What is drug clearance rate?
What is drug clearance rate?
Clearance defined Drug clearance is concerned with the rate at which the active drug is removed from the body; and for most drugs at steady state, clearance remains constant so that drug input equals drug output. Clearance is defined as the rate of drug elimination divided by the plasma concentration of the drug.
How is drug clearance rate calculated?
Another equation can calculate clearance. Clearance is equal to the rate at which a drug is removed from plasma(mg/min) divided by the concentration of that drug in the plasma (mg/mL).
What is a low clearance drug?
Low extraction ratio. These drugs are not efficiently cleared by the liver and are extracted less avidly and incompletely from hepatic blood. Their clearance is relatively independent of hepatic blood flow, and is primarily determined by the intrinsic metabolizing capacity of the liver and by the free drug fraction.
Which substance has maximum clearance rate?
Organic acids such as para-aminohippuric acid (PAH) have the highest clearances of all substances because they are both filtered and secreted. Inulin has unique properties that make it the only substance whose clearance is exactly equal to the glomerular filtration rate (GFR).
How is clearance calculated?
Concept of Clearance The clearance of substance x (Cx) can be calculated as Cx = Ax /Px, where Ax is the amount of x eliminated from the plasma, Px is the average plasma concentration, and Cx is expressed in units of volume per time.
How is AUC clearance calculated?
Knowing the bioavailability and the dose, the clearance of the drug may be calculated by dividing the dose absorbed by the AUC. The clearance calculated is relatively independent on the shape of the concentration-time profile. This method gives precious information on the pharmacokinetic behavior of a drug on trial.
What is clearance rate pharmacokinetics?
In pharmacology, clearance is a pharmacokinetic measurement of the volume of plasma from which a substance is completely removed per unit time. Usually, clearance is measured in L/h or mL/min. The quantity reflects the rate of drug elimination divided by plasma concentration.
What is the difference between GFR and clearance?
Creatinine clearance ( CrCl ) is an estimate of Glomerular Filtration Rate ( GFR ); however, CrCl is slightly higher than true GFR because creatinine is secreted by the proximal tubule (in addition to being filtered by the glomerulus). The additional proximal tubule secretion falsely elevates the CrCl estimate of GFR .
How is maximum clearance calculated?
The maximum clearance of a fit is the difference between the upper bound of the orifice diameter and the lower bound of the shaft diameter. The minimum clearance meanwhile is the difference between the lower bound of the orifice diameter and the upper bound of the shaft diameter.
What factors affect drug clearance?
Factors that affect clearance are: body weight, body surface area, cardiac output, drug-drug interactions, genetics, liver and kidney function, and plasma protein binding.
What does clear clearance mean in pharmacology?
Clearance reflects the elimination of the drug from the body. This drug elimination generally results from liver metabolism and/or excretion by the kidneys. In order to be eliminated, a drug must be presented to the organs of elimination by the plasma flow.
What is the relationship between drug concentration and clearance?
The higher the drug concentration, the more drug is presented to the organs and thus can be eliminated. In other words, the rate of drug elimination is proportional to the plasma concentration. Clearance is precisely this coefficient of proportionality.
How do you calculate the renal clearance of a drug?
Thus, the renal clearance of drug X can be calculated as: ClX = kerenal/CA. In itself, the renal clearance of a drug provides limited information on the way that a drug is handled by the kidneys unless it is compared to the renal clearance value(s) of a known compound(s) with specific renal excretion characteristics.
Does drug clearance increase during renal replacement therapy (RRT)?
Because RRT replaces renal function, it is clear that drug clearance during RRT is clinically relevant only with those drugs for which renal clearance is normally dominant (i.e., ≥30% of the total body clearance).