Pharmacology Exam 1
(Questions with Open
Answers)
1. Differentiate between therapeutic effect, side effect, and toxic effect. - Correct answer
Therapeutic effect is the reason for administering a drug, to alleviate some symptom or disease
process. A side effect is an additional fact, unwanted but usually not harmful. Drowsiness after
some cold remedies is an example of a side effect. A toxic effect is a harmful effect that requires a
reduction in dosage or elimination of the drug.
2. What is the difference between site of action and mechanism of action? - Correct answer Site of
action is the location within the body where a drug exerts its therapeutic effect. It may be a body
organ, tissue, or specific drug receptor site. The mechanism of action refers to how the drug
produces its effects. Mechanism of action may involve inhibition of a body enzyme or chemical
process or may involve the drug acting as an antagonist on a receptor to block the action of a
hormone or body substance.
3. What is the relationship between ED50, LD50, and therapeutic index? - Correct answer The
effective dose 50 (ED50) is the dose that will produce half the maximal response possible. The
lethal dose 50 (LD50) is the dose that will kill half of the animals tested during a test of drug
toxicity. The therapeutic index is the ratio of the ED 50 to the LD 50, which provides an estimate of
the relative safety of a drug.
4. Explain the difference between a prescription drug, OTC drug, and a controlled substance. -
Correct answer Prescription drugs require a written or phone order by a licensed physician and
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,must be dispensed by a licensed pharmacist. OTC drugs can be sold at a variety of stores and do
not require a physician or pharmacist. Controlled substances are drugs that have the potential for
abuse and are scheduled and regulated by the Drug Enforcement Administration (DEA).
5. Explain the difference between idiosyncrasy and drug allergy. - Correct answer Idiosyncrasy is
an unusual or unexpected drug response. It is usually caused by genetic differences among
individuals.
Drug allergy is an adverse drug reaction that occurs when an individual becomes sensitized to a
drug. Antibodies produced within the body react with the drug to cause an allergic reaction
6. Write a short paragraph describing the terms agonist, antagonist, competitive antagonism,
noncompetitive antagonism, and uncompetitive antagonism, reverse agonist, partial agonist -
Correct answer Agonists stimulate the activation of receptors, while antagonists suppress the
activity of receptors, antagonist have no effect without agonist.
When an agonist drug and an antagonist drug bind specifically to the same site of the receptors,
they are referred to as competitive antagonists. If they are both administered at the same time,
they compete with each other for binding to the receptors; this is known as competitive
antagonism.
Noncompetitive does not bind the same site as the nature ligand and it allosteric affects the
efficacy the natural ligand.
Uncompetitive antagonist requires the prior activation of receptor and affects both the potency
and efficacy of natural ligand.
7. What is the main disadvantage to the IV method of drug administration? - Correct answer Once
a drug is injected, it cannot be withdrawn. Miscalculation of dosage or mistakes in drug selection
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, may cause serious consequences. Intravenous injection also requires the services of medical
personnel to administer the drug. It has the risk of infection. Pain.
8. By what method of cell transport are most drugs absorbed? What are the main requirements for
drug absorption? - Correct answer Drugs are primarily absorbed by passive diffusion. Drugs
possessing lipid solubility are readily absorbed. If a drug is water soluble or ionizable, the un-
ionized form is required for absorption to occur. The degree of ionization of the drug and the pH of
the solution determine the proportion of ionized and un-ionized molecules.
9. Explain why alkalinization of the urine increases the rate of excretion of drugs such as aspirin or
phenobarbital (both are weak acids). - Correct answer Aspirin, phenobarbital, and other acidic
drugs are predominantly in their ionized form in alkaline urine and therefore are readily excreted.
In acidic urine, they are more un-ionized and consequently more likely to be reabsorbed into the
blood.
10. Briefly describe the main factors that determine drug distribution. - Correct answer The main
factors that determine drug distribution to any tissue or organ are the amount of blood normally
flowing to that organ, the degree of plasma protein binding, and the lipid solubility of the drug.
Generally, the more lipid soluble the drug, the greater the degree of distribution, especially into the
brain, adipose tissue, and other tissues with high lipid content.
11. What is the drug microsomal metabolizing system, and what is its main function? - Correct
answer The drug microsomal metabolizing system is a group of enzymes mainly in the liver that
break down lipid-soluble drugs into water-soluble metabolites. The majority of oxidases are heme
protein monooxygenases of the cytochrome P450 class. Cytochrome P450 enzymes (sometimes
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(Questions with Open
Answers)
1. Differentiate between therapeutic effect, side effect, and toxic effect. - Correct answer
Therapeutic effect is the reason for administering a drug, to alleviate some symptom or disease
process. A side effect is an additional fact, unwanted but usually not harmful. Drowsiness after
some cold remedies is an example of a side effect. A toxic effect is a harmful effect that requires a
reduction in dosage or elimination of the drug.
2. What is the difference between site of action and mechanism of action? - Correct answer Site of
action is the location within the body where a drug exerts its therapeutic effect. It may be a body
organ, tissue, or specific drug receptor site. The mechanism of action refers to how the drug
produces its effects. Mechanism of action may involve inhibition of a body enzyme or chemical
process or may involve the drug acting as an antagonist on a receptor to block the action of a
hormone or body substance.
3. What is the relationship between ED50, LD50, and therapeutic index? - Correct answer The
effective dose 50 (ED50) is the dose that will produce half the maximal response possible. The
lethal dose 50 (LD50) is the dose that will kill half of the animals tested during a test of drug
toxicity. The therapeutic index is the ratio of the ED 50 to the LD 50, which provides an estimate of
the relative safety of a drug.
4. Explain the difference between a prescription drug, OTC drug, and a controlled substance. -
Correct answer Prescription drugs require a written or phone order by a licensed physician and
P a g e 1 | 24
,must be dispensed by a licensed pharmacist. OTC drugs can be sold at a variety of stores and do
not require a physician or pharmacist. Controlled substances are drugs that have the potential for
abuse and are scheduled and regulated by the Drug Enforcement Administration (DEA).
5. Explain the difference between idiosyncrasy and drug allergy. - Correct answer Idiosyncrasy is
an unusual or unexpected drug response. It is usually caused by genetic differences among
individuals.
Drug allergy is an adverse drug reaction that occurs when an individual becomes sensitized to a
drug. Antibodies produced within the body react with the drug to cause an allergic reaction
6. Write a short paragraph describing the terms agonist, antagonist, competitive antagonism,
noncompetitive antagonism, and uncompetitive antagonism, reverse agonist, partial agonist -
Correct answer Agonists stimulate the activation of receptors, while antagonists suppress the
activity of receptors, antagonist have no effect without agonist.
When an agonist drug and an antagonist drug bind specifically to the same site of the receptors,
they are referred to as competitive antagonists. If they are both administered at the same time,
they compete with each other for binding to the receptors; this is known as competitive
antagonism.
Noncompetitive does not bind the same site as the nature ligand and it allosteric affects the
efficacy the natural ligand.
Uncompetitive antagonist requires the prior activation of receptor and affects both the potency
and efficacy of natural ligand.
7. What is the main disadvantage to the IV method of drug administration? - Correct answer Once
a drug is injected, it cannot be withdrawn. Miscalculation of dosage or mistakes in drug selection
P a g e 2 | 24
, may cause serious consequences. Intravenous injection also requires the services of medical
personnel to administer the drug. It has the risk of infection. Pain.
8. By what method of cell transport are most drugs absorbed? What are the main requirements for
drug absorption? - Correct answer Drugs are primarily absorbed by passive diffusion. Drugs
possessing lipid solubility are readily absorbed. If a drug is water soluble or ionizable, the un-
ionized form is required for absorption to occur. The degree of ionization of the drug and the pH of
the solution determine the proportion of ionized and un-ionized molecules.
9. Explain why alkalinization of the urine increases the rate of excretion of drugs such as aspirin or
phenobarbital (both are weak acids). - Correct answer Aspirin, phenobarbital, and other acidic
drugs are predominantly in their ionized form in alkaline urine and therefore are readily excreted.
In acidic urine, they are more un-ionized and consequently more likely to be reabsorbed into the
blood.
10. Briefly describe the main factors that determine drug distribution. - Correct answer The main
factors that determine drug distribution to any tissue or organ are the amount of blood normally
flowing to that organ, the degree of plasma protein binding, and the lipid solubility of the drug.
Generally, the more lipid soluble the drug, the greater the degree of distribution, especially into the
brain, adipose tissue, and other tissues with high lipid content.
11. What is the drug microsomal metabolizing system, and what is its main function? - Correct
answer The drug microsomal metabolizing system is a group of enzymes mainly in the liver that
break down lipid-soluble drugs into water-soluble metabolites. The majority of oxidases are heme
protein monooxygenases of the cytochrome P450 class. Cytochrome P450 enzymes (sometimes
P a g e 3 | 24
