Phosphotungstic acid immobilized on amino-functionalized TS-1 zeolite as a solid acid catalyst for the synthesis of tributyl citrate

The amino-functionalization of TS-1 zeolite followed by immobilization of phosphotungstic acid(HPW)was presented to prepare a strong solid acid catalyst for the synthesis of bio-based tributyl citrate from the esterification of citric acid and n-butanol.γ-Aminopropyltriethoxysilane(APTES)was first grafted on the TS-1 zeolite via the condensation reactions with surface hydroxyl groups,and subsequently the HPW was immobilized via the reaction between the amino groups and the protons from HPW-forming strong ionic bonding.The Keggin structure of HPW and MFI topology of TS-1 zeolite were well maintained after the modifications.The amino-functionalization generated abundant uniformly distributed active sites on TS-1 for HPW immobilization,which promoted the dispersity,abundance,as well as the stability of the acid sites.The tetrahedrally coordinated framework titanium and non-framework titania behaved as weak Lewis acid sites,and the protons from the immobilized HPW acted as the moderate or strong Brønsted acid sites.An optimized TBC yield of 96.2%(mol)with a conversion of-COOH of 98.1%(mol)was achieved at 150℃for 6 h over the HPW immobilized on amino-functionalized TS-1.The catalyst exhibited good stability after four consecutive reaction runs,where the activity leveled off at still a relatively high level after somewhat deactivation possibly caused by the leaching of a small portion of weakly anchored APTES or HPW.

Usefulness of Newly Devised Clomiphene Citrate Administration Method Compared with the Conventional Method in Ovulation and Pregnancy

Objective: Since not all women wish to conceive a child through aggressive treatment, we investigated the usefulness of modified repeated intracyclic clomiphene citrate (CC) therapy (repeated CC therapy) as a newly devised administration method. Methods: We evaluated the effects of CC administration on menstrual cycle length and retrospectively compared ovulation and pregnancy in 220 women who received CC at our hospital. Patients in the conventional method group received 50 mg per day for five days, starting on the fifth day of menstruation (withdrawal bleeding). Groups with and without menstrual cycle shortening after conventional CC administration were compared. The repeated CC therapy group was also compared with the non-shortened group. Repeated CC therapy was administered for the first five days as in the conventional method, and a second five-day repeat treatment was administered after an interval of five to seven days. Pregnancy rates, including indirect pregnancies, were evaluated by three different methods. Results: Ovulation and pregnancy rates were significantly better in the shortened group than in the non-shortened group (P < 0.001 and P = 0.010, respectively). Even in the non-shortened group, ovulation and pregnancy rates including indirect pregnancies were significantly improved when ovulation was observed with repeated CC therapy (P < 0.001 and P = 0.022, respectively). Conclusions: For patients whose menstrual cycle was not improved or shortened, repeated CC therapy as the newly devised CC administration method is useful as the next step after the conventional CC administration method.

Analysis of the Effect of High-Dose Segmental Citrate Anticoagulation in High Flux Hemodialysis

Objective:To analyze the clinical effect of high-dose citrate in segmental extracorporeal anticoagulation for high-throughput hemodialysis.Methods:The subjects included in this study were admitted to the hospital for maintenance hemodialysis treatment from January 2021 to January 2023.All patients had a high risk of bleeding and received 4%trisodium citrate anticoagulant treatment,administered at a rate of 200 mL/h before and after the dialyzer.The anticoagulant effects achieved by the patients were observed and analyzed.Results:The total number of patients who received high-dose segmented citrate extracorporeal anticoagulation dialysis treatment was 50,with each patient undergoing 100 treatments.During the treatment,2 patients had to end the treatment early due to transmembrane pressure exceeding 30 mmHg and an increase in venous pressure exceeding 250 mmHg;the treatment times for these patients were 20 minutes and 200 minutes,respectively.The remaining patients successfully completed the 4-hour treatment.Blood pH and calcium ion concentration in the venous pot were monitored.It was observed that before dialysis,after 2 hours of dialysis,and at the end of dialysis,the blood pH of the patients remained within a relatively normal range.Although some patient levels changed after dialysis,they remained within the normal range.No adverse reactions(such as numbness of the limbs or convulsions)were observed during the anticoagulant treatment.Conclusion:Administering 4%trisodium citrate at a rate of 200 mL/h before and after the dialyzer achieves a good anticoagulant effect,maintains the patient’s blood gas levels within the normal range at the end of dialysis,and causes no adverse reactions.

^(68)Ga-citrate对软组织感染PET-CT显像基因表达分子机制与验证

目的研究^(68)Ga-citrate对软组织感染正电子发射计算机断层(PET-CT)显像分子机制相关基因Tfrc、Trf、和Ttf对感染应答的基因表达变化,探讨小鼠多药及毒性外排转运子1(multidrug and toxin extrusion1,mMATE1)在小鼠软组织感染的^(68)Ga-citrate PET-CT显像中可能的作用。方法用金黄色葡萄球菌感染小鼠形成脓肿,取不同时间点的脓肿组织,用荧光定量PCR(real-time PCR)鉴定Tfrc、Trf、Ttf基因和mMATE1基因Slc47a1的相对表达量。用^(68)Ga标记柠檬酸(citrate),阻断实验使用PET-CT技术研究mMATE1转运子在小鼠软组织感染^(68)Ga-citrate显像中的相关性。结果real-time PCR显示转铁蛋白TF基因Trf和乳铁蛋白TLF基因Ttf在4 d时间点表达量最高,mMATE1转运子基因Slc47a1的表达类型与转铁蛋白受体TFRC基因Tfrc类似,在1 h左右达到峰值,随后逐渐降低,而Na+偶联的柠檬酸转运子NaCT的基因SLC13A5表达量在所有时间点未有明显变化。Trf、Ttf、Slc47a1和Tfrc基因表达最高值与0 h时间点的表达量相比均有显著差异(57.21±11.62和7.53±1.74,t=35.38;43.03±6.8和6.26±1.32,t=12.05;28.79±2.16和8.21±1.23,t=8.22;1091.36±30.76和290.84±10.62,t=52.08;P<0.01),且Slc47a1基因表达最高值显著高于SLC13A5基因同时间点的基因表达量(28.79±2.16和1.67±0.51,t=79.81,P<0.01)。PET-CT显示^(68)Ga-citrate或^(68)GaCl3尾静脉注射不同处理对小鼠左后腿相应部位^(68)Ga聚集有显著影响(F=13.77,P<0.01),其中炎症小鼠感染部位有明显^(68)Ga聚集(SUVmax=3.87±0.32),而对照未感染部位未见明显^(68)Ga聚集(SUVmax=0.31±0.13),差异有统计学意义(t检验,P<0.01),mMATE1阻断的感染小鼠感染部位对^(68)Ga的摄取明显减少(SUVmax=1.62±1.03),与未阻断感染小鼠比较差异有统计学意义(t检验,P<0.05)。结论从分子水平上证实Tfrc、Trf和Ttf在感染处高表达,多药及毒素外排转运子mMATE1可能参与金黄色葡萄球菌诱导小鼠软组织感染的^(68)Ga-citrate PET-CT显像。

Management of regional citrate anticoagulation for continuous renal replacement therapy:guideline recommendations from Chinese emergency medical doctor consensus

Continuous renal replacement therapy(CRRT)is widely used for treating critically-ill patients in the emergency department in China.Anticoagulant therapy is needed to prevent clotting in the extracorporeal circulation during CRRT.Regional citrate anticoagulation(RCA)has been shown to potentially be safer and more effective,and is now recommended as the preferred anticoagulant method for CRRT.However,there is still a lack of unified standards for RCA management in the world,and there are many problems in using this method in clinical practice.The Emergency Medical Doctor Branch of the Chinese Medical Doctor Association(CMDA)organized a panel of domestic emergency medicine experts and international experts of CRRT to discuss RCA-related issues,including the advantages and disadvantages of RCA in CRRT anticoagulation,the principle of RCA,parameter settings for RCA,monitoring of RCA(mainly metabolic acid-base disorders),and special issues during RCA.Based on the latest available research evidence as well as the paneled experts'clinical experience,considering the generalizability,suitability,and potential resource utilization,while also balancing clinical advantages and disadvantages,a total of 16 guideline recommendations were formed from the experts'consensus.

Preparation of high active Pt/C cathode electrocatalyst for direct methanol fuel cell by citrate-stabilized method

Platinum nanoparticles supported on carbons（Pt/C,60%,mass fraction） electrocatalysts for direct methanol fuel cell（DMFC） were prepared by citrate-stabilized method with different reductants and carbon supports.The catalysts were characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM） and cyclic voltammetry（CV）.It is found that the size of Pt nanoparticles on carbon is controllable by citrate addition and reductant optimization,and the form of carbon support has a great influence on electrocatalytic activity of catalysts.The citrate-stabilized Pt nanoparticles supported on BP2000 carbon,which was reduced by formaldehyde,exhibit the best performance with about 2 nm in diameter and 66.46 m2/g（Pt） in electrocatalytic active surface（EAS） area.Test on single DMFC with 60%（mass fraction） Pt/BP2000 as cathode electrocatalyst showed maximum power density at 78.8 mW/cm2.

Electrochemical reduction process of Co(Ⅱ) in citrate solution

Effects of citrate concentration and pH on the electrochemical reduction process of Co（Ⅱ） were investigated by cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）. The results show that Co（Ⅱ） is reduced into two species which are free Co2＋ and [Co（C6H607）] in the solution composed of 0.05 mol/L CoS04·5H2O, 0.20 mol/L Na2SO4 and 0-0.40 mol/L C6H5O7Na3·2H2O in the pH range of 3-9. The reduction behavior depends on the pH of the solution. Co（H） is mainly reduced into the form of free Co^2＋ at pH 3 and into the form of [Co（C6H6O7）] at the pH range of 4-6 in citrate solution. The [Co（C6H6O7）] is first reduced to an intermediate state and then to Co°. Adsorption of the intermediate state exists on the surface of the electrode. Co（Ⅱ） is difficult to be reduced in the solution with the pH above 7, because the existing Co（Ⅱ）-citrate complex species [Co（C6H5O7）]- and [Co（C6H4O7）]2- are more difficult to be reduced than the hydrogen ion.

几种常用的核染色标记物pH 6.0 Citrate和pH 9.0 Tris/EDTA修复液的比较

目的探讨pH 6.0 Citrate和pH 9.0 Tris/EDTA两种修复液在常用的免疫组化核染色标记物中的染色效果。方法选取本科室常用的3种核/浆标记抗体以及22种核标记抗体分别采用pH 6.0 Citrate和pH 9.0 Tris/EDTA微波热修复进行比较。结果在25种抗体中,其中有11种分别用pH 6.0 Citrate和pH 9.0 Tris/EDTA微波修复染色效果基本一致,在其余14种抗体中,有11种用pH 9.0 Tris/EDTA微波热修复方法进行修复时,阳性信号明显增强;而有3种抗体用pH 6.0 Citrate微波热修复方法进行修复时,阳性信号稍增强。结论对于这25种抗体来说,如果用微波加热的方法进行抗原修复,那么pH 9.0 Tris/EDTA优于PH 6.0 Citrate。

治疗伴有中至严重血小板减少的骨髓纤维化新药——枸橼酸帕西替尼(pacritinib citrate)

骨髓纤维化是一种罕见的骨髓进行性恶性肿瘤,破坏健康血细胞的正常产生,导致骨髓衰竭和严重贫血。帕西替尼(pacritinib)的激酶谱显示其对急性髓系白血病、骨髓增生异常综合征、慢性单核粒细胞白血病和慢性淋巴细胞白血病具有潜在的治疗作用。枸橼酸帕西替尼最初由美国细胞疗法公司开发,2009年1月与美国S*BIO和Onyx制药公司签订开发和商业化协议,成立美国CTI生物制药公司,重点开发枸橼酸帕西替尼,用于治疗骨髓增生和移植物抗宿主病等疾病。2012年4月,成立CTI生物制药公司,与美国S*BIO和Onyx制药公司重新签订协议,CTI将收回帕西替尼全球开发权利。2020年10月13日CTI生物制药公司向美国食品药品管理局(FDA)提交滚动新药申请,寻求批准枸橼酸帕西替尼用于治疗严重血小板减少症(血小板计数<50×10^(9)·L^(-1))的骨髓纤维化。2022年2月28日,美国FDA批准枸橼酸帕西替尼胶囊上市,商品名Vonjo®,用于治疗成人血小板计数<50×10^(9)·L^(-1)的中高危原发性或继发性(真性红细胞增多症后或原发性血小板增多症)的骨髓纤维化。该文对枸橼酸帕西替尼胶囊的非临床和临床药理毒理学、临床研究、不良反应、适应证、剂量与用法、用药注意事项及知识产权状态和国内外研究进展等进行介绍。

Removal of citrate and hypophosphite binary components using Fenton,photo-Fenton and electro-Fenton processes

Both citrate and hypophosphite in aqueous solution were degraded by advanced oxidation processes （Fe^2＋/H2O2, UV/Fe^2＋/H2O2, and electrolysis/Fe^2＋/H2O2） in this study. Comparison of these techniques in oxidation efficiency was undertaken. It was found that Fenton process could not completely degrade citrate in the presence of hypophosphite since it caused a series inhibition. Therefore, UV light （photo-Fenton） or electron current （electro-Fenton） was applied to improve the degradation efficiency of the Fenton process. Results showed that both photo-Fenton and electro-Fenton processes could overcome the inhibition of hypophosphite, especially the electro-Fenton.

Can mosapride citrate reduce the volume of lavage solution for colonoscopy preparation?

AIM:To evaluate the possibility of reducing the volume of polyethylene glycol(PEG)-electrolyte solution using adjunctive mosapride citrate for colonoscopy preparation. METHODS:This was a single-center,prospective, randomized,investigator-blinded,non-inferiority study involving 252 patients of both sexes,aged from 20 to 80 years,scheduled for screening or diagnostic colonoscopy in our department.A total of 126 patients was randomized to receive 1.5 L PEG-electrolyte solution plus 15 mg of mosapride(1.5 L group),and 126 received 2 L PEG-electrolyte solution plus 15 mg of mosapride(2 L group).Patients completed a questionnaire on the acceptability and tolerability of the bowel preparation process.The efficacy of bowel preparation was assessed using a 5-point scale based on the Aronchick scale.The primary end point was adequate bowel preparation rates(score of excellent/good/fair) vs(poor/inadequate).Acceptability and tolerability,as well as disease detection,were secondary end points. RESULTS:A total of 244 patients was included in the analysis.There were no significant differences between the 2 L and 1.5 L groups in age,sex,body mass index, number of previous colonoscopies,and the preparation method used previously.The adequate bowel preparation rates were 88.5%in the 2 L group and 82.8%in the 1.5 L group[95%lower confidence limit(LCL)for the difference=-14.5%,non-inferiority P=0.019]in the right colon.In the left colon,the adequate bowel preparation rates were 89.3%in the 2 L group and 81.1%in the 1.5 L group(95%LCL=-17.0%,non-inferiority P=0.066).Compliance,defined as complete (100%)intake of the PEG solution,was significantly higher in the 1.5 L group than in the 2 L group(96.8% vs 85.7%,P=0.002).The proportion of abdominal distension(none/mild/moderate/severe)was significantly lower in the 1.5 L group than in the 2 L group (36/65/22/3 vs 58/48/18/2,P=0.040).Within the subgroup who had undergone colonoscopy previously, a significantly higher number of patients in the 1.5 L group than in the 2 L group felt that the current preparation was easier than the previous one(54.1%vs 28.0%,P=0.001).The disease detection rate was not significantly different between the two groups. CONCLUSION:Although the 1.5 L group had better acceptability and tolerability,15 mg of mosapride may be insufficient to compensate for a 0.5-L reduction of PEG solution.

Competitive and cooperative adsorption of arsenate and citrate on goethite

The fate of arsenic in natural environments is influenced by adsorption onto metal （hydr）oxides. The extent of arsenic adsorption is strongly affected by coexisting dissolved natural organic acids. Recently, some studies reported that there existed competitive adsorption between arsenate and citrate on goethite. Humic acid is known to interact strongly with arsenate by forming complexes in aqueous solution, hence it is necessary to undertake a comprehensive study of the adsorption of arsenate/citrate onto goethite in the presence of one another. The results showed that at the arsenate concentrations used in this study （0.006-0.27 mmol/L）, citrate decreased arsenate adsorption at acidic pH but no effect was observed at alkaline pH. In comparison, citrate adsorption was inhibited at acidic pH, but enhanced at alkaline pH by arsenate. This was probably due to the formation of complex between arsenate and citrate like the case of arsenate with humic acid. These results implied that the mechanism of the adsorption of arsenate and citrate onto goethite in the presence of one another involved not only competition for binding sites, but the cooperation between the two species at the watergoethite interface as well.

Effect of calcium citrate on bone integration in a rabbit femur defect model

Objective:To explore effect of calcium citrate on bone integration in a rabbit femur defect model, and to compare the bone formation with different sizes by radiological and histological study. Methods:Twenty-four male Japanese white rabbits were randomly divided into three groups (Group A.B.C)in this study.Under anesthesia,defects of four sizes(1.2,1.5,2.0 and 2.5 mm) were created in each of the rabbits.Commercially pure calcium citrate powder was placed inside the medullary compartment of the femur(Experimental),while in the contralateral femur(Control) nothing was implanted.The defects were analyzed using radiography and histological analysis by using Imagepro-Plus 6.0 software after animal was sacrificed at 4th(Group A),6th(Group B) and 8th(Group C) weeks postoperatively.Four samples were analyzed for each size of defect and each healing period.Results:The histological and the radiologic evaluation were performed after sacrification of all rabbits on postoperative 4th and 6th weeks,It showed significant difference between the experimental group and the control group when these defects were less than or equal to 2.0 mm.No statistical difference was observed when these defects were larger than 2.0 mm at all healing periods except at the 4th week.Conclusions:Calcium citrate affects the early periods of hone defects healing mechanism in Japanese white rabbits positively,especially when the defect is not too large,We suggest further studies on calcium citrate to determine the effects of various dosages,administration ways and the experimental time on the bone defects.

Assessment of heme oxygenase-1 （HO-1） activity in the cavernous tissues of sildenafil citrate-treated rats

Aim： To assess heine oxygenase-1 （HO-1） activity in the cavemous tissue of sildenafil citrate-treated rats. Methods： One hundred and ninety-two Sprague-Dawley male rats, divided into four equal groups, were investigated. Group 1, the control group, received regular animal chow; group 2 received sildenafil citrate by intragastric tube; group 3 received sildenafil and HO inhibitor （zinc protoporphyrin, ZnPP）; and group 4 received sildenafil and nitric oxide synthase （NOS） inhibitor L-nitroarginine methyl ester （L-NAME）. Twelve rats from each group were killed after 0.5 h, 1 h, 2 h and 3 h of drug administration. Then HO-1 activity, cGMP levels and NOS enzymatic activity in the cavernous tissues were estimated. Results： In cavemous tissue, HO-1 activity, NOS enzymatic activity and cGMP concentration increased significantly in sildenafil-treated rats compared to other groups throughout the experiment. Rats receiving either HO or NOS inhibitors showed a significant decrease in these parameters. HO- 1 cavemous tissue activity and NOS enzymatic activity demonstrated a positive significant correlation with cGMP levels （r = 0.646, r = 0.612 respectively; P 〈 0.001）. Conclusion： The actions of PDE5 inhibitor sildenafil citrate in the cavernous tissue are partly mediated through the interdependent relationship between both HO-1 and NOS activities.

Synthesis, Crystal Structure and Characterization of a New Zinc Citrate Complex

A new Zn-citrate coordination complex {K[Zn（C6H5O7）（H2O）]}n（1） was synthesi- zed via hydrothermal reaction. In the crystal structure of complex 1, each citrate serves as thequadricdentate ligand coordinating to three Zn（II） ions, forming a zigzag chain, and such chains are further connected into a 3D network by the K＋ linkers. Crystal data for complex 1： triclinic, space group Pī, α = 7.3487（9）, b = 7.5397（6）, c = 9.6772（8） A, α = 76.894（8）, β = 68.260（10）, γ = 65.155（10）°, V = 450.34（7） ？3 and Z = 2. Other characterizations by elemental analysis, IR, TG and fluorescence were also described.

Clomiphene Citrate Induces ROS-Mediated Apoptosis in Mammalian Oocytes

The clomiphene citrate (CC), a nonsteroidal triphenylethylene compound, is a first line of medicine used for the induction of ovulation in anovulatory women worldwide. In spite of high ovulation induction with the use of CC, the pregnancy rate is much lower. Such a discrepancy could be due to the peripheral anti-estrogenic effect of CC, particularly at the level of ovary, endometrium and cervical mucus. CC induces ovulation by binding to the estrogen receptors and generates hypoestrogrnic state in hypothalamus leading to release of pituitary gonadotropins. CC may have a direct effect at the level of ovary but the molecular mechanism remains unclear. Animal studies suggest that the CC induces apoptosis in granulosa cells and results hypoestrogenic state in the ovary. Reduced estradiol 17β level in the ovary affects development and maturation of oocyte leading to oocyte apoptosis. Further, CC increases hydrogen peroxide (H2O2) level and thereby bax protein expression and DNA fragmentation in cumulus-granulosa cells as well as in oocytes. The exogenous supplementation of either estradiol 17β or melatonin reduces H2O2 level in ovary, delays meiotic cell cycle progression in oocyte and protects oocyte apoptosis. Hence, supplementation of estradiol 17β or melatonin along with CC could be beneficial to protect granulosa cell as well as oocyte apoptosis and inhibit deterioration of oocyte quality. Thus, maintenance of oocyte quality may overcome the adverse effect caused due to CC treatment during infertility management.

Efficacy of mosapride citrate with polyethylene glycol solution for colonoscopy preparation

AIM:To evaluate the efficacy and safety of adjunctive mosapride citrate for bowel preparation before colonoscopy. METHODS:We conducted a randomized,double-blind, placebo-controlled study with mosapride in addition to polyethylene glycol(PEG)-electrolyte solution.Of 250 patients undergoing colonoscopy,124 were randomized to receive 2 L PEG plus 15 mg of mosapride citrate (mosapride group),and 126 received 2 L PEG plus placebo(placebo group).Patients completed a questionnaire reporting the acceptability and tolerability of the bowel preparation process.The efficacy of bowel preparation was assessed by colonoscopists using a 5-point scale based on Aronchick's criteria.The primary end point was optimal bowel preparation rates(scores of excellent/good/fair vs poor/inadequate). RESULTS:A total of 249 patients were included in the analysis.In the mosapride group,optimal bowel preparation rates were significantly higher in the left colon compared with the placebo group(78.2%vs 65.6%,P<0.05),but not in the right colon(76.5%vs 66.4%,P=0.08).After excluding patients with severe constipation,there was a significant difference in bowel preparation in both the left and right colon(82.4%vs 66.7%,80.8%vs 67.5%,P<0.05,P<0.01).The incidence of adverse events was similar in both groups. Among the subgroup who had previous colonoscopy experience,a significantly higher number of patients in the mosapride group felt that the current preparation was easier compared with patients in the placebo group(34/72 patients vs 24/74 patients,P<0.05). CONCLUSION:Mosapride citrate may be an effective and safe adjunct to PEG-electrolyte solution that leads to improved quality of bowel preparation,especially in patients without severe constipation.

Treatment preferences in men with erectile dysfunction： an open label study in Korean men switching from sildenafil citrate to tadalafil

To evaluate patient preferences for sildenafil citrate or tadalafil （PDE-5 inhibitors available for the treatment of erectile dysfunction [ED]） and assess potential reasons for these preferences. Methods： This open-label study was conducted on Korean men taking sildenafil, at least 6 weeks prior to study entry, for ED. Following screening, patients continued sildenafil treatment for 4 weeks, then after a 1-week washout period, switched to tadalafil for 8 weeks. Patients then continued with their treatment of choice during an extension phase. Psychosocial factors （time concern, spontaneity, sexual self-confidence） were evaluated using Psychological and Interpersonal Relation- ship Scales （PAIRS）, while timing of dose to sexual attempt patterns were assessed from patient diaries. Results： The present study enrolled 160 Korean men （mean age 55 years） with prior median sildenafil use of 585 days. During the extension phase, 73.7% of patients elected to take tadalafil, whereas 26.3% chose sildenafil （P 〈 0.001）. After switching from sildenafil to tadalafil, mean PAIRS time concern scores decreased from 2.54 to 2.42 （P = 0.002）, with no statistically significant differences observed between the sildenafil and tadalafil assessment phases in sexual spontaneity and self-confidence scores. Sexual attempts made 〉 4 h to 〈 36 h post-dose occurred in 4.5% of patients during the sildenafil assessment phase compared with 17.5% during the tadalafil assessment phase. Conclusion： After experiencing both sildenafil and tadalafil, the majority of patients exhibited a preference for tadalafil. This preference might be influenced by psychosocial factors, such as decreased time concerns, and a broader window of opportunity available for sexual activity.

Study of <i>in Vitro</i>Interaction of Sildenafil Citrate with Bovine Serum Albumin by Fluorescence Spectroscopy

In vitro interaction of sildenafil citrate (SC) with bovine serum albumin (BSA) was investigated at two excitation wavelengths of BSA (280 nm and 293 nm) at two different temperatures (298 K and 308 K) by fluorescence emission spectroscopy. The study showed that quenching of BSA fluores-cence by sildenafil citrate was the result of formation BSA-SC complex with probable involvement of both tryptophan and tyrosine residues of BSA. Fluorescence quenching constant was determined from Stern-Volmer equation, and both static quenching and dynamic quenching were showed for BSA by SC at the conditions. Van’t Hoff equation was used to measure the thermodynamic parameters ΔG, ΔH, and ΔS at the temperatures which indicated that the hydrogen bond and the hydrophobic forces played major roles for BSA-SC complexation. The binding number (n) was found to be ≈1 indicating that one mole BSA bound with one mole SC. The binding affinity of SC to BSA was calculated at different temperatures. The binding constant was decreased with increasing temperatures indicating that stability of BSA-SC complex decreased with increasing temperatures.