaccumulators. The purpose for developing a technique to produce SHB was to prepare sufficient quantities of samples for use in lab-scale and pilot-scale pyrolysis experiments. Bench scale experiments were conducted at 27°C to incorporate metals like Ni, Zn, Cu, Co, and Cr into 3 g of SHB (milled corn stover) using metal acetate and metal citrate salt solutions. Two parameters, namely concentration of metal salt and soaking time were studied. Suitable acetate and/or citrate feed concentrations and soaking times were then selected for preparing the SHB, containing a particular heavy metal, for lab-scale and pilot-scale pyrolysis experiments. For the lab-scale pyrolysis experiments, 160 g of the SHB was prepared using the five heavy metal acetate and citrate feeds. About 500 g of the SHB was prepared for the pilot-scale experiments using the Ni, Zn, and Cu acetate feeds. Except for lab-scale/Cu acetate feed (6% higher), lab-scale/Cr acetate feed (20% higher), lab-scale/Ni citrate feed (8% lower), and pilot-scale/Cu acetate feed which was 2.2 times higher than the literature value, concentration of metal in the other nine types of SHB prepared for the lab-scale and pilot-scale pyrolysis experiments was within the hyperaccumulator metal concentration ranges found in the literature. The final goal of this work, which is presented in a series of four parts, is to demonstrate the use of pyrolysis as a first step towards the recovery of heavy metals from hyperaccumulators used for phytoremediation or phytomining.

Urinary citrate excretion in patients with renal stone: roles of leucocyte ATP citrate lyase activity and potassium salts therapy

Background: Hypocitraturia is a major metabolic abnormality in rural Northeast Thais with renal stones. These people also have low serum and urinary potassium and consume a high carbohydrate and low fat diet, which together might influence the intracellular metabolism and urinary excretion of citrate. Methods: In Study A, we measured plasma and urinary chemistries and assayed leucocyte ATP citrate lyase (ACL) activity in 30 normal urban control subjects (Group A1) and 30 rural renal stone patients (Group A2) in Northeast Thailand. Some of the subjects from both groups were also used to evaluate the intake of carbohydrate, protein and fat. In Study B, we examined the effects of potassium salts therapy with another group of 30 rural renal stone patients: Group B1 ( n=15) treated with potassium chloride and Group B2 ( n=15) with potassium-sodium citrate (with an aim to achieve 42 mEq potassium, 21 mEq sodium and 62 mEq citrate per day for 1 month). Results: In Study A, the leucocyte ACL activity of Group A1 was much lower than that of Group A2 (3.2±0.7 vs. 9.3±3.8 μmol acetylhydroxamate/mg protein/30 min, p<0.0001). The plasma potassium, urinary excretions of potassium and citrate in Group A1 were higher than in Group A2. When data of the two groups were combined, urinary citrate excretion was inversely correlated with leucocyte ACL activity ( r=0.6783, p<0.001). While the dietary protein intake did not differ between Groups A1 and A2, the carbohydrate intake by Group A1 was significantly lower (65.2±7.9% vs. 83.1±2.9%, p<0.01) and fat higher (21.0±6.4% vs. 6.2±4.1%, p<0.002) than Group A2. After treatment with potassium chloride (Group B1), only the potassium was increased ( p<0.001), while those treated with potassium-sodium citrate (Group B2) experienced a significant increase in urinary pH ( p<0.002), potassium ( p<0.001) and citrate ( p<0.001), and a decrease in leucocyte ACL activity ( p<0.001). Conclusions: Compared to normal subjects, renal stone patients have low urinary citrate excretion with high leucocyte ACL activity. In Northeast Thailand, low potassium status and a high carbohydrate and low fat diet may cause the increased ACL activity. However, hypokaliuria, hypocitraturia and high leucocyte ACL activity can be corrected by potassium-sodium citrate salt therapy.

Formation of transition metal–doxorubicin complexes inside liposomes

Doxorubicin complexation with the transition metal manganese (Mn 2+) has been characterized, differentiating between the formation of a doxorubicin–metal complex and doxorubicin fibrous-bundle aggregates typically generated following ion gradient-based loading procedures that rely on liposome encapsulated citrate or sulfate salts. The physical and chemical characteristics of the encapsulated drug were assessed using cryo-electron microscopy, circular dichroism (CD) and absorbance spectrophotometric analysis. In addition, in vitro and in vivo drug loading and release characteristics of the liposomal formulations were investigated. Finally, the internal pH after drug loading was measured with the aim of linking formation of the Mn 2+ complex to the presence or absence of a transmembrane pH gradient. Doxorubicin was encapsulated into either 1,2-dimyristoyl- sn-glycero-3-phosphocholine (DMPC)/cholesterol (Chol) or 1,2-distearoyl- sn-glycero-3-phosphocholine (DSPC)/Chol liposomes, where the entrapped salts were citrate, MnSO 4 or MnCl 2. In response to a pH gradient or a Mn 2+ ion gradient, doxorubicin accumulated inside to achieve a drug-to-lipid ratio of approximately 0.2:1 (wt/wt). Absorbance and CD spectra of doxorubicin in the presence of Mn 2+ suggested that there are two distinct structures captured within the liposomes. In the absence of added ionophore A23187, drug loading is initiated on the basis of an established pH gradient; however, efficient drug uptake is not dependent on maintenance of the pH gradient. Drug release from DMPC/Chol is comparable regardless of whether doxorubicin is entrapped as a citrate-based aggregate or a Mn 2+ complex. However, in vivo drug release from DSPC/Chol liposomes indicate less than 5% or greater than 50% drug loss over a 24-h time course when the drug was encapsulated as an aggregate or a Mn 2+ complex, respectively. These studies define a method for entrapping drugs possessing coordination sites capable of complexing transition metals and suggest that drug release is dependent on lipid composition, internal pH, as well as the nature of the crystalline precipitate, which forms following encapsulation.

Antibacterial activity of citrate and acetate

OBJECTIVE: We evaluated citrate salt, acetate salt, and their combinations for antibacterial activity against a sample of common pathogens. METHODS: Bacterial suspensions were added to serial microdilutions of the salts in broth, with final cell concentrations of 10 4–5 colony-forming units per milliliter. After overnight incubation at 35°C, the minimum inhibitory concentration was recorded. Bactericidal activity was screened by quantitative subcultures from the minimum inhibitory concentration dilution. RESULTS: Citrate salt was active against gram-positive species and Candida albicans but showed little activity against gram-negative species; acetate salt showed the opposite results. Their combination did not show synergism or antagonism. CONCLUSION: It may be feasible to take advantage of the different antibacterial spectra of these two agents and combine them for possible application such as food or medical preservative agents.

A simple LC method with UV detection for the analysis of creatine and creatinine and its application to several creatine formulations

The objective of this study was to develop a simple and sensitive LC method for the determination of creatine and creatinine in various creatine supplement formulations. The chromatographic system comprised of a LC-600 pump, SCL-6B system controller, and SPD-6AV detector (Shimadzu, Japan). The mobile phase consisted of 0.045 M ammonium sulfate in water. The chromatographic separation was achieved at ambient temperature on a Betabasic C-18 column (250×4.6 mm, Keystone Sci.). The flow rate was maintained at 0.75 ml/min and effluents are monitored at 205 nm. 4-(2-Aminoethyl)benzene sulfonamide was used as an internal standard (IS). This method required less than 7 min of chromatographic time. The standard curves were linear over the concentration range of 1–100 μg/ml for creatine and 2–100 μg/ml for creatinine, respectively. The relative standard deviations (RSD) for the within-day and day-to-day precision for creatine were within 1.0–4.6 and 2.2–4.7%, respectively. The RSD for the accuracy of creatine assay was in the range of 2.4–4.7%. The RSD values for the within-day precision, day-to-day precision and accuracy for creatinine validation were 1.7–4.4, 2.3–5.4 and 2.4–4.8%, respectively. This method was used to determine: (i) the creatine concentration in various marketed products; (ii) saturated solubility of various creatine salts; and (iii) stability of creatine in aqueous solution. In conclusion, a simple and sensitive LC method with UV detection was developed for the simultaneous determination of creatine and creatinine in formulations. Di-creatine citrate salt showed a higher aqueous solubility (at 25 °C) as compared to creatine and creatine monohydrate. Some of the over-the-counter (OTC) products tested contained a very low level of creatine in contrast to their label claim. Substantial conversion of creatine into creatinine was noticed in liquid formulation.

Recovery of metal ions from spent solutions used to electrodeposit magnetic materials

Abstract The feasibility of using electrodialysis to extract metal ions such as cobalt and nickel from spent electroplating baths employing citrate salts was examined. Modeling of metal-citrate speciation in electrolytes was initially used to identify conditions under which such a separation process might be possible. The most promising separation scheme identified in these studies required acidification of the electrolyte to de-complex the metal ions from citrate, followed by extraction of the metal ions through a cation exchange membrane. A number of commercially available cation exchange membranes have been shown to be suitable for the recovery of Co 2+ , Ni 2+ and Cu 2+ ions from citrate-based electrolytes. In terms of current efficiency, Nafion 117 was found to be the most suitable membrane material for metal ion recovery from citrate electrolytes. The rates of transfer of anionic metal citrate complexes through various anion exchange membranes were found to be low compared with other anions and the extraction of metal ions in this manner therefore does not appear feasible. Typically, metal ion separation factors of near unity were observed for both the Cu–Ni and Cu–Co citrate baths, indicating that is it generally not possible to achieve significant separation of divalent metal ions using commercially available cation exchange membranes.

Citrate therapy for polycystic kidney disease in rats

Few treatments are available to slow the progression to renal failure in autosomal dominant polycystic kidney disease (PKD). In an animal model of PKD, the male heterozygous Han:SPRD rat, intake of a solution of potassium citrate plus citric acid (KCitr) from age one to three months prevented a decline in glomerular filtration rate (GFR). The present study tested whether this beneficial effect is sustained and explored handling of citrate and ammonia in normal and cystic kidneys. Rats were provided with tap water or citrate solutions to drink, and clearance and survival studies were performed. The GFRs of rats with PKD that consumed KCitr from one month of age were normal at six months of age, while those of their counterparts on water were about one third of normal. Long-term KCitr treatment extended the average life span of rats with PKD from 10 to 17 months. Compared with normal rats, water-drinking rats with PKD had higher plasma [citrate], renal cortical [citrate], and fractional excretion of citrate, and lower rates of renal citrate consumption, ammonia synthesis, and ammonia excretion. Cortical PNH3 was not elevated in cystic kidneys. Intake of Na3 citrate/citric acid solution or K3 citrate solution, but not ammonium citrate/citric acid solution, prevented a decline in GFR in three-month-old rats with PKD. Rats with PKD show abnormal renal handling of citrate and ammonia. Citrate salts that have an alkalinizing effect preserve GFR and extend survival.

The disposition of pyrantel in the gastrointestinal tract and effect of digesta flow rate on the kinetic behaviour of pyrantel in the pig

Pigs consuming a diet with slow digesta transit time were orally administered with molar equivalent doses of pyrantel as the citrate and pamoate salt. At appropriate intervals pigs were killed and the quantitative-time distribution of pyrantel throughout the gut contents was determined. Compared with the citrate, there appeared to be greater quantities of the less soluble pamoate salt in the small and large intestine. An additional group of pigs fed on diets with “slow” or “fast” digesta transit time were orally treated with molar equivalent amounts of pyrantel as the citrate and pamoate salt and the respective kinetic disposition of pyrantel in peripheral plasma and quantitative excretion in faeces was determined. The diet type had little effect on pyrantel availability after administration of the less soluble pamoate salt. However, the maximum concentration of pyrantel in plasma was lower and there appeared to be greater quantities of pyrantel retained in the gut and excreted in faeces when the citrate salt was orally administered to pigs fed the “fast” compared to the “slow” diet. Since it is the quantity of pyrantel contained in the gut lumen which is believed to affect efficacy against gastrointestinal parasites, greater efficacy with this anthelmintic should be obtained when pigs are consuming a high fibre diet.

Effect of sulfate and citrate salts on derivatization of amylose and amylopectin during hydroxypropylation of corn starch

Common corn starch was modified in 0.56 M sodium sulfate solution and in 0.31 M potassium citrate solution. It was found that about 1.8 times the amount of reagent (propylene oxide) was needed to get a same molar substitution (MS) when potassium citrate was used. Hydroxypropylated starches were fractionated on a size-exclusion column to separate amylose from amylopectin, and MS values of the whole starch, the amylose, and the amylopectin were determined. In all preparations, amylose was derivatized to a greater extent than was amylopectin. The data indicate that, with common corn starch: (1) the greater the overall derivatization, the greater was the preference for derivatization of amylose; and (2) the preference for amylose derivatization was greater for corn starch modified in potassium citrate solution than in sodium sulfate solution when the MS values for the two preparations were essentially the same.

Development and validation of an HPLC assay for fentanyl, alfentanil, and sufentanil in swab samples

A high performance liquid chromatography (HPLC) method for the assay of fentanyl citrate, alfentanil hydrochloride, and sufentanil citrate swab samples was developed and validated in order to control a cleaning procedure. The swabbing procedure involved Super POLX 1200 wipers moistened with water. The assay employed extraction of swabs with water and analysis by isocratic, reversed-phase, HPLC with varying ultraviolet (UV) detection for desired sensitivity, depending on the analyte. The method was shown to be selective and linear from the limits of quantitation (0. 10, 0. 20, and 0. 15 μg/swab for fentanyl citrate, alfentanil, and sufentanil, respectively) to over three times these concentrations. The assay limits (detection levels) per swab area were set at least at 0.2% of the concentrations of the actives in the drug products (0.02, 0. 10, and 0. 10 μg/swab or approximately 0.03, 0.02, and 0.2% for fentanyl citrate, alfentanil, and sufentanil, respectively). It should be noted that all active concentrations listed in this work were calculated based on the salt form concentration for fentanyl (citrate salt) and the free base forms for alfentanil and sufentanil. No reference standard was available for alfentanil hydrochloride and sufentanil citrate. Drug product was used instead throughout this study.