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Clearance of a substance is sometimes expressed as the inverse of the time constant that describes its removal rate from the body divided by its volume of distribution (or total body water). In steady-state, it is defined as the mass generation rate of a substance (which equals the mass removal rate) divided by its concentration in the blood.
In survival analysis, the hazard ratio (HR) is the ratio of the hazard rates corresponding to the conditions characterised by two distinct levels of a treatment variable of interest. For example, in a clinical study of a drug, the treated population may die at twice the rate of the control population.
For example, gentamicin is an antibiotic that can be nephrotoxic (kidney damaging) and ototoxic (hearing damaging); measurement of gentamicin through concentrations in a patient's plasma and calculation of the AUC is used to guide the dosage of this drug. [3] AUC becomes useful for knowing the average concentration over a time interval, AUC/t.
The elimination rate constant K or K e is a value used in pharmacokinetics to describe the rate at which a drug is removed from the human system. [1] It is often abbreviated K or K e. It is equivalent to the fraction of a substance that is removed per unit time measured at any particular instant and has units of T −1.
The formula for calculating the absolute bioavailability, F, of a drug administered orally (po) is given below (where D is dose administered). F a b s = 100 ⋅ A U C p o ⋅ D i v A U C i v ⋅ D p o {\displaystyle F_{\mathrm {abs} }=100\cdot {\frac {AUC_{\mathrm {po} }\cdot D_{\mathrm {iv} }}{AUC_{\mathrm {iv} }\cdot D_{\mathrm {po} }}}}
One computational method which can be used to calculate IV estimates is two-stage least squares (2SLS or TSLS). In the first stage, each explanatory variable that is an endogenous covariate in the equation of interest is regressed on all of the exogenous variables in the model, including both exogenous covariates in the equation of interest and ...
The Karvonen method factors in resting heart rate (HR rest) to calculate target heart rate (THR), using a range of 50–85% intensity: [10] THR = ((HR max − HR rest ) × %Intensity) + HR rest Example for someone with a HR max of 180 and a HR rest of 70:
For example, a person weighing 75 kg with burns to 20% of his or her body surface area would require 4 x 75 x 20 = 6,000 mL of fluid replacement within 24 hours. The first half of this amount is delivered within eight hours from the burn incident, and the remaining fluid is delivered in the next 16 hours.