Glossary
ICP Glossary
Select a letter to jump to that section of the glossary.
A
Ab:
Amount of drug in the body.
ADE:
Adverse drug event. Any actual or potential damage resulting from medical intervention related to medicines.
ADR:
Adverse drug reaction. Any response to a drug which is noxious, unintended, and occurs at doses used in man for prophylaxis, diagnosis or therapy.
AUC:
Area under the plasma concentration curve vs time curve.
B
Biophase:
The immediate vicinity of the site of activity of a drug.
C
CBA:
Cost-benefit analysis.
CEA:
Cost-effectiveness analysis.
Clearance:
The volume of plasma cleared of drug per unit time. Or a constant relating the rate of elimination to the plasma concentration.
Clinical Pharmacology:
The principles behind the prescribing process.
CMA:
Cost-minimization analysis.
Cmax:
Maximum concentration.
Compliance:
In drug therapy this describes how much a patient is able to follow a full course of medication exactly as prescribed.
Concordance:
This is the more modern, less authoritarian, interpretation of compliance that recognizes that a prescription embraces an agreement between the patient and the doctor.
Cp:
Plasma concentration.
Cp0:
Plasma concentration at time zero.
CPss:
Plasma concentration at steady state.
Cpt:
Plasma concentration at time t.
CrCl:
Creatinine Clearance.
CUA:
Cost-utility analysis.
CYP:
Cytochrome P450.
D
Dose Interval:
The time interval between administration of doses.
Dose Tapering:
Back-titration of a dose of a drug after effect has been achieved in order to achieve the minimum dose commensurate with desired effect.
E
e:
The natural logarithm (value = 2.7183)
EC50:
The concentration of a drug at which effect is 50% maximum.
Emax:
The maximum effect of a drug.
F
F:
Fractional oral availability.
First-order:
A number to the power of one. In pharmacokinetics, it refers to elimination that is dependent on concentration (i.e. Cp1 = Cp), as occurs with most drugs.
First-pass metabolism:
Metabolism that occurs between the gut lumen and the systemic circulation during the first passage of the drug through the gut wall, the portal system and the liver to the inferior vena cava.
Flow-dependent elimination:
The elimination of high clearance drugs is so rapid that it is susceptible to the rate of presentation to the eliminating organ, and hence to blood flow.
fe:
Fraction excreted unchanged by the kidney.
G
H
Half-life:
The time for the concentration of the drug in the plasma (or the amount of drug in the body) to halve.
I
J
K
k:
Rate constant of elimination: The fraction of drug removed per unit time. Applies to drugs with first-order elimination (i.e. most drugs).
Km:
The Michaelis constant. The concentration at which the rate of reaction is half the Vmax.
L
ln:
The natural logarithm.
Loading dose:
The dose required to achieve a target plasma concentration as soon as possible.
M
M/P ratio:
Milk to plasma ratio.
MEC:
Minimum effective concentration.
MTC:
Minimum toxic concentration.
N
O
OTC:
Over the counter.
P
P.B.:
Protein Binding - usually expressed as a fraction or percentage.
pH:
The negative of the log (base 10) of the concentration of hydrogen ions.
Pharmacodynamics:
The study of drug effect, and mechanism of action, i.e. what the drug does to the body.
Pharmacokinetics:
The study of the movement of drug into, within, and out of the body, i.e. what the body does to the drug.
Phase I metabolism:
Simple chemical alteration of a molecule by oxidation (most commonly), reduction or hydrolysis. It occurs often by cytochrome p450 enzymes.
Phase II metabolism:
Conjugation reactions including glucuronidation (most common), acetylation, sulphation and metylation.
pH-dependent elimination:
Variation in renal elimination of drugs with susceptible pKa values whose degree of ionization varies within the range of pH values of the urine (pH 4.5-8).
PILs:
Patient information leaflets.
pKa:
The pH at which a drug is 50% ionized, and 50% unionized.
Potency:
An index of the concentration of a drug required for a given effect. The lower the concentration the greater the potency.
Prodrug:
A drug that is inactive in itself, but which is converted to an active metabolite.
Q
QALY:
Quality adjusted life years.
R
RCT:
Randomized controlled trial.
S
Saturable metabolism:
Drug concentrations rise disproportionately as a result of a change from first-order to zero-order elimination.
SIADH:
Syndrome of inappropriate antidiuretic hormone.
ss:
Steady state.
T
T1/2:
The half life.
Tachyphylaxis:
Literally means 'quick protection'. It refers to a rapid diminution of response to a drug, usually within minutes or hours.
TDM:
Therapeutic drug monitoring. Refers to the monitoring of drug concentrations as a surrogate for true pharmacodynamic end-points.
Teratogenicity:
Literally means propensity to form a 'monster'. It refers to the propensity of a drug to cause a fatal malformation.
Therapeutic index:
The ratio of concentration associated with toxicity vs efficacy.
Therapeutic range:
The range of drug concentrations associated with a reasonable probability of efficacy without undue toxicity in the majority of patients.
Therapeutics:
The process of medical treatment.
Tmax:
Time to maximum concentration.
Tolerance:
A gradual decline in effectiveness of a drug, usually over days or weeks, as a result of compensatory homeostasis (often receptor up or down regulation).
U
V
Vmax:
The maximum velocity of a chemical reaction.
Volume of distribution:
The volume into which a drug appears to distribute with a concentration equal to that of plasma. Or, a proportionality constant relating the plasma concentration to the amount of drug in the body.
W
X
Y
Z
Zero-order:
A number to the power of zero (i.e. always equals one i.e. X0=1). In pharmacokinetics, it refers to elimination dependent of concentration (i.e. Cp0=1), as occurs with ethanol.