Dose and dosage are terms commonly interchanged in both the language of sports science as well as that of everyday speech. A dose is the specific quantity of a therapeutic agent to be administered in a given instance, such as a drug or a medicine that is measured to be taken at one time. Dosage is a broader term that represents both the size of the dose in question as well as the intervals at which the dose is to be taken. As an example, when penicillin is prescribed to combat an infection, the stated dose might be 10 mg, while the dosage, considered the rules for the administration of the penicillin, could be set as 10 mg to be taken three times per day.
Doses are commonly, but not exclusively, used in reference to prescription medications, which are those substances legally available through the direction of a medical doctor. The consumption of sports supplements is often referred to in measurements that include references to dose. Further, many sport supplements, particularly those that include vitamin and mineral components, are described as containing specified percentages of the recommended daily allowance (RDA) of a particular nutrient.
Closely allied to the concepts of dose and dosages is that of an overdose, in which a person accidentally or deliberately ingests an amount in excess of the prescribed recommended limit of a particular substance. In most circumstances, an overdose is a poisoning of one or more of the body's systems, creating a toxic concentration in the bloodstream or the organs of the body.
The determination of an appropriate dose to be administered is partly a medical determination, made by the prescribing physician, and partly the result of scientific testing and development by the manufacturer of the product. Before a drug may be marketed in most countries of the world, the drug and its anticipated effect on the body must be tested, using human subjects. The investigative process is generally referred to as the clinical trial, or the clinical study, of the drug in question. A clinical trial will ultimately assist the manufacturer in determining precisely how the product is absorbed, metabolized, and excreted from the body. The trial will also determine how the drug interacts with other known medications.
The clinical trial begins with experimental testing that, if successful, will lead to preclinical testing with animals, to assess the effect on live subjects. If the preclinical testing shows sufficient promise, three stages of clinical tests will be conducted: one, to ascertain safe human use; two, the sampling of a broader range of human subjects; and three, to expand the human subject range and to finalize dosages to be recommended.
A failure to adhere to any government- or regulatory agency-imposed guideline regarding the conduct of the clinical trial and the corresponding determination of the appropriate recommended dosage for a drug will result in the product not being approved for human use.
The dosages and the otherwise recommended amounts for other sport supplements are usually subject to the same level of testing as are new pharmaceutical products. Dietary supplements, including the nutritional and vitamin products used by athletes, may set out the percentage of the RDA that the product contains in any given vitamin or mineral. However, the amounts recommended for athletic consumption are those of the manufacturer, not as approved by a regulatory agency. As of 2005, dietary supplements are not subjected to the requirements of a government regulatory agency, and so have not generally been scrutinized as vigorously for what substances may be disguised or not displayed on an exterior label.
In some circumstances, particularly with respect to over-the-counter (OTC) medications, there is a temptation on the part of an athlete to conclude that if the stated recommended dosage for the product is "x," in some circumstances two times "x" or three times "x" or even more at a given time will consequently provide a greater benefit. Overdoses can occur as readily with such products as may otherwise result for prescription drugs.
Multivitamin preparations are a further example of the potential for over-consumption. When an athlete believes that, due to hard training or dietary lapses, they are not receiving the optimal daily amount of vitamins through diet, the athlete may ingest larger amounts of vitamins by way of supplements to make up the perceived shortfall. Many of the vitamins in a multivitamin product are water soluble, meaning that they are not retained in the system but are flushed out by the renal (kidney) system through urine. Many multivitamin products are manufactured to contain significant amounts of minerals; excess multivitamin consumption above the recommended amount may lead the athlete to inadvertently consume large amounts of minerals such as iron and calcium, which are not readily flushed and which can collect in toxic amounts within the body.
Commonly available analgesics such as aspirin and ibuprofen can also lead to troubles for the athlete. These products, often ingested to relieve minor pain or muscle soreness, can cause significant physical problems, including pronounced stomach distress and convulsions, especially when the recommended amount is not followed.