Drug Excretion, Bioavailability And Bio equivalence

Question 1

Drugs excretion is the irreversible __________ of unchanged _________ ________or their __________ from the body via various organs of which the __________ is major and most important

Answer 1

Elimination

Parent drugs

Metabolites

Kidney

Question 2

Organs of drug excretion and their product (8)

Answer 2

Kidney: urine
Tongue : saliva
Skin: sweat
Breast: breast milk
Lungs: breathe
Rectum/intestine: bile- faeces
Eye: tears
Hair

Question 3

Large intestine excreted drugs include 2

Answer 3

Vancomycin (Antibiotic)
Vincristine (chemotherapy)

Question 4

________ drugs are excreted in saliva as a result of __________ diffusion of drug across the cells of the salivary glands and oral ___________.

Answer 4

Basic

Passive

Epithelium

Question 5

Saliva has a pH of

Answer 5

5.8-8.4

Question 6

Examples of tongue excreted saliva

Answer 6

Phenytoin (anti- epileptic/ anti- convulsant)
diazepam (anxiolytic)
theophylline (bronchodilator: asthma, COPD)
caffeine (stimulant)
lithium (mood stabilizer)

Question 7

Eye excretion occurs by ________ diffusion of __________, non-protein bound and _________ molecules from plasma across the _________ and ___________ glands.

Answer 7

Passive
Lipophilic
Unionized/ non- ionized
Eccrine & Lacrimal

Question 8

In eye excretion, variations in __________affects movement of unbound drugs between plasma and tear.

Answer 8

pH of tears

Question 9

Examples of drug excreted by tears

Answer 9

Cytarabine : chemotherapy

Question 10

Lung excretion occurs mainly with

Answer 10

Anaesthetics

Question 11

Drugs excreted by the skin include (7)

Answer 11

Alcohol
antipyrine
benzoic acid
cocaine
salicylic acid
lead
mercury

Question 12

Most drugs are excreted through breast milk T/F

Answer 12

True

Question 13

The exact mechanism by which drugs enter hair is known. They may be deposited from the capillaries, which supply blood to the follicles, or they may be excreted in the ________, _________ or __________ that coat the hair shafts
T/F

Answer 13

False. It is unknown

sebum, oil, or sweat

Question 14

Examples of drugs excreted from hair is

Answer 14

phenobarbital (barbiturates and anticonvulsant)

methamphetamine (CNS stimulant)

methoxyphenamine(bronchodilator)

Question 15

The _________ is the most important organ involved in the elimination of via its functional unit

Answer 15

Kidney

Drugs and their metabolites

Question 16

nephron= __________ + ________

Answer 16

Glomerulus + Tubules

Question 17

Renal excretion = __________- _________+ ___________

Answer 17

Glomerular filtration (GF) – tubular reabsorption (TR) + tubular secretion (TS).

Question 18

Glomerular filtration filters small molecules. Less than

Answer 18

20,000

Question 19

Tubular reabsorption: Occurs by _______ diffusion from the _________ into the _________ capillaries, and requires _________ ______________

Answer 19

Passive

Tubules

Peritubular

Lipid solubility

Question 20

Tubular secretion: Carrier mediated, independent of ____ nor _________ ________.

Excretes most drugs (~ ___%) and occurs at both proximal and distal convoluted tubules.

Answer 20

size nor protein binding.

80%

Question 21

Most of which drugs are not excreted by glomerular filtration.

Answer 21

drugs with high molecular weight like heparin

high molecular weight plasma protein such as albumin (68000)

highly protein-bound drugs such as warfarin (98%)

Question 22

Water, lipid soluble drugs and other lipid soluble substances are _________ at the distal tubule by _________ across the renal tubule into the bloodstream. Hence they are ______ excreted via the urine.

Answer 22

Reabsorbed

Diffusion

Poorly

Question 23

ACT means

Answer 23

Artemisinin- based Combination therapy

Question 24

Define renal clearance

Answer 24

is the volume of plasma containing
the amount of substance that is excreted by the kidney per unit time.

Question 25

Formulae for renal clearance

Answer 25

Urine volume * urine concentration / Plasma concentration

Question 26

The types of half life are T1/2

Answer 26

Biological half time Plasma half time

Question 27

Biological half life is the time taken for a substance to lose half of its __________, __________ or __________ activity

Answer 27

physiological pharmacological radioactive

Question 28

Plasma t1⁄2 is the time required for?

Answer 28

the plasma concentration of a drug to be reduced to half.

Question 29

Plasma half time depends on what & what

Answer 29

Rate of excretion and Metabolism of the drug

Question 30

Plasma t1⁄2 varies between drugs. It may be very short requiring repeated administration e.g.? or long requiring administration once daily e.g. ? Or very long requiring once weekly intake eg?

Answer 30

Noradrenaline 2 minutes (increase blood pressure) Methadone 15 hours (pain relief and treat drug addiction) Fluoxetine 6 days (antidepressant)

Question 31

7 Factors affecting Drug Excretion

Answer 31

Lipid Solubility pH Enterohepatic cycling Particle size Protein binding Drug interaction Renal disease

Question 32

About lipid solubility

Answer 32

Excretion is decreased except for drugs exerted via the lungs

Question 33

About pH, acidic drug becomes polar in ________

Answer 33

alkaline urine Alkaline drug becomes polar (ionized) in acidic urine Thus increasing excretion

Question 34

Therefore for abosorption acid? While for excretion

Answer 34

Acid should be in acidic solution Acid should be in alkaline medium

Question 35

Drugs for alkalization of urine

Answer 35

sodium bicarbonate acetazolamide potassium citrate

Question 36

Drugs for acidification of urine

Answer 36

ammonium chloride sodium phosphate potassium phosphate

Question 37

Basic drugs include

Answer 37

quinine probenecid morphine histamine serotonin dopamine pethidine

Question 38

Acidic drugs are

Answer 38

aspirin penicillin methotrexate indomethacin frusemide thiazide diuretics

Question 39

Enterohepatic cycling does 2 things

Answer 39

reduces drug excretion may increase half life.

Question 40

Enterohepatic recycling involves return of drugs from (through the portal vein) liver where they were originally metabolized, secreted and transported in the bile to the intestine which contain enzymes that _________ the metabolites to form ___________ that are carried to the liver again and the cycle is repeated

Answer 40

Hydrolyze Parent drug enterohepatic recycling (or enterohepatic circulation) involves the circulation of metabolized and non-metabolized compounds (including physiologic compounds and xenobiotics) between the intestine and the liver. Some xenobiotics and some endogenous substances (e.g., bile acids) can be reabsorbed after their elimination into the intestine by the liver, entering an enterohepatic cycle

Question 41

Examples of drugs that go through enterohepatic recycling because they are secreted by the liver into bile

Answer 41

tetracycline chloramphenicol flurbiprofen leflunomide colchicine digitoxin phenytoin oestradiol

Question 42

Which drug is a macromolecule and can’t be easily excreted

Answer 42

Heparin

Question 43

most drugs, their metabolites and other substances with molecular weight below _________ pass freely through the glomerular capillary and are excreted

Answer 43

20,000

Question 44

plasma albumin has a molecular weight of ________ and cannot pass freely through the glomerular capillary. Hence ____________ which is highly protein bound __%has very small concentration ___% in the filtrate compared to plasma.

Answer 44

68,000 Warfarin 98 2

Question 45

____________ inhibits the excretion of penicillin

Answer 45

Probenecid by competing with it for tubular secretion at the proximal tubule thereby prolonging its action

Question 46

How does renal disease affect renal excretion of drugs

Answer 46

It reduces excretion

Question 47

Risk factors for kidney disease include

Answer 47

diabetes high blood pressure family history older age ethnic group smoking.

Question 48

Normal kidney function can be determined by?

Answer 48

Glomerular Filtration rate

Question 49

GFR is ?

Answer 49

the volume of fluid filtered through the renal glomerular capillaries into the Bowman’s capsule per unit time

Question 50

GFR in Normal kidney Kidney disease Kidney failure

Answer 50

100-130 Less than 60 Less than 15

Question 51

Unit of GFR

Answer 51

ml/min/1.73m2 Body surface

Question 52

Bioavailability is a measurement of the ________ & __________ to which the active ingredient in a drug product becomes available at the site of action or in _________ ____________

Answer 52

Rate & extent Systemic circulation

Question 53

Absolute bioavailability is the _________ of an active ingredient of an ___________ administered drug that reaches _________ ___________ as an intact drug (unchanged)

Answer 53

fraction orally systemic circulation unchanged)

Question 54

Absolute bioavailability of drugs administered intravenously is ______% but it is less for drugs administered through other routes due to __________________ and _______________

Answer 54

100% Incomplete absorption First pass metabolism

Question 55

AUC means

Answer 55

Area under plasma conc vs time curve

Question 56

Absolute bioavailability (F) formula if doses are the same

Answer 56

▪ F= AUCoral / AUCiv x 100%

Question 57

F formula for different doses is

Answer 57

F= AUCoral X DOSEiv / AUCiv X DOSEoral X 100%

Question 58

The plasma concentration vs time curve has the shape of? and the AUC is calculated using?

Answer 58

A trapezium Trapezoidal rule which is Area= 1⁄2 (length + breath) x height.

Question 59

Factors that affect bioavailability also affect absorption T/F

Answer 59

True

Question 60

Factors that affect bioavailability is

Answer 60

Variations in enzyme activity of the gut wall ; gastric pH; intestinal motility

Question 61

What is relative bioavailability?

Answer 61

Relative bioavailability is a measure of the systemic availability of a generic or test drug product in comparaism to that of a Reference standard drug product containing the same active ingredient when they are administered through the same route in the same dosage form. Relative bioavailability = AUC test/ AUC standard

Question 62

In bio equivalence, A generic drug is bioequivalent to a reference standard drug if their relative bioavailability do not show SSD when both drug products containing the same active ingredient in the same chemical and dosage forms are administered at the same dose through the same route and under the same experimental conditions.

Answer 62

SSD?

Question 63

To be bioequivalent the difference in relative bioavailabilities of two related drugs must not exceed +|- ?

Answer 63

20%