FUNDAMENTAL PRINCIPLES OF PHARMACOLOGY

Comprehensive vocabulary flashcards covering the fundamentals of veterinary pharmacology, including pharmacodynamics, pharmacokinetics, and specific systems-based drug classes.

Pharmacology

An experimental science dealing with the properties of drugs and their effects with living system; derived from Gk. Pharmacon (drug) and Lat. Logos (study).

Drug

Any article intended to be used in diagnosis, mitigation, treatment, or prevention of disease in humans and animals, and any article other than food intended to affect the structure or function of the body.

Pharmacodynamics

The science and study of how drugs produce effects on living organisms; the study of the response of an organism to the action of drugs in the absence of disease.

Pharmacokinetics

The mathematical description of temporal changes in concentration of drugs and/or their metabolites within the body.

Chemotherapy

The use of drugs that selectively inhibit or destroy specific agents of disease such as bacteria, viruses, fungi, and other parasites, centered on the notion of selective toxicity.

Toxicology

The study of poisons and the adverse effects of xenobiotics, or the science that defines the limits of safety of chemical agents for human and animal populations.

Posology

The study of medicine dosage, which varies with species, intended drug effect, and individual tolerance.

Dose vs. Dosage

A dose is the quantity of medication administered at one time, whereas dosage refers to the determination and regulation of doses.

Metrology

The study of weights and measures as applied to the preparation and administration of drugs.

Pharmacognosy

The branch of pharmacy concerned with the study of the sources of drugs.

Pharmacogenomics

The study of genetic variations that cause differences in drug response among individuals or populations.

Selective Toxicity

The principle where a given dose of a drug may be poisonous to one organism (like a parasite) but not to another (the host).

Drug Receptor

The macromolecular component of body tissue (proteins, enzymes, nucleic acids) with which a drug interacts to initiate its pharmacologic effects.

Ligand

Any drug or substance with specific affinity to a receptor.

Agonist

A drug that possesses affinity for a particular receptor and causes a change that results in an observable effect (affinity with efficacy).

Affinity

The tendency of a drug to combine with a particular kind of receptor.

Efficacy (Intrinsic Activity)

The maximal effect a drug can produce.

Potency

The dose that must be administered to produce a particular effect of a given intensity.

Antagonist

A drug that blocks the response produced by an agonist and is devoid of intrinsic activity.

Competitive Antagonist

An antagonist that competes with an agonist for the same site; the effect is completely reversible by increasing the concentration of the agonist.

Noncompetitive Antagonist

An antagonist where the agonist has no influence on the degree of antagonism or its reversibility; conceptually removes the receptor or response potential from the system.

Dualist

A drug having both agonistic and antagonistic properties; typically a partial agonist compared to a full agonist.

Drug Action vs. Drug Effect

Drug action refers to where and how the effect is produced (initial interaction), while drug effect is the succeeding consequence of that interaction.

Idiosyncratic Reaction

An unpredictable adverse drug effect due to genetic differences in a patient, which may occur on the first exposure to a drug.

Therapeutic Index (TI)

The ratio of median lethal dose ($LD_{50}$) to the median effective dose ($ED_{50}$), calculated as $TI = \frac{LD_{50}}{ED_{50}}$; higher values indicate safer drugs.

Bioavailability (F)

The fraction of unchanged drug reaching the systemic circulation intact; for intravenous doses, $F = 1$ (or 100%).

Apparent Volume of Delivery ($V_{d}$)

The proportionality constant relating the plasma drug concentration to the total amount of drug in the body.

Physiologic Disposition

The movement and changes a drug undergoes within the body, including the processes of absorption, distribution, biotransformation, and excretion.

Biotransformation

Biochemical processes that convert drugs into more water-soluble (polar) chemicals to enhance excretion and reduce the volume of distribution.

Phase I Biotransformation

Metabolic transformation via oxidation, reduction, or hydrolysis, often occurring in hepatic microsomes.

Phase II Biotransformation

Synthetic reactions conjugating Phase I products with endogenous metabolites such as glucuronide, acetate, or glutathione.

Half-time ($t_{1/2}$)

The time required for a drug concentration to reduce to half of its initial concentration, calculated as $t_{1/2} = \frac{0.693}{k}$.

Clearance ($CL_{B}$)

The volume of blood effectively cleared of a drug in a specified period of time; the single most important factor determining drug concentrations.

Total Body Clearance

The volume of blood effectively cleared of a drug in a specified period of time, expressing the rate of drug removal from the body.

Entero-hepatic Recycling

A process where glucuronide-conjugated drugs excreted in the bile are reactivated by gut microflora and reabsorbed into the circulation.

Adrenergic (Sympathomimetic)

Drugs that produce physiologic responses similar to the stimulation of the sympathetic nervous system, mimicking epinephrine and norepinephrine.

Cholinergic (Parasympathomimetic)

Drugs that mimic the action of acetylcholine or inhibit its breakdown, resembling the stimulation of parasympathetic nerves.

Hypnotic

A narcotic agent used to induce a state of sleep from which a subject can be easily aroused.

Sedative

A narcotic agent used to calm a nervous, vicious, or excited subject, often causing drowsiness.

Tranquilizer (Ataractic)

A substance that produces sedation without causing drowsiness.

Minimum Alveolar Concentration (MAC)

The minimum alveolar concentration of an inhalant anesthetic that prevents purposeful movement in 50% of patients responding to a painful stimulus.

Local Anesthesia

A reversible loss of perception of pain in a local or regional part of the body, not accompanied by loss of consciousness.

Opioid

Substances that bind specifically to opioid receptors (Mu, Kappa, Sigma) in the brain to produce analgesia and potentially narcosis.

NSAIDs

Non-steroidal anti-inflammatory drugs that block the cyclooxygenase (COX) enzyme necessary for prostaglandin formation.

Expectorant

Agents that increase the volume and fluidity of secretions in the respiratory tract to encourage movement of debris.

Mucolytics

Agents, such as acetylcysteine, that liquefy mucus plugs and debris in the respiratory tract.

Antitussives

Drugs used to reduce coughing by depressing the cough center in the brain or soothing respiratory mucus membranes.

Glucocorticoids

Adrenal cortex hormones synthesized from cholesterol that affect energy metabolism, immune response, and decrease capillary permeability.

Insulin

Hormone produced by pancreatic beta cells that facilitates cellular uptake and metabolism of glucose.

Luteolysis

The regression of the corpus luteum, mediated by Prostaglandin F2$\alpha$ ($PGF_{2\alpha}$) to decrease circulating progesterone.

Oxytocin

A hormone used to induce parturition, mediate milk let-down, and evacuate uterine secretions.