p.o.
p.o. refers to drug administration via the oral route, i.e. by mouth.
pA2
pA2 is a measure of the potency of an antagonist. It is the negative logarithm of the molar concentration of an antagonist that would produce a 2-fold shift in the concentration response curve for an agonist.
paracrine
Pertaining to the release of hormones (or other signalling molecules) which diffuse over a relatively short distance to act on nearby cells to affect changes in their function, growth or behavior. Fibroblast growth factors, hedgehog proteins, Wnt proteins and TGF-β peptides are paracrine factors.
parent compound
The starting compound in a biotransformation reaction.
parenteral administration
Parenteral administration routes do not involve the gastrointestinal tract and include intravenous, subcutaneous, intracerebral, intrathecal and intramuscular injection or infusion. Parenteral administration facilitates systemic exposure to the drug. In emergency situations and intensive care medicine parenteral administration is the most rapid and reliable method of drug delivery.
pD2
pD2 is the negative logarithm of an EC50 or IC50 value.
pharmacodynamics
Refers to what an administered drug does to the body. It refers to the actions (beneficial or harmful) of the drug.
pharmacoeconomics
A branch of health economics that applies economic considerations to drug therapy.
pharmacogenetics
The study of the effect of individual genes on drug response or action.
pharmacogenomics
The study of the effect of the genome on drug response or action.
pharmacokinetics
Refers to what the body does to an administered drug. It encompasses drug absorption, distribution, metabolism, and excretion.
pharmacology
Broadly defined as the study of drugs. It encompasses both how the body handles a drug as well as what a drug does to the body.
phenotype
The observable physical traits or biochemical characteristics of an organism based on a combination of the organism’s genes and environmental factors.
pIC50
pIC50 is the negative logarithm of the IC50 value.
pKa
Defined as the negative log of the acid dissociation constant (Ka), it is a measure of the strength of an acid.
pKB
pKB is the negative logarithm of the KB value.
pKd
pKd is the negative logarithm of the Kd value.
pKi
pKi is the negative logarithm of the Ki value.
potency
Potency is a measure of the concentration of a drug at which it is effective.
primary prevention
Primary prevention aims to prevent disease before it occurs. Examples include immunization against infectious diseases, and the use of statins to prevent cardiovascular disease.
prodrug
A drug that requires activation, generally by biotransformation enzymes, to have its therapeutic effect. The parent compound does not have significant if any therapeutic activity.