Issar - Drug Excretion

Question 1

What is the major organ of drug excretion

Answer 1

kidney

Question 2

The functional unit of the kidney is the ____ and includes the BC, _____, LOH, distal tubule, and _____

Answer 2

nephron; proximal tubule

Question 3

Low molecular weight molecules are filtered in ____ _____. Active secretion of weak electrolyte drugs and reabsorption of water occurs in the ______ tubules. Additional reaborption of water occurs in the ____ . Passive reabsorption of water and lipid soluble drugs occurs in the ___ ____.

Answer 3

bowmans capsule;
proximal tubule;
LOH;
distal tubule

Question 4

What are the three major renal excretion processes

Answer 4

1. Glomerular filtration
2. Active tubular secretion
3. tubular reabsorption

Question 5

Renal excretion = _____ - reabsorption + ______

Answer 5

filtration; secretion

Question 6

What is normal GFR? how much of drug gets filtered, what about reabsorbed?

Answer 6

110- 130 ml/min; 10%; 90%

Question 7

____ clearance is is equal to the glomerular _____ rate bc inulin gets filtered only.

Answer 7

inulin; filtration

Question 8

What is renal clearance?

Answer 8

CLR, is the volume of plasma from which all the substance is removed by the kidney in unit time.

Question 9

Active tubular secretion requires a ____and a supply of energy which means there could by competitive ______ of the secretion of one compound by another. This is a significant pathway for ____ . _____ competes with penicillin to be excreted.

Answer 9

carrier; inhibition; penicillin; probenecid

Question 10

_____ may have clearance values approaching the renal plasma flow rate up to 650 ml

Answer 10

PAH

Question 11

During tubular reabsorption in the distal tubules, ____ are extensilvely reabsorbed. Urine ____ plays a major role in the reabsorption of drugs. If urine pH is acidic, weak acidic drugs will get reabsorbed. But if the non ionized form of drug does not posses sufficient ___solubillity, the urinary pH will have little influence on urinary drug excretion

Answer 11

lipids; pH; lipid

Question 12

If Cldrug/Clinulin <1 then:

Answer 12

drug is being partially reabsorbed

Question 13

If Cldrug/Clinulin = 1 then:

Answer 13

drug is being filtered

Question 14

If Cldrug/Clinulin > 1 then:

Answer 14

drug is being actively secreted.

Question 15

____is used clinically to estimate the GFR in individuals and in the urine it represents a filtered component and a much smaller secreted component. Bc of the secretion, creatanine clearance is slightly higher than the ____. Plasma creatinine concentration is ____ related to GFR and is a practical indicator of how well the kidneys are filtering. So if plasma creatanine is high, creatanine clearance is LOW

Answer 15

creatinine; GFR; inversely

Question 16

Production of bile is an ____ secretion process. Active biliary secretion reported for organic ____, cations, and ___ uncharged molecules. Drugs that are excreted mainly in the bile generally have molecular weights in excess of _____. Things less than this are excreted via biliary and renal excretion

Answer 16

active; anions; polar; 500

Question 17

what is entero hepatic circulation? What enzyme helps this?

Answer 17

cycle in which is the drug is absorbed, excreted into the bile and reabsorbed; The effect of this is to create a reservoir of recirculating drug which can amt to about 20% of the drug in the body, which tends to prolong the duration of action of such drugs;
Beta glucuronidase;

Question 18

What are factors that affect biliary secretion

Answer 18

1. liver disease or injury
2. age; infants and elderly
3. chronic administration of drugs inc. bile flow
4. competition between drugs

Question 19

During pulmonary excretion, rate of drug loss is dependent on:

Answer 19

1. respiration rate
2. pulmonary blood flow
3. drug solubility

Question 20

During pulmonary excretion, to remove poor soluble drugs you need to increase ____ output. _____ soluble drugs have slow removal. Most drugs removed by lungs are not metabolized

Answer 20

cardiac; High

Question 21

Sweat and saliva have minor importance in drug excretion. You can only ____ the drug, even for IV administeered drugs

Answer 21

taste

Question 22

Drug presence in milk is dependent on:

Answer 22

1. maternal blood conc.
2. plasma protein binding
3. lipid solubility
4. pKa

Question 23

MIlk is more ___ than plasma, therefore ___ drugs accumulate. ___ soluble drugs accumulate in milk fat.

Answer 23

acidic; basic; lipid

Question 24

P-gp is needed for some drugs to be excreted and prevents toxic drugs from gaining entry in CNS. ____ and verapamil increase plasma (digoxin) by inhibiting P-gp activity. St. Johns wort decreases plasma (digoxin) by inducing Pgp activity.

Answer 24

Quinidine