Pharmacodynamics

Question 1

What are the 9 ideal drug properties?

Answer 1

1) Convenient route of administration, probably taken by mouth
2) Established dosage
3) Immediate onset of action
4) Produces a single desired biological action
5) Produces no unwanted effects
6) Convenient duration of action
7) Dosage unaffected by loss of kidney or liver function or by disease state
8) Improves quality of life
9) Prolongs patient survival

Question 2

What are the stages of drug development?

Answer 2

1) Preclinical phase
2) Clinical stage
3) Post-marketing surveillance

Question 3

What happens in the preclinical stage?

Answer 3

Identification of promising drugs and their testing in animals. Preclinical studies are performed on cells, isolated tissues and organs, and in laboratory animals to identify promising compounds.

Question 4

What happens during the clinical trials of new drugs?

Answer 4

Pharmaceutical companies must establish the safety and effectiveness of new products in humans.

Phase I clinical trials typically establish biological effects as well as safe dosages and pharmacokinetics in a small number of healthy patients.

In phase II, new drugs are tested in a small number of humans with a disease.

In phase III, the new drug is compared to similar drugs in a larger number of patients across the country.

Question 5

What is evaluated during the post-surveillance phase?

Answer 5

Adverse side effects and pharmacogenomics are studied.

Question 6

What is pharmacogenomics?

Answer 6

Pharmacogenomics is the study of how individual variations in drug targets or metabolism affect drug therapy.

Question 7

What is homeostasis?

Answer 7

The tendency of a cell, tissue, or the body not to respond to drugs but instead to maintain the internal environment by adjusting physiological processes.

Question 8

What are two basic types of drug responses?

Answer 8

Quantum and Graded

Question 9

What are graded responses?

Answer 9

Graded responses are biological effects that can be measured continually up to the maximum responding capacity of the biological system. Most drug responses are graded.

Question 10

What are quantal responses?

Answer 10

Quantal effects are responses that may or may not occur. For example, seizures either occur or they do not, as in pregnancy, sleep, and death.

Some other quantal responses such as seizures, you can count the number of occurrences. This can be helpful in adjusting medications to improve patient response with fewer or shorter seizures (a graded response), even though the goal is a seizure-free (quantal response) patient.

Question 11

Drug Responses

Answer 11

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Question 12

What is drug selectivity?

Answer 12

A ratio of the dose or concentration producing the undesired effect to the dose or concentration producing the desired effect. This is the same as determining how many times the therapeutic dosage needs to be increased to produce the undesired effect.

A medication that requires one tablet to produce the desired response and does not produce undesirable effects unless five tablets are used would have a selectivity ratio of 5.

Question 13

What is the therapeutic index?

Answer 13

A special ratio describing drug selectivity. The therapeutic index is the ratio of the lethal dose of a drug to the therapeutic dose of a drug. It uses death, a really unacceptable adverse effect, and it uses data from animal studies.

Question 14

What does a therapeutic index of less than 1 mean?

Answer 14

A therapeutic index of less than 1 means that the drug kills before it cures.

Question 15

What are the types of receptors drugs bind to?

Answer 15

1) Ion channel
2) G-proteins
3) Transmembrane Receptors
4) Intracellular Receptors Regulating Gene Expression
5) Enzymes
6) Drug Action at Receptors
7) Non-receptor Mechanisms

Question 16

How do ion channel receptors work?

Answer 16

• transmit signals across the cell membrane by increasing the flow of ions and altering the electrical potential
• Activated nicotinic receptors are responsible for muscle contraction.
• Nicotinic receptor consists of five subunits forming a cylindrical structure with a hole in the center.
• Acetylcholine (ACh) binds to the two alpha subunits, opening the central channel, permitting sodium to enter and potassium to leave the cell

Question 17

What are examples of ion channel receptors?

Answer 17

Ion channel receptors include receptors for ACh (nicotinic), gamma-aminobutyric acid (GABA), and excitatory amino acids (glycine, aspartate, glutamate, etc.).

Question 18

work how do G protein receptors work?

Answer 18

• Seven regions of protein span the cell membrane to create a pocket (in which drugs can bind) and end with a receptor “tail” inside the cell
• Receptors are activated when specific drugs interact with the binding site, producing a conformational change, a sort of twist, in the G protein
• Activation of receptors then produces intracellular changes in the binding of the G-protein receptor to second messengers

Question 19

What are second messengers?

Answer 19

Proteins that control response through other molecules.

Second messengers include molecules such as cAMP (cyclic adenosine monophosphate), Ca ++, phosphoinositides, and diacylglycerols.

Question 20

What is phosphorylation?

Answer 20

Placing a phosphate group on a protein, is a way of marking it for activation or inactivation.

Question 21

What are the three major subunits of G proteins?

Answer 21

G proteins are made up of three major subunits alpha [α], beta [β], and gamma [γ].

Question 22

Transmembrane Receptors

Answer 22

• Extracellular hormone-binding domain
• Intracellular enzyme domain that phosphorylates the amino acid tyrosine.

The protein tyrosine kinase includes receptors for insulin, epidermal growth factor, and platelet-derived growth factor.