Buying medicine onlineSome websites that sell medicine can be not state-licensed pharmacies or aren't pharmacies at all; or may give a diagnosis that is not correct and sell medicine that is not right for you or your condition; or won't protect your personal information. The medicines that sold online can be fake (counterfeit or 'copycat' medicines); can be too strong or too weak, or have dangerous ingredients, or have expired (are out-of-date), or haven't been approved or checked for safety and effectiveness, can be made using non-safe standards, or not safe to use with other medicine or products you use. You have to talk with your doctor and have a physical exam before you get any new medicine for the first time. Use only medicine that has been prescribed by your doctor or another trusted professional.
Drug interactions precautionsDrug interactions may make your drug less effective, cause unexpected side effects, or increase the action of a particular drug. Some drug interactions can even be harmful to you. Early in a drug's development, companies conduct research to detect or predict potential interactions between drugs. Experts evaluate the drug-interaction studies as part of assessing a drug's safety. When a drug is taken orally, it usually travels from the stomach to the liver, where it can be metabolized-the process of breaking down and removing chemicals from the body. Enzymes are complex proteins that act as catalysts in starting or speeding up chemical reactions. They cause a specific chemical change in other substances without being changed themselves. The most important enzymes in the liver that metabolize drugs are called the cytochrome P450 family of enzymes. These enzymes break down drugs when they pass through the liver or small intestine. A drug may affect these enzymes by inhibiting them, which causes reduced activity of the enzyme and a buildup of the drug in the body. Or drugs may "induce" the enzymes, which causes increased activity of the enzyme and a reduction of the drug in the body. This phase of research in test tubes, known as in vitro studies, allows researchers to perform drug-interaction studies in labs by testing a drug with other drugs that have the same route. This has made the research faster and more accurate. If two drugs go through the same enzyme, the presence of one drug can prevent the metabolism of the other. So this allows you to look at the worst-case scenarios and ask: 'What if we put this drug with that one, knowing that they have the same route?'" Not everything that happens in a test tube will become meaningful in humans, though. Results from these test-tube studies can tell us whether need to do further testing in people to find out if an interaction is clinically significant. Three phases of clinical trials in humans must happen before a drug can be marketed. Phase 1 studies focus on a drug's side effects and how the drug is metabolized and eliminated from the body. Phase 2 studies focus on a drug's effectiveness. And Phase 3 studies gather more information on safety and effectiveness, which includes using the drug in combination with other drugs. Over the last several years, there has been a substantial increase in the number of drug-interaction studies the FDA sees in new drug applications. If drug interactions are significant enough, they can prevent a drug from being approved by the FDA. If the agency determines that known drug interactions can be managed and that a drug's benefits outweigh the risks for the intended population, a drug will be approved. Drug-interaction information then goes into the drug's labeling in the sections on "clinical pharmacology," "precautions," "warnings," "contraindications," and "dosage and administration." Some antibiotics, such as rifampin, can lower the effectiveness of birth control pills. Sildenafil, the active ingredient in the erectile dysfunction drug Viagra, should not be taken with nitrates for heart treatment because of the potential for dangerously low blood pressure.
Understanding your medicinesThere are several types of risks from medicine use: a) The possibility of a harmful interaction between the medicine and a food, beverage, dietary supplement (including vitamins and herbals), or another medicine. Combinations of any of these products could increase the chance that there may be interactions. b) The chance that the medicine may not work as expected. c) The possibility that the medicine may cause additional problems. To obtain the benefits of riding in a car, you think through the risks. You consider the condition of your car and the road, for instance, before deciding to make that trip to the store. The benefit and risk decision is sometimes difficult to make. The best choice depends on your particular situation. You must decide what risks you can and will accept in order to get the benefits you want. Important: think it through and work together with your doctor, pharmacist, or other health care professional to better manage the benefits and risks of your medicines. You need keep an up-to-date, written list of ALL of the medicines (prescription and over-the-counter) and dietary supplements, including vitamins and herbals, that you use--even those you only use occasionally. You have to always tell your doctor if you are or might become pregnant, or if you are nursing a baby. Always ask questions about any concerns or thoughts that you may have. Ask your doctor always if there are interactions with any other medicines or dietary supplements (including vitamins or herbal supplements), beverages, or foods. Use the same pharmacy for all of your medicine needs, whenever possible. Before starting any new medicine or dietary supplement (including vitamins or herbal supplements), ask your doctor again if there are possible interactions with what you are currently using. Ask your doctor if there is anything you can do to minimize side effects, such as eating before you take a medicine to reduce stomach upset. You always have to pay attention to how you are feeling; note any changes. Write down the changes so that you can remember to tell your doctor, pharmacist, or other health care professional.

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