Pharmacokinetics 2

Question 1

What are the two methods of elimination

Answer 1

Biotransformation

Excretion

Question 2

Biotransformation

Answer 2

alterations to a drug to turn it into a metabolite which is usually inactive or reduced level of pharmacological activity

fast process

Question 3

What are the different methods for biotransformation and what is their ultimate goal

Answer 3

• oxidation; add oxygen or remove hydrogen (predominate method), done by DMMS PHASE 1
• reduction; remove oxygen or ass hydrogen PHASE 1
• hydrolysis; original compound it broken into two parts PHASE 1
• conjugation; substance is coupled to an endogenous substance PHASE 2

makes the compound more polar, becoming ionized in the body’s fluids (more water soluble) and therefore more easily transported into bloodstream and to the kidneys where it can be excreted

Question 4

What is the primary location for drug metabolism

Answer 4

liver

Question 5

Enzyme induction

Answer 5

prolonged use of certain drugs induces the body to adjust and enzymatically destroy more rapidly than expected

usually bc more metabolizing enzymes are being made or fewer are being degraded

induction decreases the drugs effect and leads to tolerance

Question 6

Tolerance

Answer 6

the need for increased drug dosage to produce the same effect

Question 7

Primary site of drug excretion and other routes

Answer 7

kidneys - nephron

lungs, GI, liver to bile, breast milk, sweat and saliva

Question 8

How does the kidney perform excretion

Answer 8

traps water soluble (ionized) compounds for elimination via urine

Question 9

What determines the amount and frequency of drug dosage

Answer 9

Drug elimination rates

• if drug is administered faster than its eliminated then there will be excessive accumulation and possibly toxic levels
• if a drug is eliminated faster than administration it will not reach therapeutic levels

Question 10

Clearance (CL)

Answer 10

For a single organ or tissue, CL depends on the organs ability to extract the drug from the plasma and the perfusion of the organ

CL rate = Q (blood flow to the organ) X (Ci - Co) / Ci

Ci = amount of drug entering organ
Co = amount leaving the organ

Question 11

Systemic Clearance

Answer 11

the sum of all organs and tissues abilities to eliminate the drug

Question 12

Half - life

Answer 12

the amount of time for 50% of the drug remaining in the body to be eliminated

Question 13

What two concepts effect half life

Answer 13

Clearance and Volume of distribution

Question 14

Dosing schedules and plasma concentration

Answer 14

Larger doses are given farther apart result in greater plasma fluctuations vs something like a constant IV infusion

Question 15

What factors cause variations in the response to drugs and their metabolism?

Answer 15

• Genetics
• Disease (damage to tissue ot organ responsible for drug metabolism or excretion)
• Drug Interactions
• Age
• Diet

_ Gender

• Exercise, smoking, alcohol, burn injuries