chemotherapy
Drug treatment of parasitic or neoplastic disease in which the drug has a selective effect on the invading cells or organisms.
Cheng-Prusoff equation
The Cheng-Prusoff equation is used to determine the Ki value from an IC50 value measured in a competition radioligand binding assay:
Where [L] is the concentration of free radioligand, and Kd is the dissociation constant of the radioligand for the receptor.
chromatin
A complex of DNA and proteins within the nucleus of mammalian cells.
clearance rate
Often simply called drug clearance, this is a measure of the efficiency of solute removal by the body or specific organs (e.g., the liver or kidney). When an organ is not specified, it refers to the total body clearance rate.
clearance/drug clearance
A fundamental pharmacokinetic term that refers to the ability of the body to eliminate a drug. The term is borrowed from renal physiology and is based on the concepts developed for creatinine clearance. It is defined as: Clearance = (rate of elimination)/ (concentration of drug in biofluid). The biofluid can be blood, plasma or other relevant fluid. Total body clearance is the sum of clearance by renal, liver and other drug elimination mechanisms.
Cmax, Cmin
Cmax is the maximum or 'peak' concentration of a drug observed after its administration. The Cmin, or trough concentration is observed after drug administration and just prior to the administration of a subsequent dose.
cohort studies
Cohort studies provide the best information about causation of disease and the most direct measurement of the risk of developing a disease or condition. They begin with a group of people who are free from disease but have been exposed to a potential cause. The cohort is then followed up to monitor the subsequent development of new cases.
compartment(s)
The space or spaces in the body, which a drug appears to occupy after it has been absorbed. Compartments in which equilibrium is achieved relatively late are referred to as “deep” compartments; compartments in which equilibrium is achieved early – and from which drug is redistributed to other sites – are referred to as “shallow” or “superficial” compartments.
concentration
In clinical settings, this is defined as an amount of drug per defined volume of body fluid. It is often expressed as a mass of drug per mL of plasma or serum.
cross-over experiment
A form of experiment in which each subject receives the test preparation at least once, and every test preparation is administered to every subject. At successive experimental sessions each preparation is “crossed-over” from one subject to another. The purpose of the cross-over experiment is to permit the effects of every preparation to be studied in every subject, to allow for the effects of individual differences in response.