Excretion

Question 1

What is the definition of renal clearance?

Answer 1

the volume of plasma that is freed of the substance (drug) per unit of time

Question 2

How do you calculate the renal clearance?

Answer 2

Clr = excretion rate of drug/ [Drug]plasma

= [Drug]urine x F/ [Drug]plasma

Question 3

What is GFR determined by?

Answer 3

1. PAH- the worst way to determine GFR- not accurate
2. Creatinine - endogenous product is secreted so it will over estimate the GFR
3. Inulin is a naturally occurring polysaccharide. MW of 5000 so it is filtered by the glomerulus and is not secreted and not reabsorbed. This gives a good idea of the GFR and is the most accurate

Question 4

In the glomerulus, there is _____ of water being filtered, and there is a lot of water being reabsorbed

Answer 4

130 ml/min (this is the GFR)

Question 5

How can you increase the plasma concentration of the drug?

Answer 5

you can do this by blocking the transporter - probenecid is what blocks the transporter

Question 6

What occurs when the renal clearance is the same as the GFR?

Answer 6

there is filtration occurring, but nothing is being secreted or absorbed

Question 7

What occurs when the renal clearance is much higher than the GFR?

Answer 7

The compound will be both filtered and secreted

Question 8

What occurs when the renal clearance is much lower than the GFR?

Answer 8

it fill be filtered, and will probably be reabsorbed

Question 9

What generally happens when the clearance rate of the dug is much larger than the bile flow rate itself?

Answer 9

the drug is being secreted- it also uses an ABC transporter that uses energy
- you know that the bile is being actively pumped into the bile cannicula

Question 10

When the MW of the drug is under 300, it is being excreted in the _____

Answer 10

urine

Question 11

When the MW of the drug is over 300, it is being excreted in the ____

Answer 11

bile

Question 12

What is the general rate of bile flow?

Answer 12

05-0.8 ml/min

Question 13

What can the biliary clearance rate reach up to?

Answer 13

500 ml/min

Question 14

Why are the microbes in the small intestine important to metabolism?

Answer 14

In the small intestine, there are microbes that are very important to metabolism - allows the drug to get into enterohepatic circulation and eventually be glucuronidated by the liver

Question 15

What is an example of medication that goes through enterohepatic recirculation and what are the implications of this?

Answer 15

• it is important in BC pills - it allows the concentration of the drug to be low (decreases the risk of SE) because we rely on enterohepatic circulation to deglucuronate medications

Question 16

Why are there potential problems when on antibiotics and killing off the intestinal bacteria?

Answer 16

• the antibiotics are killing off the intestinal bacteria
• this is an issue because we rely on the intestinal bacteria to deglucuronate the BC pills - this causes the person to excrete the medication unmetabolized in the feces

Question 17

What is the whole process of enterohepatic circulation?

Answer 17

tablet ->
small intestine  ->
superior mesenteric vein ->
portal vein ->
liver ->
(this is where glucuronidation occurs) -> excreted into the common bile duct and out as feces

Question 18

What are some other examples of drugs excreted in the bile?

Answer 18

morphine
digoxin
bile acids
steroids

Question 19

What is the definition of equivalence?

Answer 19

compares one drug product to another

Question 20

What is the definition of pharmaceutical equivalents?

Answer 20

drug products that contain the same active drug ingredients and are identical in strength or concentration, dosage form and route of administration

Question 21

What is considered a pharmaceutical alternatives?

Answer 21

drug products that contain the same therapeutic moiety but as different salts, esters or complexes

Question 22

What is considered a bioequivalent drug product?

Answer 22

are pharmaceutical equivalents that have similar bioavailability when given in the same molar dose and studied using similar experimental conditions