Operating Hours: M-F 9-6pm EST quick search: over 10,000 products Prescription Prices Price Calculator Shopping Cart Current Order 0 items selected Medical Information Personalized Medicine Pharmacogenetic Testing Side Effects Weaning Off Medications Health Topics Bulletins Pharmacy.ca Using This Site About Us Certification Careers Contact Us This site complies with the HONcode standard for trustworthy health information: verify here. Tamoxifen - A Special Case Tamoxifen is a medication used to prevent the recurrence of breast cancer. Tamoxifen therapy is started after a patient has had her primary treatment (chemotherapy, radiation and/or surgery) and is usually taken for 2 to 5 years. Tamoxifen's role is to stop estrogen receptor positive breast cancer cells from duplicating. In this way it acts to help prevent a relapse of your cancer. Tamoxifen must be converted (metabolized) by your body into a much more active form to be most effective. In the case of tamoxifen it must be converted into endoxifen before it can exert its maximal preventative activity. Cytochrome P450 2D6 (CYP2D6) is a key enzyme that is responsible for the conversion of tamoxifen into endoxifen. There are two possible reasons why tamoxifen does not get converted to endoxifen. One is genetics, i.e. you may not be capable of producing an active CYP2D6 enzyme. The other reason is the ingestion of a substance, such as another medication, that inhibits or prevents the CYP2D6 enzyme from working properly. Sometimes it's a combination of both of these reasons. Since CYP2D6 is a key enzyme involved in converting tamoxifen into endoxifen, a fully functioning CYP2D6 system is very important. Your individual genetic make up determines how much CYP2D6 enzyme your body produces. The three most likely CYP2D6 genetic types that you may be categorized as are: For patients undergoing tamoxifen therapy, both 'poor' and 'intermediate' metabolizers are of concern. If you are a poor or an intermediate metabolizer you may not be able to convert enough tamoxifen to endoxifen to provide tamoxifen's expected cancer prevention function. Tamoxifen CYP2D6 Pharmacogenetic Testing SUMMARY - OVERVIEW This is a simple, in-office procedure. A cheek swab is taken by your doctor and sent to a certified testing laboratory. The results of this test will show whether you are capable of producing sufficient CYP2D6 functioning enzyme to convert tamoxifen into a very active form, endoxifen. Pharmacogenetic testing of the CYP2D6 system can determine your metabolizer type. This information will help your treating physician determine if tamoxifen is the best therapy for you. All that is needed for this test is for your doctor to collect two swabs of cheek cells from the inside of your mouth. The swabs resemble a Q-tip and the collection technique is as simple as twirling around the cotton end against the inside of your cheek. Your doctor then sends the swabs to us for processing and we send a written report to your doctor in about 10 days to 2 weeks. Tamoxifen CYP2D6 Interaction Monitoring Service SUMMARY - OVERVIEW The CYP2D6 Monitoring Service can provide you with a means of being aware when a new medication or herbal you start taking may negatively affect your bodies ability to convert tamoxifen into endoxifen, its most protective form. This service can provide you with the peace of mind that other medications you are taking or might take in the future will not inhibit the CYP2D6 enzyme and render tamoxifen less effective. The CYP2D6 Interaction Monitoring Service is provided by Pharmacy.ca's team of pharmacists and our medical director. While it is important to ensure that you have enough genetic capability to produce sufficient CYP2D6 enzymes, it is also important to ensure that other substances ingested while on tamoxifen do not inhibit the activity of these enzymes. Unfortunately some medications (prescriptions/over the counter medications/herbals) inhibit the CYP2D6 enzyme partially or completely. Since most patients take tamoxifen for an extended period (usually 2 to 5 years) it is quite common for patients to also start other medications during this period. New medications may be initiated by doctors other than your oncologist while you are on tamoxifen therapy. For example; your family physician, an emergency room doctor, or even a heart specialist might initiate therapy for a condition unrelated to breast cancer. Furthermore, you may self-initiate over the counter (non-prescription) medications, including herbal/natural product treatments. The problem with new treatments is that they may be initiated without the oversight of your oncologist or a pharmacist who is overseeing your entire medication regimen and specifically watching for CYP2D6 inhibitor conflicts that may arise. The usual corrective action when it is discovered that such an inhibitor medication is being taken at the same time as tamoxifen, is to find an alternative medication that does not inhibit the CYP2D6 enzyme and its action on the tamoxifen. The field of scientific research exploring which medications act as inhibitors of CYP2D6 is growing very rapidly. At Pharmacy.ca our medical director and team of pharmacists actively review scientific publications for new information on a continual basis and incorporate it into our counseling of patients taking tamoxifen. The service is a unique program of monitoring CYP2D6 inhibitors for patients on tamoxifen therapy. The idea is to provide you with the peace of mind that all your medications and herbals are being reviewed by a team of pharmacists to ensure you are not knowingly taking any substances that might lessen the protective benefits of your tamoxifen therapy. As a patient on tamoxifen you have a choice in how you access our Tamoxifen CYP2D6 Interaction Monitoring Service. You can choose to either; pay an annual fee and notify our pharmacists each time you start a new medication or herbal product. source your prescription and non-prescription medications and herbals from our pharmacy. In this case you are a patient of our pharmacy and the Tamoxifen CYP2D6 Interaction Monitoring Service is provided as a service at no additional fee. In addition to advising you of conflicts between new medications/herbals and tamoxifen therapy, we will also advise your prescribing physician of the problem and recommend that an alternative therapy be chosen that will not to interfere with tamoxifen's protective properties. Patients wanting more information about our CYP2D6 Interaction Monitoring Service are welcome to call any of our pharmacists, toll free at 1-800-727-5048, M-F 9-6 EST. Patients who wish to enroll in the Tamoxifen CYP2D6 Interaction Monitoring Service can do so online by clicking here. This will bring you to an enrollment page that also lists pricing options. The monitoring process can be started on this page by entering your personal data, any current medications you are taking along with any herbals and dietary supplements you may be using. | home | prescriptions | non-prescription medicine | vitamins, herbals & nutrition | personal care | | allergy medicine | excessive sweating| arthritis | smoking cessation | hair loss | back pain | medical tests | 311 Sherbourne St, Toronto, On M5A 3Y1 1-416-960-7768 OCP Accreditation number 17533, owner is Central Medical Pharmacy Inc. Designated manager is Veronique Koo, B Sc Phm. Pharmacists are available for counselling during operating hours. The information provided on our site is for general information purposes only and is not intended to qualify, supplement or replace that of your medical professional. 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