Issar - Drug Excretion Flashcards
What is the major organ of drug excretion
kidney
The functional unit of the kidney is the ____ and includes the BC, _____, LOH, distal tubule, and _____
nephron; proximal tubule
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 ___ ____.
bowmans capsule;
proximal tubule;
LOH;
distal tubule
What are the three major renal excretion processes
- Glomerular filtration
- Active tubular secretion
- tubular reabsorption
Renal excretion = _____ - reabsorption + ______
filtration; secretion
What is normal GFR? how much of drug gets filtered, what about reabsorbed?
110- 130 ml/min; 10%; 90%
____ clearance is is equal to the glomerular _____ rate bc inulin gets filtered only.
inulin; filtration
What is renal clearance?
CLR, is the volume of plasma from which all the substance is removed by the kidney in unit time.
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.
carrier; inhibition; penicillin; probenecid
_____ may have clearance values approaching the renal plasma flow rate up to 650 ml
PAH
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
lipids; pH; lipid
If Cldrug/Clinulin <1 then:
drug is being partially reabsorbed
If Cldrug/Clinulin = 1 then:
drug is being filtered
If Cldrug/Clinulin > 1 then:
drug is being actively secreted.
____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
creatinine; GFR; inversely
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
active; anions; polar; 500
what is entero hepatic circulation? What enzyme helps this?
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;
What are factors that affect biliary secretion
- liver disease or injury
- age; infants and elderly
- chronic administration of drugs inc. bile flow
- competition between drugs
During pulmonary excretion, rate of drug loss is dependent on:
- respiration rate
- pulmonary blood flow
- drug solubility
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
cardiac; High
Sweat and saliva have minor importance in drug excretion. You can only ____ the drug, even for IV administeered drugs
taste
Drug presence in milk is dependent on:
- maternal blood conc.
- plasma protein binding
- lipid solubility
- pKa
MIlk is more ___ than plasma, therefore ___ drugs accumulate. ___ soluble drugs accumulate in milk fat.
acidic; basic; lipid
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.
Quinidine