Basic Principles of Pharmacology (Part 3)

The use of various drugs according to their pharmacokinetics and pharmacodynamics requires a basic understanding of the principles. In short, pharmacokinetics describes the way the body treats a drug after it enters the body and aims to quantify the processes involved in the biodisposition of a drug, including absorption, distribution, metabolism, and elimination.

As part of this quiz, we will explore and learn more about the most commonly used terms in pharmacology to gain a better understanding of how drugs are measured and interact in the body.

  • Question of

    The dose of a drug or toxin at which toxicity occurs in 50% of cases.

    • Median toxic dose
    • Median effective dose
    • Potency
    • Therapeutic index

    Correct Wrong

    A median toxic dose (TD50) is defined as the dosage at which 50% of cases of toxicity occur. When used for practical purposes, this value should be accompanied by the type of toxicity. Toxicity need not be lethal, so the TD50 is typically lower than the median lethal dose (LD50).

  • Question of

    It is the amount of a lethal substance that will kill 50% of a given target population within a set time period.

    • Median lethal dose
    • Median toxic dose
    • Potency
    • Therapeutic index

    Correct Wrong

    The median lethal dose (or LD50) refers to the dose of a test substance that is lethal for 50% of the test animals in a given dose group. Commonly, LD50 is used to estimate a substance's acute toxicity. Lower LD50 indicates higher toxicity.

  • Question of

    Ratio of the highest dose of a drug that does not cause any toxicity to the dose that produces the desired effect.

    • Therapeutic index
    • Potency
    • Bioavailability
    • Half-life

    Correct Wrong

    A therapeutic index (TI; also called a therapeutic ratio) is a quantitative tool used to quantify the relative safety of a drug. The dosage of a therapeutic agent that produces a therapeutic effect is compared to the dose that leads to toxic effects.

  • Question of

    Indicates the extent to which a drug is distributed in body tissue rather than plasma.

    • Volume of distribution
    • Chirality
    • Median toxic dose
    • Median lethal dose

    Correct Wrong

    Rather than the plasma, a drug's Volume of Distribution (VD) measures how widely a drug is distributed in body tissue. VD relates directly to the amount of drug distributed into the tissue; a higher VD indicates a greater amount of tissue distribution.

  • Question of

    A pharmacokinetic measure of the volume of plasma from which a substance is completely excreted in a unit of time.

    • Clearance
    • Loading dose
    • Potency
    • Absorption

    Correct Wrong

    Clearance is a pharmacokinetic measure of the volume of plasma from which a substance is completely excreted in a unit of time. Clearance is usually measured in L/h or mL/min. Clearance is determined by dividing the rate at which a drug is removed from plasma (mg/min) by its concentration in plasma (mg/mL).

  • Question of

    Commonly used to assess the extent of exposure of a drug.

    • Under the curve
    • Therapeutic index
    • Loading dose
    • Pharmacodynamics

    Correct Wrong

    To determine the extent of a drug's exposure, the area under the curve (AUC) is commonly used. AUC can be used to determine if two formulations of a given dose (for example, a capsule versus a tablet) result in an equal amount of exposure to the tissues or plasma.

  • Question of

    The length of time for the concentration of a drug to decrease to half in the body.

    • Half-life
    • Chirality
    • Potency
    • Under the curve

    Correct Wrong

    The half-life of a substance (usually a drug) refers to the amount of time it takes for its concentration in the body to decrease to half. (Image shows: Bicalutamide's mean elimination half-life was 5.5 to 6.3 days in this study.)

  • Question of

    This is a measure of the rate and extent to which a drug reaches its target.

    • Bioavailability
    • Median effective dose
    • Volume of distribution
    • Clearance

    Correct Wrong

    Whenever a medication is administered intravenously, its bioavailability is 100%. The bioavailability of a medication administered via routes other than intravenous is generally lower than its bioavailability through intestinal endothelial absorption and first-pass metabolism.

  • Question of

    An occurrence in which a drug is metabolized in a particular location within the body, resulting in a decreased concentration of the active ingredient once it reaches its target site or enters the circulation system.

    • First pass effect
    • Downregulation
    • Adverse drug reaction
    • Median effective dose

    Correct Wrong

    The first pass effect is an occurrence in which a drug is metabolized in a particular location within the body, resulting in a decreased concentration of the active ingredient once it reaches its target site or enters the circulation system.

  • Question of

    Describes the journey of a drug traveling from the site of administration to the site of action.

    • Absorption
    • Therapeutic index
    • Loading dose
    • Clearance

    Correct Wrong

    Absorption refers to the journey of a drug from the site of administration to the site of action. There are several steps involved in describing absorption. A drug's chemical composition, as well as the environment in which it is placed, influence its absorption rate and extent.