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PubMed2004

pH stability of ophthalmic solutions.

BACKGROUND: In this study, we evaluated the pH value of 17 ophthalmic solutions, and we investigated whether the pH of these solutions changed over time after the bottle was opened. METHODS: Fifteen bottles of each type of solution were chosen at random from different production lots. A 0.05-ml increment was taken from each bottle and was measured daily using a micropH 2002 Crison pH-meter over a period of 30 days. RESULTS: The results revealed differences between the pH values of the solutions; nine solutions presented pH values within ocular comfort range and eight solutions presented pH values between 3.5 and 6.4. Ten solutions presented nonstatistically significant variations over time (p > 0.01) and seven solutions presented isolated but statistically significant variations. CONCLUSIONS: We may assume that the nine solutions with pH values within the ocular comfort range will not produce initial discomfort. The solutions with acid pH values will produce initial discomfort. The solutions with nonstatistically significant pH variations over 30 days in relation to their initial pH values presented great stability.

Drug Stability↗
PubMed2006

Thermodynamic studies of molecular interactions in aqueous alpha-cyclodextrin solutions: application of McMillan-Mayer and Kirkwood-Buff theories.

Osmotic vapor pressure and density measurements were made for aqueous alpha-cyclodextrin (alpha-CD) solutions in the temperature range between 293.15 and 313.15 K. The experimental osmotic coefficient data were used to determine the corresponding activity coefficients and the excess Gibbs free energy of solutions. Further, the activity data obtained at different temperatures along with the enthalpies of dissolution (reported in the literature) were processed to obtain the excess enthalpy and excess entropy values for the solution process. The partial molar entropies of water and of alpha-cyclodextrin were calculated at different temperatures and also at different concentrations of alpha-CD. Using the partial molar volume data at infinite dilution, the solute-solvent cluster integrals were evaluated which yielded information about solute-solvent interactions. The application of McMillan-Mayer theory of solutions was made to obtain osmotic second and third virial coefficients which were decomposed into attractive and repulsive contributions to solute-solute interactions. The second and third osmotic virial coefficients are positive and show minimum at 303.15 K. The Kirkwood-Buff (KB) integrals G(ij), defined by the equation G(ij) = f(infinity)0 (g(ij)- 1)4pir(2) dr, have been evaluated using the experimental osmotic coefficient (and hence activity coefficient) and partial molar volume data. The limiting values of KB integrals, G(ij)(0) are compared with molecular interaction parameters (solute-solute i.e., osmotic second virial coefficient) obtained using McMillan-Mayer theory of solutions. We found an excellent agreement between the two approaches.

Chemistry, Physical↗
PubMed1998

Characterization of frozen aqueous solutions by low temperature X-ray powder diffractometry.

PURPOSE: A low temperature X-ray powder diffractometric (XRD) technique has been developed which permits in situ characterization of the solid-state of solutes in frozen aqueous solutions. METHODS: A variable temperature stage, with a working temperature range of -190 to 300 degrees C, was attached to a wide-angle XRD. The stage was calibrated with a sodium chloride-water binary system. RESULTS: When aqueous nafcillin sodium solution (22% w/w) was frozen, eutectic crystallization of the solute was not observed. However, annealing at -4 degrees C, caused crystallization of the solute. With increasing annealing time, there was a progressive increase in the crystallinity of the solute. Studies were carried out with sodium nafcillin solutions ranging in concentration from 20 to 50% w/w. The solid-state of the phase crystallizing from solution was independent of the solute concentration. Next, solutions of mono- and disodium hydrogen phosphate were individually frozen. Only the latter crystallized as the dodecahydrate (Na2HPO4.12H2O). However when an aqueous buffer mixture of mono- and disodium hydrogen phosphate was frozen, the former inhibited the crystallization of the latter. CONCLUSIONS: Since freezing of solutions is the first step in lyophilization, the XRD technique can provide a mechanistic understanding of the alterations in solid-state that occur during freeze-drying. DSC has so far been the technique of choice to study frozen systems. The advantage of XRD is that it not only permits unambiguous identification of the crystalline solid phase(s), but it also provides information about the degree of crystallinity. While overlapping thermal events are difficult to interpret in DSC, XRD does not suffer from such a limitation.

Freezing↗
PubMed1997

Ionization and solubilization of 4 alkyl benzoic acids and 4 alkyl anilines in sodium taurodeoxycholate solutions.

PURPOSE: The aqueous solubility and the extent of solubilization and ionization constant in sodium taurodeoxycholate (NaTDC) solutions of a series of benzoic acid and aniline derivatives were measured as a basis to characterize and thereby help predict the nature of the interaction of drugs with bile aggregates. METHODS: The aqueous solubility and the solubilization of two series of compounds, 4-alkyl benzoic acids and 4-alkyl anilines, was measured as a function of NaTDC in 0 and 150 mM NaCl. The ionization constants were determined in water and in 50 mM NaTDC at sodium chloride concentration of 0, 75 and 150 mM by spectrophotometric titration. The diffusion coefficients of NaTDC and the solutes were measured by pulsed-field gradient spin echo NMR spectroscopy. RESULTS: The aqueous solubilities decreased with increasing alkyl chain length in both series, and the aniline derivatives had larger solubilities than the benzoic acid derivatives. The number of moles of solute solubilized per mole of bile salt ranged from 0.17 to 0.31 for the benzoic acid derivatives and from 1.3 to 3.0 for the aniline derivatives. The pKa values of the benzoic acid derivatives in the presence of NaTDC were higher relative to the controls, and the difference in the pKa (delta pKa,obs) increased with increasing chain length. With the aniline derivatives, the pKa values were also shifted to higher values in NaTDC relative to the control but only in the absence of salt. The presence of the solute caused a decrease in the diffusion coefficient of NaTDC, and the diffusion coefficients of the solutes decreased with increasing alkyl chain length. With the hexyl derivative, the diffusion coefficient of the solute was smaller than the diffusion coefficient of the bile salt. The chemical shift of the protons attached to carbon 18 and 19 of the salt were decreased to a greater extent in the presence of the solutes than the protons attached to carbon 26. CONCLUSION: Both the solubilization and ionization behavior of solutes were affected by the presence of bile salt aggregates. The surface potential and effective polarity of NaTDC aggregates were found to be dependent on the alkyl chain length for these two homologous series of solutes. The solubilization ratio was largely independent of alkyl chain length, but the unitary partition coefficient was dependent on both alkyl chain length as well as ionization state. The derivatives reduced the diffusivity of the micelles suggesting the formation of larger size aggregates and the solutes (hexyl derivatives) appear to favor association with the larger sized aggregates. The phenyl ring of the solutes appears to be oriented parallel to the plane of the steroid frame with preferential positioning near the hydrophobic rings.

Aniline Compounds↗
PubMed2003

A comparison of hetastarch and peritoneal dialysis solution for intraperitoneal chemotherapy delivery.

AIM: Intraperitoneal chemotherapy administration results in high drug concentration locally with low systemic toxicity. We compared the pharmacokinetics of paclitaxel infused intraperitoneally in two isotonic carrier solutions, 1.5% dextrose peritoneal dialysis solution (peritoneal dialysis solution) and hetastarch (6% hydroxyethyl starch), a high molecular weight solution. METHODS: Twenty patients with peritoneal carcinomatosis were randomized into one of two groups to receive early postoperative intraperitoneal chemotherapy with paclitaxel for 5 consecutive days following cytoreductive surgery. One group (8 patients) received paclitaxel in one litre of peritoneal dialysis solution; the other group (12 patients) received paclitaxel in one litre of hetastarch. Samples of peritoneal fluid and venous blood were taken during the 23 h dwell time. Volumes of chemotherapy solution were recorded and concentrations of paclitaxel determined by high performance liquid chromatography. RESULTS: Hetastarch clearance from the peritoneal cavity was reduced when compared to peritoneal dialysis solution. The mean volume of fluid remaining in the peritoneal cavity at 23 h was 900 ml +/-373.7 (SD) with hetastarch, and 285 ml (+/-157.5) with peritoneal dialysis solution (P=0.0022). The mean total amount of paclitaxel in the peritoneal cavity at 23 h was 2.597 mg (+/-1.57) with hetastarch and 0.772 mg (+/-0.667) with peritoneal dialysis solution (P=0.0152). CONCLUSION: These data show that hetastarch increased the exposure of peritoneal surfaces to paclitaxel by increasing the volume of solution with no decrease in drug concentration. Residual tumour cells within the peritoneal cavity may show an increased response to paclitaxel with hetastarch as a carrier solution.

Adult↗
PubMed1998

Stability of vancomycin in an extemporaneously compounded ophthalmic solution.

The stability of vancomycin 31 mg/mL (as the hydrochloride) in an artificial tears solution at -10, 4, 25, and 40 degrees C was studied. Vancomycin power was reconstituted with sterile water for injection to a concentration of 50 mg/mL. Artificial tears solution containing 0.3% hydroxypropyl methylcellulose, 0.1% dextran 70, 0.01% benzalkonium chloride, and 0.05% edetate disodium was used to produce a final concentration of 31 mg/mL. Triplicate solutions for each storage temperature and sampling time were prepared. The solutions were stored at -10, 4, 25, and 40 degrees C. Samples were taken initially and at 3, 7, 10, 21, 30, 45, and 60 days for visual inspection and analysis by high-performance liquid chromatography. All solutions remained clear and colorless at -10, 4, and 25 degrees C throughout the study period. By day 3, crystalline particles formed in the solutions stored at 40 degrees C. No substantial change in pH was observed at any time. At -10 degrees C, the solutions retained more than 90% of their initial vancomycin concentrations throughout the study period. The solutions retained a mean of at least 90% of the initial drug concentration for 21 days at 4 degrees C and for 7 days at 25 degrees C. For the solutions stored at 25 or 40 degrees C, less than 85% of the initial vancomycin concentration remained after 10 and 3 days, respectively. Vancomycin 31 mg/mL (as the hydrochloride) in an artificial tears solution was stable for 45 days at -10 degrees C, 10 days at 4 degrees C, and 7 days at 25 degrees C in the tears solution's original container.

Anti-Bacterial Agents↗
PubMed2001

Oxygen transport dynamics of acellular hemoglobin solutions in an isovolemic hemodilution model in swine.

BACKGROUND: One of the perceived advantages of a hemoglobin-based blood substitute is the provision of oxygen-carrying capacity. Although the hemodynamic response to the infusion of acellular hemoglobin solutions has been extensively studied, less is known about the oxygen transport dynamics of such solutions. We hypothesized that acellular hemoglobin solutions are useful oxygen carriers in anemic states and that higher P50 solutions transport O2 more efficiently than low P50 solutions. We sought to quantify O2 transport dynamics of hemoglobin solutions in an isovolemic hemodilution model in swine. METHODS: Eighteen swine were anesthetized, ventilated, and instrumented for hemodynamic measurements and for withdrawal of arterial and mixed venous blood. The swine were randomized into three groups and progressively bled from an initial hematocrit (Hct) of 30% to Hcts of 19%, 13%, and 8% using isovolemic exchange with pyridoxalated hemoglobin polyoxyethylene conjugate (PHP, n = 6); an identical hemoglobin solution without the pyridoxalation, resulting in a low P50 solution (POE-Hb, n = 6); or an osmotically similar control solution of pentastarch (PS, n = 6). Hemodynamic measurements, arterial and mixed venous O2 content, and O2 extraction ratio (ER), were determined in whole blood (WB), the red blood cell (RBC) phase, and the plasma phase utilizing a compartmentalized approach. RESULTS: Mean pulmonary arterial pressure was higher with hemodilution in the PHP and POE-Hb groups than in the PS group (p < 0.05). Cardiac index increased with hemodilution in all groups, but was significantly less than the cardiac index in the PS group at Hcts = 19% and 13%. Oxygen delivery and consumption were maintained at all hematocrits at baseline levels in the PHP and POE-Hb groups, but O2 delivery was significantly decreased in the PS group at Hct = 8% (p < 0.05 for PS vs. baseline and p < 0.05 for PHP and POE-Hb vs. PS). Oxygen extraction ratio increased with progressive hemodilution in both the RBC hemoglobin and plasma phases to a maximum of 39% for PHP and 36% for POE-Hb at Hct = 8%. The percent contribution from the plasma phase to total oxygen delivery and consumption likewise increased with hemodilution to maximum values of 52.7% (PHP) and 68.2% (POE-Hb) for delivery and 40.9% (PHP) and 39.3% (POE-Hb) for consumption. CONCLUSION: Acellular hemoglobin solutions provide a significant contribution to O2 delivery and consumption, particularly in severe anemia, in this model of isovolemic exchange. The differences in the P50 of the two hemoglobin solutions do not appear to significantly influence oxygen dynamics over the range of hematocrits studied.

Animals↗
PubMed2006

Efficacy of multipurpose solutions for rigid gas permeable lenses.

The use of multipurpose solutions for cleaning and disinfecting rigid gas permeable lenses has replaced single purpose solutions, but there are no reports of the efficacy of these multipurpose solutions, or of the effects of storage conditions on their disinfecting capacities. This study investigated activity against four bacterial and two fungal species, and the effects of storage in a refrigerator, at room temperature, at elevated temperature in both dry and humid conditions and with exposure to sunlight. The disinfecting solutions were challenged with the micro-organisms initially upon opening and then at 2-weekly intervals up to 12 weeks after being stored under the different conditions. Solutions were opened daily to simulate use. One solution failed to meet Food and Drug Administration (FDA) criteria to reduce numbers of bacteria by three log dilutions and of fungi by one log dilution. Storage reduced activity of all solutions over the 12-week period, but not below the requirements of the FDA. Storage in the refrigerator tended to reduce disinfecting capacity more quickly. Multipurpose solutions for rigid gas permeable (RGP) lenses lose activity over the 3 months recommended time of use but remain satisfactory for use over this time in the conditions tested. Practitioners need to remind patients to replace their solutions regularly and should advise against storage in the refrigerator. Multipurpose solutions for RGP lenses have simplified cleaning and disinfecting processes and the current formulations have improved disinfecting capacity compared to former disinfecting solutions, which is particularly important for wearers of orthokeratology lenses.

Anti-Infective Agents↗
PubMed2005

The clearance of protein-bound solutes by hemofiltration and hemodiafiltration.

BACKGROUND: Hemofiltration in the form of continuous venovenous hemofiltration (CVVH) is increasingly used to treat acute renal failure. Compared to hemodialysis, hemofiltration provides high clearances for large solutes but its effect on protein-bound solutes has been largely ignored. METHODS: Standard clinical systems were used to remove test solutes from a reservoir containing artificial plasma. Clearances of the protein-bound solutes phenol red (C(PR)) and indican (C(IN)) were compared to clearances of urea (C(UREA)) during hemofiltration and hemodiafiltration. A mathematical model was developed to predict clearances from values for plasma flow Q(p), dialysate flow Q(d), ultrafiltration rate Q(f), filter size and the extent of solute binding to albumin. RESULTS: When hemofiltration was performed with Q(p) 150 mL/min and Q(f) 17 mL/min, clearance values were C(PR) 1.0 +/- 0.1 mL/min; C(IN) 3.7 +/- 0.5 mL/min; and C(UREA) 14 +/- 1 mL/min. The clearance of the protein-bound solutes was approximately equal to the solute-free fraction multiplied by the ultrafiltration rate corrected for the effect of predilution. Addition of Q(d) 42 mL/min to provide HDF while Q(p) remained 150 mL/min resulted in proportional increases in the clearance of protein-bound solutes and urea. In contrast, the clearance of protein-bound solutes relative to urea increased when hemodiafiltration was performed using a larger filter and increasing Q(d) to 300 mL/min while Q(p) was lowered to 50 mL/min. The pattern of observed results was accurately predicted by mathematical modeling. CONCLUSION: In vitro measurements and mathematical modeling indicate that CVVH provides very limited clearance of protein-bound solutes. Continuous venous hemodiafiltration (CVVHDF) increases the clearance of protein-bound solutes relative to urea only when dialysate flow rate and filter size are increased above values now commonly employed.

Acute Kidney Injury↗
PubMed1995

Albumin-based solutions for peritoneal dialysis: investigations with a rat model.

To evaluate albumin, an osmotic agent for peritoneal dialysis, the peritoneal fluid and solute transport were investigated during a 4-h single cycle peritoneal dialysis with albumin-based dialysis solutions. Two different albumin solutions were used in 15 normal Sprague-Dawley rats: isotonic 7.5% albumin solution (ADS 1, n = 7) and a combined 7.5% albumin and 1.35% glucose solution (ADS 2; n = 8). A standard 1.36% Dianeal solution was used to provide control values (n = 6). The rate of the intraperitoneal volume change (Qv) was positive during the initial 90 min with ADS 2 and during the initial 60 min with Dianeal 1.36% solution but negative with ADS 1. The peritoneal bulk flow reabsorption rate, Qa, was similar in all three groups. The estimated rate of transcapillary ultrafiltration (Qu = Qv + Qa) was positive with all three solutions throughout the dialysis. With ADS 1, Qu increased gradually during the initial 90 min and then remained stable, but it decreased with ADS 2 and Dianeal 1.36% solution. Qu with ADS 2 did not differ from that with Dianeal 1.36% solution during the initial 60 min, but it was significantly higher during the latter part of dialysis. The value of Qu during the last 2 h of dialysis was 0.026 +/- 0.010 and 0.025 +/- 0.009 ml/min with ADS 1 and ADS 2, respectively, and it was significantly higher than that with Dianeal 1.36% solution (0.005 +/- 0.007 ml/min; p < 0.017).(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1997

PGE1, dexamethasone, U-74389G, or Bt2-cAMP as an additive to promote protection by UW solution in I/R injury.

A method to reduce ischemia-reperfusion (I/R) injury can be an important criterion to improve the preservation solution. Although University of Wisconsin solution (UW) works as a lung preservation solution, its attenuation effect on I/R injury has not been investigated. We attempted to determine whether, by adding various protective agents, modified UW solutions will enhance the I/R attenuation by UW. We examined the I/R injury in an isolated rat lung model. Various solutions, e.g., physiological salt solution (PSS), UW, and modified UW solutions containing various protective agents such as prostaglandin E1, dexamethasone, U-74389G, or dibutyryl adenosine 3',5'-cyclic monophosphate were perfused individually to evaluate the I/R injury. Isolated rat lung experiments, with ischemia for 45 min, then reperfusion for 60 min, were conducted in a closed circulating system. Hemodynamic changes, lung weight gain (LWG), capillary filtration coefficient (Kfc), protein content of lavage fluid, concentration of cytokines, and lung histopathology were analyzed. Results showed that the acute I/R lung injury with immediate permeability pulmonary edema was associated with an increase in tumor necrosis factor-alpha (TNF-alpha) production. A significant correlation existed between TNF-alpha and Kfc (r = 0.8, P < 0.0001) and TNF-alpha and LWG (r = 0. 9, P < 0.0001), indicating that TNF-alpha is an important cytokine modulating early I/R injury. Significantly lower levels of Kfc, LWG, TNF-alpha, and protein concentration of lung lavage (P < 0.05) were found in the UW-perfused group than in the control group perfused with PSS. Modified UW promoted the protective effect of UW to further decrease Kfc, LWG, and TNF-alpha (P < 0.05). Histopathological observations also substantiated this evidence. In the UW+U-74389G group, bronchial alveolar lavage fluid contained lowest protein concentration. We conclude that the UW solution attenuates I/R injury of rat lung and that the modified UW solutions further enhance the effect of UW in reducing I/R injury. Among modified solutions, UW+U-74389G is the best. Further investigation of the improved effects of the modified UW solutions would be beneficial in lung transplantation.

Adenosine↗
PubMed1999

Tolerability and safety of 0.1% diclofenac plus 0.3% tobramycin fixed-dose ophthalmic solution: a randomized, comparative, controlled study in healthy volunteers.

The purpose of this double-blind, observer-masked, randomized, crossover trial was to compare the tolerability and safety of a fixed-dose ophthalmic solution of 0.3% tobramycin plus 0.1% diclofenac versus Tobrex (tobramycin sulfate ophth) and Voltaren (diclofenac sodium). Control treatments included a saline solution and a control solution of 0.3% tobramycin prepared by Alcon Cusí. Ten healthy volunteers received three consecutive instillations of 1 drop of a given ophthalmic solution at 08:00, 11:00 and 14:00 h to the same eye; after a washout period of 18 h, the next ophthalmic solution was tested according to a randomized sequence. Occurrence, intensity, and duration of ocular irritation and conjunctival hyperemia at baseline and after the three instillations were recorded. Slit lamp biomicroscopy examination, measurement of intraocular pressure (IOP) changes, visual acuity, and examination of the fundus of the eye were performed after each third instillation by an ophthalmologist. Side effect incidence and patient and investigator opinions were also recorded. Results showed that Voltaren instillation induced statistically significant ocular irritation (p = 0.0077); the remaining ophthalmic solutions tested caused no ocular irritation (Physiological Saline Braun, p = 0.9808; Tobrex, p = 0.8826; control 0.3% tobramycin solution, p = 0.8327; and 0.1% diclofenac plus 0.3% tobramycin, p = 0.5399). None of the ophthalmic solutions tested caused severe conjunctival hyperemia. Analysis of the sum of conjunctival parameters of both eyes for all ophthalmic solutions studied showed no statistically significant differences (p = 0.4688). Moderate superficial punctate keratitis was observed after instillation of Voltaren and of 0.1% diclofenac plus 0.3% tobramycin (1 subject each) that spontaneously resolved within 2 days. Slit lamp biomicroscopy, visual acuity and IOP values showed no statistically significant changes. No systemic side effects related to the study treatments were recorded. In conclusion, the ophthalmic solution containing 0.1% diclofenac plus 0.3% tobramycin was well tolerated under the study conditions. Its tolerability was equivalent to that of Braun physiological saline, Tobrex and a control 0.3% tobramycin solution and was better than that of Voltaren.

Adolescent↗
PubMed1988

Effects of the high K+/Na+ deficient solution on mechanical response and wet weight of tissue in vas deferens and seminal vesicle in guinea-pig.

In the present experiments, we investigated contractions of guinea-pig vas deferens or seminal vesicle in various kinds of high K+ solution. The vas deferens showed a phasic contraction followed by a tonic one in hyperosmotic 65 mM KCl (hyper-65K+), isosmotic 60 mM or 120 mM KCl solution. However, isosmotic 154 mM KCl (iso-154K+) solution induced a large phasic contraction followed by a gradual relaxation. Applications of the high K+ solutions to the preparation of seminal vesicle showed almost similar results in tension to those of the vas deferens. In the vas deferens or seminal vesicle, an application of hyper-65K+ solution significantly decreased the relative value for the wet weight of the tissue at 120 min, but that of iso-154K+ solution did not affect the wet weight of both the muscles. In the vas deferens, an hyperosmotic addition of sucrose at a concentration of 25 to 100 mM slightly prevented the tension decreased by the iso-154K+ solution and slightly decreased the relative wet weight. In the seminal vesicle, increasing sucrose concentration significantly increased the tension, but decreased the relative wet weight. In both the muscles of vas deferens and seminal vesicle, an addition of pyrvate or oxalacetate (5.5 mM) to the iso-154K+ solution without glucose maintained the muscle tension at a maximal level in the iso-154K+ solution with glucose for 120 min. Further, the tension decrease in both the muscles induced by iso-154K+ solution was also prevented by hyperosmotic application of NaCl. From these results, it is suggested that the tension decrease by high K+, Na+-deficient solution in the vas deferens is mainly caused by an inhibition of glucose utilization by Na+-deficiency in the medium, however, the seminal vesicle is probably due to the cell swelling and partly the inhibition of glucose utilization by it.

Animals↗
PubMed2005

Application of solution calorimetry in pharmaceutical and biopharmaceutical research.

In solution calorimetry the heat of solution (Delta(sol)H) is recorded as a solute (usually a solid) dissolves in an excess of solvent. Such measurements are valuable during all the phases of pharmaceutical formulation and the number of applications of the technique is growing. For instance, solution calorimetry is extremely useful during preformulation for the detection and quantification of polymorphs, degrees of crystallinity and percent amorphous content; knowledge of all of these parameters is essential in order to exert control over the manufacture and subsequent performance of a solid pharmaceutical. Careful experimental design and data interpretation also allows the measurement of the enthalpy of transfer (Delta(trans)H) of a solute between two phases. Because solution calorimetry does not require optically transparent solutions, and can be used to study cloudy or turbid solutions or suspensions directly, measurement of Delta(trans)H affords the opportunity to study the partitioning of drugs into, and across, biological membranes. It also allows the in-situ study of cellular systems. Furthermore, novel experimental methodologies have led to the increasing use of solution calorimetry to study a wider range of phenomena, such as the precipitation of drugs from supersaturated solutions or the formation of liposomes from phospholipid films. It is the purpose of this review to discuss some of these applications, in the context of pharmaceutical formulation and preformulation, and highlight some of the potential future areas where solution calorimetry might find applications.

Algorithms↗
PubMed2004

Development of new organ preservation solutions in Kyoto University.

Although lung transplantation (LTx) has been established as a therapeutic approach for end-stage respiratory failure, several problems remain to be solved. In addition to the serious problem of donor shortage, primary graft failure, which is mostly caused by ischemia-reperfusion injury, a serious problem, and represents one of the most frequent causes of early mortality. The development of a highly reliable organ preservation solution that reduces ischemia-reperfusion injury will improve the functioning of transplanted organs and alleviate the donor shortage. We first evaluated the importance of saccharides and electrolytes in the lung preservation solution. We proved the superiority of trehalose, a non-reducing disaccharide, and the efficiency of the extracellular-type (low potassium) ion composition, and we also developed an extracellular-type trehalose containing Kyoto (ET-Kyoto) solution. Furthermore, several agents for vascular endothelial protection were evaluated, and finally, a more effective solution named "new ET-Kyoto solution" was developed, by adding N-acetylcysteine, dibutyryl adenosine 3', 5'-cyclic monophosphate, and nitroglycerin to the "conventional" ET-Kyoto solution. The new ET-Kyoto solution enabled canine LTx to last up to 30 hours. ET-Kyoto solution has so far been used and produced good results in five clinical LTx throughout Japan and South Korea. Although it was initially developed for lung preservation, its effectiveness in the preservation of various organs/ tissues, such as the trachea, kidney, skin/muscle flap, amputated digits, liver, and pancreas, has also been experimentally and clinically shown. In this paper, clinical and experimental findings with ET-Kyoto solution have been accumulated to further analyze its effect, safety, and chemical stability. We hope to provide ET-Kyoto solution as the standard organ/tissue preserving solution throughout the world.

Animals↗
PubMed2005

Evaluation of CMU-1 preservation solutions using an isolated perfused rat liver model.

AIM: CMU-1 is a new preservation solution with a low potassium concentration as well as low viscosity that is highly effective in reducing preservation injury. The purpose of this experiment is to compare the protective effect of CMU-1 solution with that of UW during cold preservation and normothermic reperfusion. METHODS: Wistar rats were divided into two groups according to different preservation solution: CMU-1 group and UW group. After 6, 12 and 24 h cold storage of rat liver in different preservation solutions, the isolated perfused rat liver model was applied to reperfuse the liver for 120 min normothermically (37 degrees C) with Krebs-Henseleit solution, meanwhile the pH value of the preservation solution was measured. The perfusate was sampled for the evaluation of alanine aminotransferase (ALT) and lactate dehydrogenase (LDH). At the end of the reperfusion, all of the bile product was collected, energy metabolic substrate and histological examination were performed. RESULTS: After preserving for 6 h, pH value of both groups did not change; after 12 h, both decreased but with no significant difference. After 24 h, pH value in UW solution group significantly decreased. The total adenine nucleotides level and AEC in liver tissue decreased with preservation time, but they were higher in CMU-1 group. And the amount of bile product after perfusion for 120 min in CMU-1 group was much more than that in UW group. However, there were no significant differences in ALT and LDH levels between two groups. Histology showed no difference. CONCLUSION: The preservation effect of CMU-1 solution is similar with that of UW solution. However, CMU-1 solution shows some advantages over UW solution in energy metabolism, preventing intracellular acidosis and bile product.

Adenosine↗
PubMedDate not supplied

[The effect of a photo-developing solution on respiratory and cardiac activities in rats when orally administered].

The development of cinema art brought about the increase in the number of laboratories which prepare photosensitive materials. In case of laboratories not complying with rules regarding the preparation and handling of the solutions for processing photos, these solutions can penetrate in the organism trough the skin and be accidentally digested. The goal of the experiment is to study the effects of developing solution for white/black Azomureş photographic paper on respiratory and cardiac activity of the Wistar rat (weight = 180-200 g) through oral administration. Three experimental groups (lots) of animals were formed (8 animals/group). The control group was given 1 ml of distilled water; the first (I) group was given 1 ml of 1/10 diluted photo-processing solution and the second (II) group was given 1 ml of the same solution, but 1/4 diluted. The administration of it was made in a single dose with a gastric drill. The respiratory and cardiac (ECG) frequencies were monitored during a 4 hours period, from the onset of administration. When 1/10 diluted developing solution was administrated a decrease in the respiratory frequency was recorded after one hour, but the effect vanished at the end of the experiment (4 hours). Fifteen minutes after 1/4 diluted solution was administered, a decrease in respiratory frequency per minute was determined, this result also disappeared at the end of 4 hours. However, these differences failed to reach significance (p = 0, 54). The effect of developing solution on cardiac activity shows a decrease of cardiac frequency in both experimental (I, II) groups. However, there is a difference in the effect of the diluted solution on the rats. The 1/10 diluted solution decrease the cardiac frequency over an approximate period of 1 hour and a half, but the 1/4 diluted solution showed a decrease in cardiac frequency up until the end of the ECG reading.

Animals↗
PubMed2000

Biocompatibility of new peritoneal dialysis solutions: what can we hope to achieve?

Despite the bioincompatibility of the "old", standard, high glucose, lactate-buffered peritoneal dialysis (PD) solutions, PD is itself a highly successful dialysis modality with patient survival equivalent to that of hemodialysis (HD) during the initial 3 - 5 years of dialysis therapy. Nevertheless, PD technique survival is often limited by infectious complications and alterations in the structure and function of the peritoneal membrane. These local changes also have a negative impact on patient survival owing to systemic effects such as those often seen in patients with high peritoneal transport rate and loss of ultrafiltration (UF) capacity. Patient mortality remains unacceptably high in both HD and PD patients, with most premature deaths being associated with signs of malnutrition, inflammation, and atherosclerotic cardiovascular disease (MIA syndrome). These systemic signs are likely to be influenced by PD solutions both directly and indirectly (via changes in the peritoneal membrane). New, biocompatible PD solutions may have favorable local effects (viability and function of the peritoneal membrane) and systemic effects (for example, on MIA syndrome). Amino acid-based solution [Nutrineal (N): Baxter Healthcare Corporation, Deerfield, IL, U.S.A.] may improve nutritional status as well as peritoneal membrane viability. Bicarbonate/lactate-buffered solution [Physioneal (P): Baxter Healthcare Corporation] may ameliorate local and systemic effects of low pH, high lactate, and high glucose degradation products. Icodextrin-based solution [Extraneal (E): Baxter Healthcare SA, Castlebar, Ireland] may improve hypertension and cardiovascular problems associated with fluid overload and may extend time on therapy in patients with loss of UF capacity. The positive effects of each of these new, biocompatible solutions have been demonstrated in several studies. It is likely that the combined use of N, P, and E solutions will produce favorable synergies in regard to both local effects (peritoneal viability) and systemic effects (less malnutrition, inflammation, and fluid overload). Solution combination is an exciting area for clinical study in the coming years. Furthermore, dialysis fluid additives such as hyaluronan, which protects and improves the function of the peritoneal membrane, may further improve PD solutions. The new, biocompatible PD solutions represent an entirely new era in the evolution of the PD therapy; they are likely to have markedly positive effects on both PD technique and PD patient survival in coming years.

Amino Acids↗