- Ramona Khanum added an answer:I have been trying to develop a HPLC method for Meropenem trihydrate but failed in many attempts. Are there any suggestions?I have tried the following mobile phase solvents and ratios of them.
I am using 1ml/min FR and 298nm WL. Either I do not get the peak, it is too near the solvent peak, peaks not reproducible or they do not increase proportionally to increasing concentration:-
1. Methanol, Acetonitrile, Both combined at 50:50 ratio.
2. KH2PO4, K2HPO4, Orthophosphoric acid solution, Ammonium acetate buffer (at different molarities and pH), water.
Note: UV spec WL detection of the drug was 200, but this would be not appropriate as an HPLC WL choice.Hi Anuj. Thanks a lot for the suggestion but I have solved the problem (gotten the peaks) as I mentioned just above your reply. Thanks again and have a nice day.Following
- Abdul Mannan Baig added an answer:How specific is trifluoperazine on phospholipase A2 since it possesses many other pharmacological properties?I am interested in trifluoperazine,TFP.This drug has vide range of actions on dopaminergic and adrenergic receptors. The prototype of the family has 12 different actions, so the specificity on Phospholipase A2 is not so specific, as many of its action may actually antagonize this enzyme activation as well. hope this helps.Following
- Saeed Ahmad Khan added an answer:Quantification of lysozyme in solution containig gelatin.I want to quantify lysozyme in my sample (containing gelatin). I cannot use BCA assay because my sample contains gelatin as well. Is there any other way to quantify it with it being interfered by gelatin in the sample?Thanks alot.Following
- Majeed Ullah added an answer:How can I analyse succinic acid concentration in solution as it is UV non active?I have used succinic acid with my drug to form its cocrystal. I can analyze my drug with HPLC in sample but when it comes to SA it gives no absorption, if anyone has past experience with SA, Please share.Alan Thanks alot helpful, I have already requested for LC-MS facility for detecting succinic acid and your references are sound, so we can now easily detect succinic acid.Following
- Venkataranganna Marikunte added an answer:Is there any form of Pirfenidone for parenteral use?I couldn't find any label of Pirfenidone for parenteral use. If there is no parenteral form of it please somebody give me information how to use the solid form (tablet) for intraperitoneal use?Pure powder is available from Sigma, which can be used by ip route or you can contact manufacturer for pure sample.
Tablets can be powdered and used orally in animal studies. Do you any specific reason to use by ip?Following
- Wayne Briner asked a question:Does anyone have a manual or a link for the old Szent-Gyorgi & Blum Continuous flow system? Anyone have a manual for this?It seems like it might be useful, but not sure what else I would need.Following
- Cheng Zhou added an answer:Do I need a permission to copy any figure from a research article for my review article?I am writing a review article on some target, and in one of the research papers one figure is reported. I want to add this figure to my review article. Can i do this without permission to the editor or I need permission. How to do it. Please answer.After my own research, I recommend the following two options:
1. The best way to use figures and tables in a published source is to revise and combine them with something of your own. Because data is not subject to copyright. In this way, you only need to cite the source properly without asking for permission.
2. If you do need to ask for permission , check for the source copyright owner if they are included in Rightslink. If so, it is usually free to use 2-5 figures/tables and the application processes are all online and can be done within 2-5 mins.
Hope it helps.
- Edward Russak added an answer:Is potassium sodium hydrogen citrate a single compound?We are studying potassium sodium hydrogen citrate granules, its brand name is Uralyt, but we don't know whether it contains three compounds of potassium citrate, sodium citrate, citrate acid, or one compound of potassium sodium hydrogen citrate.CAS registry number (Chemical Abstracts Service)
- Silke Brüderlein added an answer:Is any biological vector associated with drug delivery in cancer?In cancer, the most awful situation after getting a chemotherapeutic agent, is its delivery. I heard about various vectors employed in their delivery. But is there any clinical or associated reports regarding to this concern?Have you ever thought about WGA (wheat germ agglutinin, that's a lectin present in grains of grass)? That's a small molecule that binds very effectively to acetylglucosamine and N-acetylneuramine acid. It is used to "transport" different substances into the cells . It also passes the bood-brain barrier.
Toxicol Appl Pharmacol. 2011 Feb 15;251(1):79-84.
Vaccine. 2011 Oct 13;29(44):7631-7.
J Pharm Sci. 2013 Apr;102(4):1281-9.
Int J Pharm. 2010 Nov 15;400(1-2):201-10.
Pharm Res. 2012 Feb;29(2):546-58.Following
- Mohd Shakrie Palan Abdullah added an answer:What is the best method to detect amino acids?The source is a new gelatin source. Methods given are by HPLC, amino acid analyzer and LCMS; are there any new methods?Thanks Fakhrul khan.Following
- Gandhidas Sonajirao Lavekar added an answer:Hypolipaedemic - Cholesterol lowering ploy-herbal(only two ingredients) drug can be developed on the basis of traditional plants which are proved hav...There are many herbs having cholesterol lowering action we can identify among them.
Involvement of research laboratory, pharmaceutical institute or company is essential.First of all extremely sorry for delayed answer as I am busy in many aspects of health and medico-bio research. Yes, in all herbs active-bio chemicals are present, without which no action will be observed; the group of scientist / a researcher has to identify a potential phyto-chemical to be labeled as Bio-marker. A prominent phyto-chemical may not have action but it presence may be considered as chemical marker for genuineness-identity of the plant species. The identification of any chemical marker in solvents is depend on the solvency in that particular solvent. Botanical markers are only for deciding genuineness of the plant species, yes many times the Botanical marker and Bio-markers remain same. Exclusive Botanical marker is not considered for dose selection. No all herbs marker compounds are available in any where, so no question of Ayurvedic pharmacopoeia in this regard. As per my knowledge goes about 400 marker compounds are available, the number is very less compared to vast vegetable kingdom. 6-8 gms powder dose is in general of any Churna=powder, the dose of capsules depends on type of extract, the part of the plant from which extract is derived, the yield of the extract, age of the patient, type of patients Prakruti=Bio-identity (Physico-Psychos) etc. If any query may contact meFollowing
- Zhi Rong Qian added an answer:Which potent anticancer chemo-drugs failed in the clinics due to limitations in drug targeting and drug delivery?We know that many of the chemotherapeutic drugs (especially anti-cancer drugs) fail in clinics, not because of their lack of potency, but because of the delivery and targeting issues to the organ of interest. As a young researcher who wishes to build a career in the field of nano-enabled drug delivery, I'm very much interested to know the pulse of clinicians and pharma people and wish to know their particular needs.Pancreatic ductal adenocarcinoma.Following
- Pawel P. Sobecki added an answer:Does anybody know a method that can show the conformation of my co-polymer (random, block, etc...)?PMMA-EMA co-polymer conformation after ATRP co-polymerizationFollowing
- Tibebu Mamuye asked a question:What is the best method for the extraction of ceramides from plants?Ceramide is an important component of the sphingolipids in many eukaryotic species with the important exception of mammals. The lipid components of the ceramide phosphatidylinositol of the few plant species to have been studied are mainly saturated, with primarily phytosphingosine as the long-chain base and tetracosanoic acid (24:0) as the fatty acid component. Ceramide phosphatidylinositol per se tends to contain a wider range of lipid constituents.Following
- Thomas Schubert added an answer:Does anyone know a simple technique for studying small molecule-DNA interactions, especially binding type kinetics?.Microcale thermophoresis is a fantastic technology to study small compound-DNA interactions. It is fast, flexible and consumes low material.
Read about it here http://2bind.de/moleculareinteraction/techniques/Following
- Joe Olechno added an answer:Does anybody know how I can get or where I can find the Aspartate Transcarbamoylase inhibitor N-(Phosphonacetyl)-l-Aspartate PALA?PALA is a potent competitive inhibitor of Aspartate Transcarbamoylase; it binds to and blocks the active sites of the protein, due to it is a Bisubstrate Analog. I have read some papers, where it is provided by the Developmental Therapeutics Program of the National Cancer Institute (USA). But I don't know how to proceed in order to request any chemical reagent from that organization.If you want to contact the DTP at the NCI you can do so at email@example.com.Following
- Mayur Raval added an answer:Can anyone help with a guideline or validation of measurement of spray pattern and plume geometry of OINDP products?For measurement of Spray pattern and plume geometry of OINDP different Instruments like Sprayview, ADSA, Oxford laser are available. But if we compare the data or results every instrument having the different results for Same bottle or canister. Unlikely in content determination of same bottle or canister in HPLC of different make. Some automated actuators also have the same problem. Can any one help in this regard, how to solve the data variability issue if I am using two different make instrument. One for development purpose and another for in vitro studies. My development data and in vitro datas are different.Dear Biswajit, i agree with you, when we are doing same analysis with diffrent make of instrument (whether its HPLC or sprayview) it tends to differ from other make because of principle and applicability difference in make to make. Best way to eliminate the variation and establish authentisity is to keep one control or reference standard. When we are analysing same sample in diffrent make of HPLC we need to keep one standard along with sample as a reference and control. Similarly we can analyse a reference sample or calibration standard in sprayview also. I hope it may give you authentic results.Following
- Omprakash Tanwar added an answer:Need Guidance regarding DPP-IV assay.I purchased a DPP-IV kit from CuaBio. Actually, I wanted to screen my synthetic compounds against DPP-IV enzyme but unfortunately I have purchased a kit with human DPP-IV antibody coated Elisa kit. What can I do to screen my compounds with this kit? Please help me regarding thisDear Sir,
thank you very much for your kind reply
Can I use its enzyme for my assay.Following
- G. Grimble added an answer:What do you think of dimethylglycine?What is our take on dimethylglycine?The issue here is whether the diet is adequate with regards to labile methyl groups from compounds such as betaine, choline or dimethylglycine (DMG) or even lecithins as a class. The fact that DMG can be synthesised in the body does not mean that it does not require supplementation (Michael's point) nor does it mean that this is the only way to meet methyl requirements (Richard's point) which might be increased in an inflammatory condition which involves increased de novo purine synthesis (e.g. the immunisation model of Graber et al 1981 cited above).
There is a very thought-provoking paper from John Brosnan and others, on the general issue of whether dietary methyl intake is sufficient
S. H. Mudd, J. T. Brosnan, M. E. Brosnan, R. L. Jacobs, S. P. Stabler, R. H. Allen, D. E. Vance, and C. Wagner. Methyl balance and transmethylation fluxes in humans. Am.J.Clin.Nutr. 85 (1):19-25, 2007.
J. T. Brosnan, R. da Silva, and M. E. Brosnan. Amino acids and the regulation of methyl balance in humans. Curr.Opin.Clin.Nutr.Metab.Care 10 (1):52-57, 2007.
L. M. Stead, J. T. Brosnan, M. E. Brosnan, D. E. Vance, and R. L. Jacobs. Is it time to reevaluate methyl balance in humans? Am.J.Clin.Nutr. 83 (1):5-10, 2006.
If folic acid status defines the efficiency of methylation then methyl availability defines its capacity.
So in answer to Pietro's question:-
1. I think that DMG is important, just as pyruvate is
2. Supplementation with DMG is a waste of money when the right foods will do the same job, IF SOMEONE HAS "INADEQUATE METHYL STATUS". I don't know how you would test this on a practical level.
3. Methyl status is very important and I've written about this elsewhere.
G. K. Grimble. Sulphur amino acids and immune function. In: Diet, Immunity and Inflammation, edited by P. C. Calder and P. Yaqoob, Cambridge:Woodhead Publishing, 2013, p. 544-569.Following
- Dhawal Raghuvanshi added an answer:What are the preferable iv vehicle system for in vivo study?Synthesized compounds need to dissolve in suitable system before injection and some solvents have limitations, like DMSO can not be used more than 20 %.Following
- Gamal Eldein Fathi added an answer:What is the different between IC50, GI50, and ED50?Can anybody differentiate these? Its looks very similar but with different way of presentation.Thanks a lot for all friends and Profs. who give me the complete answer with support be in contactFollowing
- Gianfranco Baronzio added an answer:What are the barrier mechanisms to drug distribution and how are they altered in disease state?.
The barriers to drug penetration may be multiple, should be specified via the penetration of the drug and the tissue to reach. Some aspects may be related to physicochemical factors of the drug other barriers are specific to individual tissues, organs or tissues.Following
- Fleming Martínez added an answer:Which is a better mathematical model to estimate the solubility of a drug?The solubility of a drug is the most important data in its formulation. However, mathematical models are poor predictives, so I wonder which model you think is the best.This paper by Prof. Jouyban could help you if you are interested in cosolvent mixtures: http://www.ualberta.ca/~csps/JPPS10_3/MS_1168/MS_1168.htmlFollowing
- Sarita Shah added an answer:How to determine the % cumulative drug release from PLGA microparticles?I am determining the in vitro drug release profile from micro-particles, where I have 10 mg microparticles suspended in 5 ml release medium and at each time points I withdraw 1 ml of supernatant (replacing with 1 ml of fresh release medium) and analyze it with HPLC. However, I am getting a bit confused regarding % cumulative release calculations. Do I simply add up the percentage release values at each time points? My confusion is that since I withdraw just 1 ml (out of 5 ml) for analysis, do I need to account for total volume and how do I account for dilution when I replace with 1 ml fresh media? Any help will be appreciated. Thank you.You could also remove all of the medium and replace it with fresh. You would also create a better sink for release that way. Centrifuge the PLGA microparticles down and carefully aspirate with a pipetter.Following
- Hossein Babaei added an answer:Which kind of compounds can show activity via oral administration ?Is there any specific criteria for compounds to check it is suitable for orally active??Agree with SIr. Ashraf Abadi, however, the point raised by Prof. Fatih Uckun is very important as well.Following
- Cristian D. Ene added an answer:What is the best method to remove traces of chromium salts (presumably Cr3+) from organic compounds containing -COOH group?Which is a simple method to determine ppm quantities of Cr3+ after purification?Following
- Daniel Ricardo Delgado added an answer:Can anyone tell me how to perform equilibrium solubility studies step by step practically?Is there any video, presentation or article where a detailed step by step procedure is given for performing solubility studies?SHAKE-FLASK METHOD
The shake-fl ask method proposed by Higuchi and Connors is the most reliable and widely used solubility measurement method. This method determines thermodynamic solubility and could be carried out in fi ve steps.
1. Sample preparation: An excess amount of drug is added to the solubility medium. The added amount should be enough to make a saturated solution in equilibrium with the solid phase. In the case of acidic or basic drugs dissolved in an unbuffered solubility medium, further addition of the solid could change the pH of the solution and consequently the solubility of the drug.
2.Equilibration: Depending on the dissolution rate and the type of agitation used, the equilibration time between the dissolved drug and the excess solid could be varied. Equilibration is often achieved within 36 h. To ensure the equilibration condition, the dissolution profi le of the drug should be investigated. The shortest time needed for reaching the plateau of drug concentration against time could be considered a suitable equilibration time. Any signifi cant variation of the dissolution profi le after reaching the equilibration should be inspected, since there are a number of possibilities including degradation of the drug as well as its polymorphic transformation. Both of these affect the solubility values of a drug dissolved in the dissolution media. Vortexing or sonicating the sample prior to equilibration could reduce the equilibration time. To overcome the poor wettability of low soluble drugs, one may use small glass microspheres or sonication.
3. Separation of phases: Two common methods used for phase separations of saturated solutions are fi ltration and centrifugation. Filtration is the easiest method; however, the possible sorption of the solute on the fi lter should
be considered as a source of error in solubility determinations, especially for very low soluble drugs. Prerinsing the fi lter with the saturated solution could reduce the sorption of the solute on the fi lter by saturating the adsorption sites. Centrifugation or ultracentrifugation is preferred in some cases, and the higher viscosity of the saturated solutions, i.e., in mixed solvents, should be considered as a limitation. A combination of fi ltration and centrifugation could also be used
4. Analysis of saturated solution and the excess solid:UV spectrophotometric analysis is the most common and the easiest analytical method in solubility determination experiments. The next is the high-performance liquid chromatography (HPLC) methods in both the isocratic and gradient elution modes. The HPLC analysis could also detect the possible impurities or degradation products if a highly selective method was used. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) of the residual solid separated from the saturated solution confirm the possible solid-phase transformations during equilibration.
5. Data analysis: The collected data could be compared with the previously reported data to ensure the accuracy of the experimental procedure employed. Any mistake in the dilution step, any miscalculations, or using uncalibrated instruments, such as uncalibrated balances, temperature variations, and some other factors, could result in different solubility values for a given drug dissolved in a solvent at a fixed temperature.Following
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