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Hopefully this will prove to the doubters that there are genetic ...

Posted at 1:36 PM on Apr 25, 2008 by concernedcitizen, #29921
Hopefully this will prove to the doubters that there are genetic reasons for the variation of efficacy and adverse side effective when taking Montelukast. I have several areas of concern (concerned citizen is concerned). One of the main areas is the reliability of Montelukast due to differences in genetics among populations. The cysLT1 (Singulair) receptor is a GENE. As I said before, it would be possible to predict those patients for which Montelukast would and would not be effective and those patients whose gene expression profile would cause them to have unwanted side effectives. I have been looking for a way to give reasonable proof of that which could be used to convince your doctors that Montelukast is not for everybody. I happened to locate a researcher who had invented and patented methods for predicting drug sensitivity and efficacy in inflammatory disease. I have quoted below from his patent application. He intended to provide a method for determining efficacy and drug sensitivity for pharmaceuticals which include leukotriene antagonists - Montelukast. Quoted from: Methods for predicting drug sensitivity in patients afflicted with an inflammatory disease US Patent Issued on December 12, 2006 Methods are disclosed for predicting the efficacy of a drug for treating an inflammatory disease in a human patient, including: obtaining a sample of cells from the patient; obtaining a gene expression profile of the sample in the absence and presence of in vitro modulation of the cells with specific cytokines and/or mediators; and comparing the gene expression profile of the sample with a reference gene expression profile, wherein similarities between the sample expression profile and the reference expression profile predicts the efficacy of the drug for treating the inflammatory disease in the patient. ----------------------------------------------------------- The field of pharmacogenomics measures differences in the effect of medications that are caused by genetic variations. Such differences are manifested by differences in the therapeutic effects or adverse events of drugs. For most drugs, the genetic variations that potentially characterize drug-responsive patients from non-responders remain unknown. --------------------------------------------------------- In another embodiment, the invention is directed to a method for predicting the efficacy in a human asthma patient of leukotriene antagonists including, but not limited to, montelukast (a.k.a., SINGULAIR™; Merck, Whitehouse Station, N.J.), zafirlukast (a.k.a., ACCOLATE™, AstraZeneca, Wilmington, Del.), and zileuton (a.k.a., ZYFLO™; Abbott Laboratories, Chicago, Ill.), comprising: obtaining a sample of cells from the patient; obtaining a gene expression profile from the sample in the absence and presence of in vitro modulation of the cells with specific mediators; and comparing the gene expression profile of the sample with a reference gene expression profile, wherein similarity in expression profiles between the sample and reference profiles predicts the efficacy in the human asthmatic patient of leukotriene antagonists. Many of the cells involved in causing airway inflammation are known to produce signaling molecules within the body called "leukotrienes." Leukotrienes are responsible for causing the contraction of the airway smooth muscle, increasing leakage of fluid from blood vessels in the lung, and further promoting inflammation by attracting other inflammatory cells into the airways. Oral anti-leukotriene medications have been introduced to fight the inflammatory response typical of allergic disease. These drugs are used in the treatment of chronic asthma. Recent data demonstrates that prescribed anti-leukotriene medications can be beneficial for many patients with asthma, however, a significant number of patients do not respond to anti-leukotriene drugs. -------------------------------------------------- The genes selected are those that have been determined to be differentially expressed in either a disease, drug-responsiveness, or drug-sensitive cell relative to a normal cell and confer power to predict the response to the drug. By comparing tissue samples from patients with these reference expression profiles, the patient's susceptibility to a particular disease, drug-responsiveness, or drug-resistance can be determined. http://www.patentstorm.us/patents/7148008-description.html The inventor's website: Hakon Hakonarson M.D. The Children's Hospital of Philadelphia http://stokes.chop.edu/research/profiles/?ID=251
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Reply about 1 year ago on Apr 25, 2008 by concernedcitizen, #7622

The cysLT1 receptor was known to be a gene in 1999 and believed to be on the x chromosome.

All: 1 Review: 0 Click to change filter selection through MyNCBI.

1: Nature. 1999 Jun 24;399(6738):789-93. Links
Characterization of the human cysteinyl leukotriene CysLT1 receptor.Lynch KR, O'Neill GP, Liu Q, Im DS, Sawyer N, Metters KM, Coulombe N, Abramovitz M, Figueroa DJ, Zeng Z, Connolly BM, Bai C, Austin CP, Chateauneuf A, Stocco R, Greig GM, Kargman S, Hooks SB, Hosfield E, Williams DL Jr, Ford-Hutchinson AW, Caskey CT, Evans JF.
Department of Pharmacology, University of Virginia Health Sciences Center, Charlottesville 22908, USA.

The cysteinyl leukotrienes-leukotriene C4(LTC4), leukotriene D4(LTD4) and leukotriene E4(LTE4)-are important mediators of human bronchial asthma. Pharmacological studies have determined that cysteinyl leukotrienes activate at least two receptors, designated CysLT1 and CysLT2. The CysLT1-selective antagonists, such as montelukast (Singulair), zafirlukast (Accolate) and pranlukast (Onon), are important in the treatment of asthma. Previous biochemical characterization of CysLT1 antagonists and the CysLT1 receptor has been in membrane preparations from tissues enriched for this receptor. Here we report the molecular and pharmacological characterization of the cloned human CysLT1 receptor. We describe the functional activation (calcium mobilization) of this receptor by LTD4 and LTC4, and competition for radiolabelled LTD4 binding to this receptor by the cysteinyl leukotrienes and three structurally distinct classes of CysLT1-receptor antagonists. We detected CysLT1-receptor messenger RNA in spleen, peripheral blood leukocytes and lung. In normal human lung, expression of the CysLT1-receptor mRNA was confined to smooth muscle cells and tissue macrophages. Finally, we mapped the human CysLT1-receptor gene to the X chromosome.

PMID: 10391245

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Reply about 1 year ago on Apr 27, 2008 by lanaw, #7671

This sounds very interesting. I am a researcher in a genetics lab dealing with chromosome deletions and we send samples to CHOP (Children's Hospital of Philadelphia). It may be worth those looking for more answers to check into it. It is amazing what one can determine from one small sample and run it on an CGH array.

As for me and my daughter, I did want to let everyone know that I took my daughter off of Singulair on April 2nd. To bring every one up to speed, my Master's of Science degree is in Toxicology so after educated research I felt very safe about using Singulair until now. My daughter was having extremely bad, (scream at the top of her lungs) nightmares. As I said we took her off Singulair on April 2nd, and April 7th was her last nightmare. She has not had one since, not even a bad dream! To summarize, there is definitely an issue with Singulair that needs to be addressed, especially before giving it to children. I am very upset about putting my daughter through this.

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Reply about 1 year ago on Apr 28, 2008 by concernedcitizen, #7687

Thank you so much for sharing your knowledge and your experience with Singulair.

In my opinion, this is a drug with a very high number of variables that enter into the equation as to whether it will be effective for a particular patient and whether the patient will suffer adverse drug reactions and what kind of reaction.

I hope that you will be able to use your background to hang in here with us to get more information. Parents and patients need and deserve answers.

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