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So, for example, digoxin has a half-life (or t 1 / 2 ) of 24–36 h; this means that a change in the dose will take the best part of a week to take full effect. For this reason, drugs with a long half-life (e.g., amiodarone , elimination t 1 / 2 of about 58 days) are usually started with a loading dose to achieve their desired ...
[3] [2] According to the Fast Facts for the Triage Nurse handbook, the ESI algorithm is primarily used in the United States. [2] As of 2019, 94% of United States EDs use the ESI algorithm in triage. [1] The concept of a "resource" in ESI means types of interventions or diagnostic tools, above and beyond physical examination.
Instead, the half-life is defined in terms of probability: "Half-life is the time required for exactly half of the entities to decay on average". In other words, the probability of a radioactive atom decaying within its half-life is 50%. [2] For example, the accompanying image is a simulation of many identical atoms undergoing radioactive decay.
Usually, clearance is measured in L/h or mL/min. [2] Excretion, on the other hand, is a measurement of the amount of a substance removed from the body per unit time (e.g., mg/min, μg/min, etc.). While clearance and excretion of a substance are related, they are not the same thing.
It is possible to calculate the amount of a drug in the blood plasma that has a real potential to bring about its effect using the formula: D e = B ⋅ D a {\displaystyle De=B\cdot Da\,} where De is the effective dose , B bioavailability and Da the administered dose.
Alternatively, since the radioactive decay contributes to the "physical (i.e. radioactive)" half-life, while the metabolic elimination processes determines the "biological" half-life of the radionuclide, the two act as parallel paths for elimination of the radioactivity, the effective half-life could also be represented by the formula: [1] [2]
[2] [3] However, when a medication is administered via routes other than intravenous, its bioavailability is lower due to intestinal epithelium absorption and first-pass metabolism. Thereby, mathematically, bioavailability equals the ratio of comparing the area under the plasma drug concentration curve versus time (AUC) for the extravascular ...
Medical calculators arose because modern medicine makes frequent use of scores and indices that put physicians' memory and calculation skills to the test. [2] The advent of personal computers, the Internet and Web, and more recently personal digital assistants (PDAs) have formed an environment conducive to their development, spread and use.