Pharmacokinetics

Question 1

What is pharmacokinetics?

Answer 1

Pharmacokinetics is the study of how drugs are impacted by the body

Question 2

What is absorption?

Answer 2

The movement of a drug from it’s site of administration into the blood

Question 3

What affects absorption?

Answer 3

The rate of dissolution, blood flow, surface area, lipid solubility, and pH partitioning

Question 4

How does lipid solubility affect absorption?

Answer 4

An increased lipid solubility allows for the drug to cross the cell membrane easier, thus increasing its rate of absorption

Question 5

What is rate of absorption?

Answer 5

The rate is how fast the med is absorbed and how quickly effects occur

Question 6

How does pH partitioning affect absorption?

Answer 6

Drugs favor a pH where they ionize (acid->base, base->acid), thus a pH will be more readily absorbed where their pH favors ionization

Question 7

What is distribution?

Answer 7

Distribution is the drugs movement from the blood to the interstitial space and into the cells (sites of action)

Question 8

What affects distribution?

Answer 8

Distribution is affected by blood flow and the drugs ability to exit the vasculature

Question 9

What affects the ability to exit the vasculature?

Answer 9

Lipid solubility: ability to pass through the cells membranes
Protein binding: binding to albumin and ifs affinity to the bond can prevent the drug from unbinding and getting to the site of action

Question 10

What is metabolism?

Answer 10

The chemical alteration of the drug structure to promote the degradation and eventual excretion

Question 11

Where does the majority of metabolism occur in the body?

Answer 11

The liver

Question 12

What enzymatic pathway promotes drug metabolism

Answer 12

The P450 system

Question 13

What is a prodrug?

Answer 13

A drug that needs to be metabolized and converted to it’s active form my the liver before it is effective

Question 14

What effects can metabolism have on toxicitiy?

Answer 14

Through metabolism, the liver can inactivate the drug and prevent toxicity OR it can inactivate the drug and cause it to be converted into a toxic chemical in the body

Question 15

What is a special consideration for metabolism with infants?

Answer 15

Infants have an underdeveloped liver and require lower doses due to their inability to breakdown medications

Question 16

What is a special consideration for metabolism with the elderly?

Answer 16

The elderly have a slower metabolic rate and will also need smaller doses due to the prolongation of the drug in their system

Question 17

What is the first-pass effect?

Answer 17

First-pass effect is when a drug undergoes rapid hepatic inactivation during the first pass through the liver. It can render drugs inactive and ineffective prior to getting to the site of action. This is accounted for in dosing of medications from FDA approval and research.

Question 18

How does nutrition affect metabolism?

Answer 18

Malnutrition can cause alterations in cofactors of metabolism

Question 19

What is excretion?

Answer 19

Excretion is the body’s elimination process of the drug

Question 20

Where are the 2 primary sites for excretion?

Answer 20

The kidneys through the urine and the GI tract through bile and feces

Question 21

What is a concern with excretion of a drug through the bile?

Answer 21

Enterohepatic recirculation where the medication can be reabsorbed through the GI tract and undergo metabolism again, can increase levels in the body and promote toxicity

Question 22

What is passive reabsorption?

Answer 22

Drugs travel from the urine back into the blood stream due to lipid solubility or pH ionization