Applied Pharmacology for the Dental
Hygienist-Chapter 2: Drug Action &
Handling updated 2026
• What terms are used to measure drug response or action? -✓✓Dose-Response
Curve, Potency & Efficacy.
• What is a Dose-Response Curve? -✓✓The measure of the response to the dose of a
drug given, when a drug exerts an effect on Biologic Systems. (If you plot the dose of
the drug against the intensity of the effect, this curve will result.)
• How can the Potency & Efficacy of a drug's action be determined? -✓✓If the above
curve is replotted using the log of the dose or Log Dose VS the Response.
• What is the Potency of a drug? -✓✓The amount of drug required to produce an effect.
• Example of Potency: -✓✓Meperidine & Morphine have the ability to treat severe pain
BUT 100 mg of Meperidine is required to produce the same action as 10 mg of
Morphine.
• Less potent drugs require? -✓✓Higher doses to produce Therapeutic Effects, whereas
more potent drugs can reach Toxic Levels at Lower doses.
• What is Efficacy? -✓✓The maximum intensity or Effect or Response that can be
produced by a drug.
• Will administering more drug increase the efficacy of a drug? -✓✓NO, but it CAN raise
the probability of an Adverse Reaction.
• What is the Therapeutic Index or TI of a drug? -✓✓It is a ratio of the Median Lethal
Dose (LD50) to the Median Effective Dose (ED50) & is expressed as : TI=LD50/ED50.
• What does the LD 50 measure? -✓✓Bc death is the end point when measuring the
lethal dose, the LD 50 is the dose that causes death in 50% of test animals.
• What does the ED 50 measure? -✓✓It is the dose required to produce the desired
clinical effect in 50 % of test animals.
• The greater the TI, the? -✓✓Safer the drug. (Drugs w/a Lower TI (closer to 0) require
careful monitoring to avoid toxic reaction). Ex of a drug w/a Low TI: Digoxin used to
treat Heart Failure.
Hygienist-Chapter 2: Drug Action &
Handling updated 2026
• What terms are used to measure drug response or action? -✓✓Dose-Response
Curve, Potency & Efficacy.
• What is a Dose-Response Curve? -✓✓The measure of the response to the dose of a
drug given, when a drug exerts an effect on Biologic Systems. (If you plot the dose of
the drug against the intensity of the effect, this curve will result.)
• How can the Potency & Efficacy of a drug's action be determined? -✓✓If the above
curve is replotted using the log of the dose or Log Dose VS the Response.
• What is the Potency of a drug? -✓✓The amount of drug required to produce an effect.
• Example of Potency: -✓✓Meperidine & Morphine have the ability to treat severe pain
BUT 100 mg of Meperidine is required to produce the same action as 10 mg of
Morphine.
• Less potent drugs require? -✓✓Higher doses to produce Therapeutic Effects, whereas
more potent drugs can reach Toxic Levels at Lower doses.
• What is Efficacy? -✓✓The maximum intensity or Effect or Response that can be
produced by a drug.
• Will administering more drug increase the efficacy of a drug? -✓✓NO, but it CAN raise
the probability of an Adverse Reaction.
• What is the Therapeutic Index or TI of a drug? -✓✓It is a ratio of the Median Lethal
Dose (LD50) to the Median Effective Dose (ED50) & is expressed as : TI=LD50/ED50.
• What does the LD 50 measure? -✓✓Bc death is the end point when measuring the
lethal dose, the LD 50 is the dose that causes death in 50% of test animals.
• What does the ED 50 measure? -✓✓It is the dose required to produce the desired
clinical effect in 50 % of test animals.
• The greater the TI, the? -✓✓Safer the drug. (Drugs w/a Lower TI (closer to 0) require
careful monitoring to avoid toxic reaction). Ex of a drug w/a Low TI: Digoxin used to
treat Heart Failure.
