Drug metabolism (Biotransformation) Drug metabolism describes the process by which the body breaks down and converts medications into active chemical substances (metabolites). Metabolism refers to the sum of all physical and chemical processes occurring in the body that maintain life. The primary site of drug metabolism is the liver. This organ plays a substantial role in metabolism, digestion, and elimination of substances from the body. Enzymes in the liver are responsible for chemically changing drug components into substances known as metabolites . Metabolites bind to other substances in the body for excretion through the lungs, reabsorption by the intestines, or through bodily fluids including saliva, sweat, breast milk, and urine. The main mode of excretion from the body is through the kidneys. A number of isoenzymes in the liver are necessary for drug metabolism. Each has a catabolic action on substances, breaking them down into metabolites. Through this action, they lower the concentration of medication in the bloodstream (Susa et al., 2023). Drug interactions Drugs can interact with other drugs, foods, and beverages. Interactions can lessen or magnify the desired therapeutic effect of a drug or may cause unwanted or unexpected side effects. There are thousands of possible drug-to-drug and drug-to-food interactions, and many medications and supplements are contraindicated under certain conditions or in patients with specific diseases and disorders. This is why it is imperative that patients always keep their physician fully informed about all drugs and dietary supplements (including herbal remedies) they are taking. Metabolic rates also vary significantly from person to person. A drug dosage that works quickly and effectively in one individual may not work well in another. Genetic factors as well as environmental variables, nutrition, and age also influence drug metabolism. For example, infants and elderly individuals may have a reduced capacity to metabolize certain drugs, requiring an adjusted dose. Foods and beverages that interact with drugs include: ● Grapefruit juice : Grapefruit juice inhibits the metabolism of many medications, including cyclosporine, felodipine, nifedipine, nitrendipine, nisoldipine, carbamazepine, triazolam, and midazolam. ● Foods and beverages with tyramines : Red wine, malted beers, smoked foods (e.g., fish and meats), dried fruits, and aged cheeses may contain tyramines and can cause a severe and dangerous elevation in blood pressure when taken with MAOI inhibitors (a class of antidepressants). ● Caffeinated beverages : The caffeine contained in coffee and colas can influence drug metabolism. ● Alcohol : Alcohol is a central nervous system depressant and should not be taken with other CNS depressants (e.g., antipsychotics, antihistamines). In addition, certain fermented beverages may also contain tyramines. ● Dairy products : Milk, cream, and other dairy products containing calcium can prevent the absorption of antibiotics such as tetracycline, doxycycline, and ciprofloxacin when they are taken with drugs. In addition, whole milk with vitamin D can cause milk- alkali syndrome in patients taking aluminum hydroxide antacids. (Bushra et al., 2011) Herbal Supplements and Vitamins . There so far is not a lot of research as to adverse effects of herbal supplements and massage therapy. There are however some studies about their effects combined with medications or for specific medical conditions. Again, as a manual therapist it is not
within your scope of practice to be able to give advice or recommendations as to which herbal supplements and vitamins may be beneficial or detrimental to your client. If your client is taking an extreme regiment of herbs, supplements, or vitamins for a specific condition, you can speak to their herbalist or acupuncturist or herbalist first before performing any deep tissue techniques. Herbal supplements also produce adverse drug interactions. In 2000, the Food and Drug Administration (FDA) issued a warning on the popular herb St. John’s wort, commonly used to treat depression. The supplement was found to inhibit the effect of indinavir, a protease inhibitor used in the treatment of HIV. It may also affect the action of cyclosporine and other protease inhibitors. Other herbs that may interact with mainstream medications include gingko biloba, ginseng, and garlic, all of which may heighten the blood thinning effect of the anticoagulant warfarin. Because herbs are regulated by the FDA as dietary supplements, they do not require the same extensive clinical trials and premarket testing that drugs do before they are accepted for sale in the United States. Potential interactions and adverse effects associated with herbal supplements are a distinct danger, and individuals who experience serious side effects from dietary supplements should report them to FDA's MedWatch program (Hussain, 2011). In some cases, adverse drug reactions may be difficult to detect, closely resembling the symptoms of the disease or condition the medication was prescribed to treat. Patients who take a number of medications or self-treat with over- the-counter drugs and/or herbal remedies may not be able to determine which drug actually triggered the interaction. A 2017 study found that 35 percent of respondents participating disclosed their use of herbal supplements to their healthcare providers (Rashrash, 2017). In cases where a serious drug or herb interaction occurs, withholding this information can delay diagnosis and put the patient at increased risk. Patients with chronic health conditions, particularly those with liver disorders, should always inform their healthcare professional before taking any over-the-counter medications or dietary supplements. Because of the risk for a drug-to- drug interaction, individuals should also let their doctor know if they are taking drugs prescribed by other physicians. Individuals should closely follow instructions for use and package directions on both prescription and over- the-counter drugs. Consulting with a pharmacist and/or physician may be beneficial if package directions are unclear to the patient. In general, grapefruit juice should not be taken with medication unless recommended by a doctor. Patients taking MAOI inhibitors should always check food and beverage labels to ensure tyramines aren’t included and should avoid all fermented drinks. Human variation to drug responsiveness Humans vary considerably in the degree to which they respond to drugs. One individual may even respond differently to the same drug at different points in time. In some cases, an individual will respond in an unusual or idiosyncratic way. These effects may be associated with genetic differences in how the body processes the drug or, in some cases, immunologic mechanisms, known as allergic reactions . In such cases, the individual is considered hypersensitive to the drug. There are also individuals who react much less (hyporeactive) or more intensely (hyperreactive) than the vast majority of those given the same dose. In some cases, the degree of response changes during the course of
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