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FPP Pharmacology > Drug Excretion, Bioavailability And Bio equivalence > Flashcards

Drug Excretion, Bioavailability And Bio equivalence Flashcards

1
Q

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

A

Elimination

Parent drugs

Metabolites

Kidney

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2
Q

Organs of drug excretion and their product (8)

A

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

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3
Q

Large intestine excreted drugs include 2

A

Vancomycin (Antibiotic)
Vincristine (chemotherapy)

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4
Q

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

A

Basic

Passive

Epithelium

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5
Q

Saliva has a pH of

A

5.8-8.4

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6
Q

Examples of tongue excreted saliva

A

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

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7
Q

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

A

Passive
Lipophilic
Unionized/ non- ionized
Eccrine & Lacrimal

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8
Q

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

A

pH of tears

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9
Q

Examples of drug excreted by tears

A

Cytarabine : chemotherapy

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10
Q

Lung excretion occurs mainly with

A

Anaesthetics

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11
Q

Drugs excreted by the skin include (7)

A

Alcohol
antipyrine
benzoic acid
cocaine
salicylic acid
lead
mercury

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12
Q

Most drugs are excreted through breast milk T/F

A

True

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13
Q

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

A

False. It is unknown

sebum, oil, or sweat

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14
Q

Examples of drugs excreted from hair is

A

phenobarbital (barbiturates and anticonvulsant)

methamphetamine (CNS stimulant)

methoxyphenamine(bronchodilator)

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15
Q

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

A

Kidney

Drugs and their metabolites

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16
Q

nephron= __________ + ________

A

Glomerulus + Tubules

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17
Q

Renal excretion = __________- _________+ ___________

A

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

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18
Q

Glomerular filtration filters small molecules. Less than

A

20,000

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19
Q

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

A

Passive

Tubules

Peritubular

Lipid solubility

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20
Q

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

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

A

size nor protein binding.

80%

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21
Q

Most of which drugs are not excreted by glomerular filtration.

A

drugs with high molecular weight like heparin

high molecular weight plasma protein such as albumin (68000)

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

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22
Q

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.

A

Reabsorbed

Diffusion

Poorly

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23
Q

ACT means

A

Artemisinin- based Combination therapy

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24
Q

Define renal clearance

A

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

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25
Q

Formulae for renal clearance

A

Urine volume * urine concentration
/
Plasma concentration

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26
Q

The types of half life are

T1/2

A

Biological half time
Plasma half time

27
Q

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

A

physiological
pharmacological
radioactive

28
Q

Plasma t1⁄2 is the time required for?

A

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

29
Q

Plasma half time depends on what & what

A

Rate of excretion and
Metabolism of the drug

30
Q

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?

A

Noradrenaline 2 minutes (increase blood pressure)

Methadone 15 hours (pain relief and treat drug addiction)

Fluoxetine 6 days (antidepressant)

31
Q

7 Factors affecting Drug Excretion

A

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

32
Q

About lipid solubility

A

Excretion is decreased except for drugs exerted via the lungs

33
Q

About pH,

acidic drug becomes polar in ________

A

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

34
Q

Therefore for abosorption acid?
While for excretion

A

Acid should be in acidic solution

Acid should be in alkaline medium

35
Q

Drugs for alkalization of urine

A

sodium bicarbonate
acetazolamide
potassium citrate

36
Q

Drugs for acidification of urine

A

ammonium chloride
sodium phosphate
potassium phosphate

37
Q

Basic drugs include

A

quinine
probenecid
morphine
histamine
serotonin
dopamine
pethidine

38
Q

Acidic drugs are

A

aspirin
penicillin
methotrexate
indomethacin
frusemide
thiazide diuretics

39
Q

Enterohepatic cycling does 2 things

A

reduces drug excretion
may increase half life.

40
Q

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

A

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

41
Q

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

A

tetracycline
chloramphenicol
flurbiprofen
leflunomide
colchicine
digitoxin
phenytoin
oestradiol

42
Q

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

A

Heparin

43
Q

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

A

20,000

44
Q

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.

A

68,000

Warfarin

98

2

45
Q

____________ inhibits the excretion of penicillin

A

Probenecid

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

46
Q

How does renal disease affect renal excretion of drugs

A

It reduces excretion

47
Q

Risk factors for kidney disease include

A

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

48
Q

Normal kidney function can be determined by?

A

Glomerular Filtration rate

49
Q

GFR is ?

A

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

50
Q

GFR in
Normal kidney
Kidney disease
Kidney failure

A

100-130

Less than 60

Less than 15

51
Q

Unit of GFR

A

ml/min/1.73m2

Body surface

52
Q

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

A

Rate & extent

Systemic circulation

53
Q

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

A

fraction
orally
systemic circulation
unchanged)

54
Q

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

A

100%

Incomplete absorption

First pass metabolism

55
Q

AUC means

A

Area under plasma conc vs time curve

56
Q

Absolute bioavailability (F) formula if doses are the same

A

▪ F= AUCoral / AUCiv x 100%

57
Q

F formula for different doses is

A

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

58
Q

The plasma concentration vs time curve has the shape of?

and the AUC is calculated using?

A

A trapezium

Trapezoidal rule which is

Area= 1⁄2 (length + breath) x height.

59
Q

Factors that affect bioavailability also affect absorption T/F

A

True

60
Q

Factors that affect bioavailability is

A

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

61
Q

What is relative bioavailability?

A

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

62
Q

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.

A

SSD?

63
Q

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

A

20%

FPP Pharmacology (11 decks)

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