Bioavailability of the active ingredient
When you are administering medication, the medicine's active ingredient should reach the intended site of action in the patient's body in order to develop its effect there. But this is not always easy - depending on the dosage form, some is lost en route, whether through metabolism, excretion, lack of absorption or the "first-pass effect." Bioavailability is a term used in pharmacology and is a measure of how much active ingredient actually reaches the patient. In other words, it describes how quickly and to what extent an active ingredient is absorbed and is available at the site of action. The more of the active ingredient is absorbed unchanged and reaches the systemic circulation, the higher the bioavailability of the administered drug. The bioavailability of medicines is an important measure for correct dosing. If only 50% of the active ingredient can be absorbed, the dosage must be doubled accordingly.