Lecture 6 review

Question 1

The four processes of pharmacokinetics

Answer 1

ADME
Absorption
Distribution
Metabolism
Excretion

Question 2

Minimum effective concentration (MEC)

Answer 2

Below this level, there will be no therapeutic effects

Question 3

The wider the band is between the MEC and toxic concentration _______

Answer 3

The easier and safer the drug is to administer

Question 4

What is the drug’s half life used for?

Answer 4

The half-life is used to determine the dosing interval so the duration of action of the drug is maintained

Question 5

General rule for half-lives

Answer 5

It takes 4 half-lives for a drug to reach steady state in the plasma and similarly it takes 4 half-lives for a drug to be eliminated from the body

Question 6

Drugs can only produce therapeutic effects….

Answer 6

That are already physiologic activities normally regulated by the endogenous receptors

Question 7

How do drugs produce their effects?

Answer 7

By primarily binding with receptors in the body. When a drug binds to its target receptor, the physiologic activity controlled by that receptor can either be increased or decreased

Question 8

What are the four families of receptors that drugs act on?

Answer 8

1) cell membrane-embedded enzymes
2) ligand-gated ion channels
3) G protein-coupled receptor systems
4) transcription factors

Question 9

Cell membrane-embedded enzymes

Answer 9

When a drug binds to these receptors, the enzymes is activated and increased catalytic activity within seconds

Question 10

Ligand-gated ion channels

Answer 10

When a drug binds to these receptors on the cell membrane, the flow of ions in and out of cells is regulated. This occurs rapidly, in milliseconds

Question 11

Transcription factors

Answer 11

These receptors are located on the DNA of the cell nucleus. When activated by a drug, messenger RNA is transcribed and specific proteins are synthesized. There is a delay in this response

Question 12

How can drugs affect receptors?

Answer 12

1. agonists
2. antagonists
3. Partial agonists

Question 13

Agonists

Answer 13

By activating or mimicking the receptor’s activity

Question 14

Antagonists

Answer 14

By preventing the receptor from being activated by an endogenous regulatory molecules or drugs.

Question 15

Requirement for an antagonist drug to have any effect

Answer 15

For an antagonist drug to have any effect at the receptor site, there must be some agonist molecules present or nothing will happen

Question 16

Partial agonists

Answer 16

By partially activating the receptor for modest effect. They are used to produce modest effects and to minimize adverse effects that can result from full activation of the receptor

Question 17

Maximal efficacy

Answer 17

The biggest effect a drug can produce. The goal of drug therapy is to match the drug’s maximal efficacy with the intensity of the patient’s needs.

Question 18

Potency

Answer 18

The amount (dose) of a drug needed to produce an effect. A potent drug is one that produces the desired effect at a lower dose.

Question 19

The average effective dose (ED50)

Answer 19

Defined as the dose required to produce a defined therapeutic response in 50% of the population. This means that this dose will be too low or too high for the other 50% of the population

Question 20

The LD50, or average lethal dose

Answer 20

The dose that is lethal to 50% of the animals treated in a lab

Question 21

The therapeutic index

Answer 21

A measure of a drug’s safety. TI = LD50/ ED50. The closer this number is to zero, the more unsafe the drug.

Question 22

Drug-drug interactions

Answer 22

When two or more drugs interact, the result can be 1) intensified affects, 2) diminished effects or 3) a new effect which could be detrimental or beneficial

Question 23

Drug-food interactions

Answer 23

Food may affect the rate or extent of absorption of drugs taken orally. Some foods can inhibit the metabolism of certain drugs and others may increase the toxicity of the drug

Question 24

Direct chemical or physical interactions

Answer 24

Occur when two incompatible drugs are mixed together or combined in a solution such as in an IV solution. Often (but not always) produces a visible precipitate, clumping, or clouding of the solution

Question 25

Pharmacokinetic interactions

Answer 25

When one drug causes alterations in absorption, distribution, metabolism or renal excretion, it can impact the effect of other drugs

Question 26

Anti-histamines could result in……

Answer 26

anti-cholinergic side effects

Question 27

Anti-cholinergic side effects

Answer 27

“Blind as a bat (mydriasis), mad as a hatter (delirium), red as a beet (flushing), hot as a hare (hyperthermia), dry as a bone (decreased secretions and dry skin), the bowel and bladder lose their tone (urinary retention and paralytic ileus), and the heart runs alone (tachycardia)”

Question 28

Drugs to avoid/ use with caution in older adults

Answer 28

• Non-selective NSAIDs
• tri-cyclic anti-depressants
• first generation anti-histamines
• Benzodiazepines
• proton-pump inhibitors
• alpha blockers/ agonists