Which organ is associated with drug clearance?
For drugs that are eliminated by first-order kinetics, clearance is constant. Clearance by the kidneys is called renal clearance, and that by all other organs is referred to as nonrenal clearance. The latter most often represents clearance by the liver.
How is drug clearance calculated?
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.
What two organs are used for drug elimination?
Many organs in the body have the capacity for drug elimination, including drug excretion and biotransformation. The kidneys and liver are the most common organs involved in excretion and metabolism, respectively.
What organ S is are most predominantly involved with the clearance of medications?
Kidneys. The greatest proportion of drug excretion occurs through the kidneys. The liver makes most drugs and remedies water soluble for removal via the kidneys (see Figure 17.1, p.
What four routes are drugs excreted?
These organs or structures use specific routes to expel a drug from the body, these are termed elimination pathways:
What is a high clearance drug?
High extraction ratio. These drugs are rapidly and extensively cleared from the blood by the liver (e.g. in a single pass). Their clearance depends primarily on hepatic blood flow, and binding to blood components is not an obstacle for extraction; the extraction is said to be non-restrictive or blood flow dependent.
What’s the difference between clearance and the rate of drug elimination?
Clearance is defined as ‘the volume of blood cleared of drug per unit time’. Drug elimination rate is defined as ‘the amount of drug cleared from the blood per unit time’ In first order kinetics, elimination rate is proportional to dose, while clearance rate remains independent of the dose.
Which body tissues or fluids are routes of drug elimination?
Renal excretion is the most common route of drug elimination. However, many drugs are excreted into bile via the liver and some volatile substances (primarily gaseous anesthetics) can be excreted via the lungs.
What are the 4 pharmacokinetic principles?
There are four main components of pharmacokinetics: liberation, absorption, distribution, metabolism and excretion (LADME). These are used to explain the various characteristics of different drugs in the body.
Which drug is excreted in saliva?
Drug Excretion Drugs excreted in saliva include caffeine, phenytoin, and theophylline. Transfer of drugs from plasma into saliva appears to be largely dictated by passive diffusion. Because of this, only drugs in plasma that are not bound to proteins will be able to diffuse into saliva.
What is apparent clearance?
Equal to the drug dose divided by the area-under-the-curve. Used in pharmacokinetic trials where bioavailability is unknown.
What is the formula for single organ clearance?
Single organ clearance– CL = ER * Flow [L/h = frcn x L/h] Notice that there are no “mass” terms in the final CL formula. It is the “virtual” volume (in liters) of plasma completely cleared of drug per hour in this case.
How is the total clearance of a drug determined?
Total clearance is the sum of all body clearances. The same factors that determine renal and hepatic elimination of drugs affect drug clearance. Clearance (Cl) is mathematically defined as excretion rate/plasma concentration.
Which is the organ that removes drugs from the body?
Clearance of drugs from the body is the sum of clearance from every organ (renal clearance + hepatic clearance + clearance from other organs). The kidney is the major organ for removing drugs from the body.
What is the definition of clearance in medicine?
Clearance represents the capacity for drug removal by various organs and is defined as the volume of blood from which all drug is removed per minute (mL/minute). Both clearance and distribution volume are model-independent parameters.