Class 3 - Pharmacology

Question 1

What are the 4 processes of pharmacominetics?

Answer 1

1 . Absorption
2. Distribution
3. Metabolism
4. Excretion

Question 2

Absorption

Answer 2

The movement of a drug from the site of administration to the blood

Question 3

Distribution

Answer 3

• Movement of the drug from the blood to interstitial space of tissues and enter the cell
• It is determined by 3 major factors: blood flow to tissues, the ability of a drug to exit the vascular system, and the ability of a drug to enter cells

Question 4

Metabolism

Answer 4

• To be excreted by kidneys
• Some drugs act on specific liver enzymes to increase rate of metabolism (inducers) –> the plasma levels fall and its therapeutic effect is reduced
• Others decrease metabolism (inhibitors) -> when metabolization is inhibited, drug plasma levels stay high, increasing the effect of the drug… toxicity

Question 5

First pass effect

Answer 5

When drugs are absorbed from the GI tract and immediately pass through the liver resulting in significant inactivation of the drug and limiting its therapeutic effect

Question 6

What are the 6 possible consequences of drug metabolism

Answer 6

1. Accelerated excretion from the kidneys
2. Inactivation of the drug
3. Conversion of a “prodrug” to its active form
4. Increased therapeutic action
5. Increased toxicity
6. Decreased toxicity

Question 7

Excretion

Answer 7

• The kidneys excrete the majority of drug
• Drugs can also be excreted through secretion in bile and then excreted in the feces, through the lungs, and in the sweat glands, saliva and breast milk

Question 8

Ionization rule

Answer 8

• Nonionized drugs = lipid soluble –> absorbed (can cross BBB)
• Ionized drugs = water soluble –> excreted (travel through pores in capillaries)

Question 9

Protein binding in drugs

Answer 9

ALBUMIN
- All drugs have this property
- Reversible
- A drug that is highly protein bound may take longer to develop a plasma concentration

Question 10

Half-life

Answer 10

The time required for the plasma level of the drug to decrease by 50% after administration
- Determines the dosing interval

Question 11

How many half-lives to hit therapeutic range?

Answer 11

To hit a steady state in the plasma it takes 4 half-lives

Question 12

What are the 4 families of receptors that drugs act on

Answer 12

1. Cell membrane-embedded enzymes
2. Ligand-gated ion channels
3. G protein-coupled receptor systems
4. Transcription factors

Question 13

3 ways drugs can affect receptors

Answer 13

1. Agonist
2. Antagonist
3. Partial agonist

Question 14

Agonist

Answer 14

By activating or mimicking the receptor’s activity

Question 15

Antagonist

Answer 15

Block/prevent the action of endogenous regulatory molecules
- Non-competitive vs Competitive

Question 16

Partial anatgonist

Answer 16

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 is to match the drug’s maximal efficacy with the intensity of the patient’s needs

Question 18

Potency

Answer 18

The amount of a drug need to produce an effect

Question 19

Altered metabolism

Answer 19

CYP450 liver enzyme system
- Enzymes induced by Drug A –> Drug B effects reduced
- Enzymes inhibited by Drug A –> Drug B effect increased

Question 20

Lab values

Answer 20

• Kidney = SERUM CREATININE
  M (53-106 mcmol/L); F (44-97 mcmol/L)
  – Increased level = kidney impairment
  – Decreased level = decreased muscle mass
• Liver = LIVER FUNCTION TESTS (AST/ALT)
• Electrolytes = SODIUM AND POTASSIUM
  S (135-145 mmol/L); P (3.5-5 mmol/L)
  – Some drugs will increase levels and other drugs ill decrease levels