Aspirin why 81 mg

Methods: To achieve this goal, we have studied the effects of these two dosing regimens on platelet function in healthy women meeting the WHS inclusion criteria using a randomized design. We enrolled 49 healthy female volunteers and used a sequential, crossover design to compare the two regimens.

The participants received a day course of each aspirin-dosing regimen separated by a 7-day washout period. The degree of platelet inhibition was measured on days of each dosing regimen using a point-of-care platelet function assay utilizing arachidonic acid to activate platelets VerifyNow-Aspirin.

One dosage stands out from the others. While most medications come in dosages of round numbers or common decimals, low-dose aspirin has a standard dose of 81 mg. Why is aspirin available at a dose of 81 milligrams? The answer is historical in nature and is rooted in a medieval and now defunct system of measurement called the apothecary system of weights and measures. The full explanation of aspirin 81 requires some background information on the apothecary system and is best explained in comparison to the more familiar metric system.

The apothecary system of weights and measures was developed and formalized in England and France during the early Middle Ages.

This system came to be used for medication dosages before the development of the now-standard metric system in the late s. In the metric system, mass is based on the kilogram, with other units defined relative to the kilogram. For example, the gram is one one-thousandth of a kilogram, and one milligram is one one-millionth of a kilogram. In the apothecary system, the base weight was derived from the weight of a grain of barleycorn.

This unit was creatively termed the grain, abbreviated gr. The grain was used to define the larger units in the apothecary system. England and France both used scruples, drams sometimes written as drachme , ounces, and pounds as larger units built from the grain.

However, the countries defined the units differently. In France, 24 grains formed 1 scruple, while in England, 20 grains formed 1 scruple. One English pound weighed gr, and one French pound weighed gr. Of note, the barleycorn grain has a history of being used to derive other units. Aspirin is one of the oldest, most widely used drugs in the world. Taken for pain relief for over 2, years, its active ingredient, salicin, is in the leaves and bark of the willow tree.

In , the Bayer company in Germany developed a synthetic version called acetylsalicylic acid and named it aspirin.

The regular adult dosage is mg taken every 4 hours when needed to treat pain, inflammation, and fever caused by a variety of ailments. Low-dose aspirin refers to dosages between 81 mg and mg taken every day to prevent heart attacks, strokes, and colon cancer. Most heart attacks and strokes happen when a blood clot forms and blocks blood flow in an artery. Under normal circumstances, the body develops a blood clot to stop the loss of blood after an injury.

When a blood vessel is damaged, sticky cells called platelets begin to clump together, while proteins in the blood form strands of fibrin. The fibrin creates a net-like structure that holds the forming clot together.

Blood clots can form in damaged vessels of the heart or the brain, and these can block blood to the tissue and cause a heart attack or stroke. Aspirin stops clots from forming by preventing the platelets from clumping together.