Pharmacology and Pharmacokinetics

Question 1

What is a Drug Receptor?

Answer 1

A portion of tissue or cell to which a drug can bind and initiate its effect. Receptors can cause effects if activated or blocked.

Question 2

Describe the Drug-Receptor Complex.

Answer 2

It is not static; there is a continuous association and dissociation of the drug with the receptor as long as the drug is present.

Question 3

What is Pharmacology?

Answer 3

The rational discussion or study of drugs and their interactions with the body.

Question 4

What is Pharmacodynamics?

Answer 4

The study of actions of drugs on the body, including the effect on the patient, mechanism of action, beneficial and adverse effects, and clinical application of the drug.

Question 5

What is Pharmacokinetics?

Answer 5

The study of the action of the body on drugs.

Question 6

What is Pharmacogenomics?

Answer 6

The study of how genetic makeup affects pharmacodynamics and pharmacokinetics, influencing drug selection and application. Examples include cancer treatment and HIV medication screening.

Question 7

What is Drug Nomenclature?

Answer 7

It includes:
a. Chemical Name: Based on chemical and molecular constituents.

b. Generic Name: Assigned by the manufacturer, used commonly after approval (e.g., Acetaminophen).

c. Trade/Brand Name: Assigned by the manufacturer, used commercially and can vary after patent expiration (e.g., Tylenol).

Question 8

What is the Fundamental Principle of Pharmacology?

Answer 8

Drugs must interact with a molecular target to exert an effect, initiating a multistep process that alters tissue function with intended and unintended effects.

Question 9

What is the Law of Mass Action?

Answer 9

Interaction of drugs and receptors follows the law of mass action, where drug-receptor complex formation depends on the concentration of each. Saturation occurs when all receptors are bound.

Question 10

Define Drug Binding Affinity.

Answer 10

Affinity refers to the strength with which a drug forms a complex with its receptor. Factors include the size and shape of the drug molecule, binding site characteristics, and intermolecular forces.

Question 11

What is Selectivity of Drug Response?

Answer 11

It is determined by a drug’s preferential affinity for specific receptors, affecting its action and potential side effects. Drugs with higher selectivity have fewer side effects.

Question 12

What are Agonists and Antagonists?

Answer 12

a. Agonists activate cell receptors and induce responses similar to natural substances (e.g., bronchodilators).

b. Antagonists block the effects of natural substances at receptors (e.g., antihistamines).

Question 13

What is Antagonism as a Mechanism of Action?

Answer 13

Antagonists block receptor actions without changing the receptor itself. Types include chemical antagonists, physiologic antagonists, and examples like epinephrine and histamine.

Question 14

Describe Dose-Response Relationships.

Answer 14

a. Graded: Response to varying doses in individuals (e.g., alcohol).

b. Quantal: All or none responses (e.g., seizure prevention with Lamotrigine).

Question 15

What is ED-50?

Answer 15

The dose at which 50% of the test subjects show a predefined or expected effect. Used to set recommended doses.

Question 16

What is LD-50?

Answer 16

The estimated dose at which 50% of subjects would die from drug intake, typically derived from animal studies.

Question 17

What is TD-50?

Answer 17

The dose that will produce toxicity in 50% of animals tested, often used for estimating safety.

Question 18

What is the Therapeutic Index (TI)?

Answer 18

The ratio between the LD-50 and ED-50. A high TI indicates a wider safety margin between effective and toxic doses.

Question 19

What is Tachyphylaxis?

Answer 19

Rapid reduction in drug responsiveness due to repetitive administration, resulting in acute loss of sensitivity.

Question 20

What is Tolerance?

Answer 20

Gradual reduction in drug responsiveness over time due to prolonged drug administration.

Question 21

What are Drug Formulations?

Answer 21

Includes solid (tablets, capsules), semisolid (creams, ointments), liquid (suspensions, solutions), and polymer-based formulations for controlled release.

Question 22

What is Absorption in pharmacokinetics?

Answer 22

The amount of drug reaching the general circulation from its site of administration. Influenced by factors like blood flow, surface area, solubility, and pH.

Question 23

What are Routes of Administration?

Answer 23

Include enteral (PO, rectal, sublingual).

Parenteral (IV, IM, SC, transdermal)

Other methods (inhalational, intranasal, topical, intrathecal).

Question 24

Describe the PO (oral) route

Answer 24

1. Bioavailability of PO drugs vary greatly.
2. Drugs given orally must be acid stable.
3. Gastric emptying time, intestinal motility, food, intestinal metabolism and transport, and hepatic metabolism all influence absorption of oral medications.

Question 25

Describe the Rectal route

Answer 25

1. Produces systemic effect.
2. Advantageous for drugs with low bioavailability because ~50% of drug bypasses portal circulation.
3. Also useful for local, topical effects.

Question 26

Describe the Sublingual/Buccal route

Answer 26

1. Advantageous for drugs with low bioavailability as venous drainage from the mouth bypasses the liver
2. Absorbed rapidly; Drugs must be lipophilic.

Question 27

Describe the IV route

Answer 27

Bioavailability of drug is 100%; most reliable.

Question 28

Describe the IM route

Answer 28

Dependent on muscle blood flow.

Question 29

Describe the SC route

Answer 29

Used for drugs with low bioavailability; not appropriate for tissue irritant solutions as they may produce necrosis.

Question 30

Describe the Transdermal route

Answer 30

Slow absorption but produces long lasting effects; drugs must be lipophilic.

Question 31

Describe the Inhalational route

Answer 31

Absorption is rapid and complete. Drugs must be gaseous or fine aerosols. Effects can be local or systemic.

Question 32

Describe the Intranasal route

Answer 32

Absorbed through the mucous membranes in the nasal passage and then into the bloodstream.

Question 33

Describe the Topical route

Answer 33

Less lipophilic to reduce systemic absorption.

Question 34

Describe the Intrathecal route

Answer 34

Penetrates subarachnoid space to allow access to the CSF (cerebrospinal fluid).

Question 35

What is Plasma Protein Binding?

Answer 35

Refers to how drugs bind to plasma proteins, which affects the amount of free drug available for action. Changes in binding can impact drug efficacy and safety.

Question 36

What are the two basic means of Drug Elimination?

Answer 36

Metabolism and excretion.

Question 37

What is Drug Metabolism?

Answer 37

The biochemical alteration of drugs in the body, primarily occurring in the liver, involving enzymes like cytochrome P450.

Question 38

What is Drug Excretion?

Answer 38

The removal of drugs from the body, including through the kidneys, bile, sweat, breast milk, and lungs.

Question 39

What is Clinical Pharmacokinetics?

Answer 39

The study of drug behavior in the body to maximize beneficial effects while minimizing adverse effects, understanding dosages, intervals, and drug actions.

Question 40

What is Half-Life (t ½)?

Answer 40

The time required for half of a drug to be eliminated from the bloodstream. It helps in determining dosing intervals and understanding drug clearance.

Question 41

What are Administration Protocols?

Answer 41

a. Continuous administration achieves steady-state drug concentrations.

b. Intermittent administration leads to fluctuating drug levels.

c. Loading doses are used for rapid drug effect, particularly in emergencies.