Pharmacology — Drug Classifications

Agonist

A substance that activates a receptor to produce a biological response.

Antagonist

A substance that interferes with or inhibits the physiological action of another.

Therapeutic index

The ratio between the toxic dose and the therapeutic dose of a drug.

What is the mechanism of action of statins?

Statins inhibit HMG-CoA reductase, the enzyme involved in the synthesis of cholesterol, thereby lowering blood cholesterol levels.

Prodrug

A drug that is administered in an inactive form and is metabolized in the body to produce an active compound.

Enzyme induction

The increase in enzyme activity that results in greater metabolism of drugs.

Enzyme inhibition

The decrease in enzyme activity that results in reduced metabolism of drugs.

What is the role of cytochrome P450 enzymes?

Cytochrome P450 enzymes are involved in the metabolism of many drugs, affecting their activation or deactivation.

Volume of distribution

The theoretical volume that a drug would have to occupy to provide the same concentration as in the blood plasma.

Loading dose

An initial higher dose of a drug given to rapidly achieve a therapeutic concentration in the body.

Maintenance dose

The dose of a drug that maintains or keeps the drug in the therapeutic range.

Pharmacogenomics

The study of how genes affect a person's response to drugs.

What is the significance of the blood-brain barrier in pharmacology?

The blood-brain barrier restricts the passage of substances from the bloodstream into the brain, affecting drug delivery and effectiveness.

Potency

The amount of drug needed to produce a given effect.

Efficacy

The maximum effect that can be achieved with a drug, regardless of dose.

What are beta blockers used for?

Beta blockers are used to manage cardiac arrhythmias, protect the heart after a heart attack, and treat hypertension.

Tachyphylaxis

A rapid decrease in response to a drug after initial or repeated use.

Therapeutic window

The range of drug doses which can treat disease effectively while staying within the safety range.

What is the mechanism of action of ACE inhibitors?

ACE inhibitors block the conversion of angiotensin I to angiotensin II, leading to vasodilation and reduced blood pressure.

Additive effect

The effect of two chemicals is equal to the sum of the effect of the two chemicals taken separately.

Synergistic effect

The effect of two drugs taken together is greater than the sum of their separate effects.

What are the primary routes of drug excretion?

Drugs are primarily excreted via the kidneys (urine), liver (bile), lungs (exhalation), and skin (sweat).

Enterohepatic circulation

The recycling of drugs and other substances by the circulation of bile through the intestine and liver.

What is the role of P-glycoprotein in drug resistance?

P-glycoprotein is a transporter protein that pumps drugs out of cells, often leading to decreased drug efficacy and drug resistance.

What is an example of a drug with a narrow therapeutic index?

Warfarin, a common anticoagulant, has a narrow therapeutic index and requires careful monitoring.

Placebo effect

A beneficial effect produced by a placebo drug or treatment, which cannot be attributed to the properties of the placebo itself.

What is the action of diuretics?

Diuretics increase the excretion of water and salts from the body, often used to treat hypertension and edema.

Bioequivalence

When two drugs have the same bioavailability and same effect at the site of physiological activity.

First-order kinetics

A constant fraction of the drug is eliminated per unit time, leading to a logarithmic decrease in drug concentration.

Zero-order kinetics

A constant amount of drug is eliminated per unit time, leading to a linear decrease in drug concentration.