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House Pharmacology > Drug Excretion > Flashcards

Drug Excretion Flashcards

1
Q

Large intestine/rectum (biliary and faecal excretion):

Drugs secreted into ___ will ultimately pass through the large intestine and be excreted in _____. Examples include ________ and ________.

A

bile

faeces

vancomycin & vincristine

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2
Q

Tongue (excretion in saliva) : (acidic or Basic?) drugs are excreted in saliva (pH __-__) as a result of _______ of drug across the cells of the salivary glands and oral epithelium. E.g. ____,_____,_____,_____,_____

A

BASIC ; 5.8-8.4

passive diffusion

Phenytoin, diazepam, theophylline, caffeine & lithium

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3
Q

Eyes (tears)- occurs by __________ of lipo___, (protein or non-protein?) bound and (ionized or unionized?) molecules from plasma across the _____ and _____ glands.

Variations in tear pH affects movement of unbound drugs between plasma and tear. E.g. ______

A

passive diffusion

philic; non-protein

Unionized

eccrine and lacrimal

cytarabine

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4
Q

Lung: excretion occurs mainly with _______.

A

anaesthetics

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5
Q

Skin (sweat): e.g. _____, antipyrine, benzoic acid, _______, ________, _____ and ________.

A

Alcohol
Cocaine
Salicylic acid
Lead
Mercury

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6
Q

Hair: The exact mechanism by which drugs enter hair is ______. They may be deposited from the ______, which supply blood to the ______, or they may be excreted in the ___________ that coat the _______. E.g. ______,_______ & methoxyphenamine.

A

unknown
Capillaries; follicles

follicles; hair shafts

phenobarbital, methamphetamine

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7
Q

: The __________ is the most important organ involved in the elimination of drugs and their metabolites via its functional unit

A

kidney

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8
Q

nephron: _____ + ______

A

glomerulus + tubules

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9
Q

GF: filter small molecules (<_______) such as water, sugar, salt and unbound drugs via pores at the base of the glomerulus.

A

20000

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10
Q

Tubular reabsorption: Occurs by (passive or active ?) diffusion from the ____ into the _______

Tubular secretion: ____ mediated, (dependent on or independent of?) size nor protein binding. Excretes most drugs (~___%) and occurs at ______ and ______ of the nephron

A

Passive ; tubules ;peritubular capillaries

Carrier; independent of

80

both proximal and distal convoluted tubules.

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11
Q

Tubular reabsorption doesn’t require lipid solubility.
T/F

A

F
It requires lipid solubility.

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12
Q

Most of the drugs with high molecular weight like heparin, high molecular weight plasma protein such as albumin (68000) and highly protein-bound drugs such as warfarin (98%) are not excreted by glomerular filtration.

T/F

A

T

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13
Q

Water, lipid soluble drugs and other lipid soluble substances are not reabsorbed at the distal tubule by diffusion across the renal tubule into the bloodstream. Hence they are well excreted via the urine.

t/F

A

F

They are reabsorbed leading to poor excretion

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14
Q

Renal clearance (CLr) - is the ________________________________

A

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

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15
Q

Renal clearance is calculated from the ____________, ____________ and the _________ by the equation:

CLr = ________

A

plasma concentration, Cp

the urinary concentration, Cu,

volume of urine, Vu,

Cu/Cp x Vu

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16
Q

Half life (t½) – 2 types: _______ and _______ t½.

A

biological and plasma

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17
Q

Biological t½ is the time taken for ______________________________

A

a substance to lose half of its physiological, pharmacological or radioactive activity.

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18
Q

Plasma t½ is the time required for _______________

A

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

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19
Q

Plasma t½ - depends on _______ and _______ of the drug.

A

rate of excretion and metabolism

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20
Q

Plasma t½ varies between drugs. It may be very short requiring repeated administration (e.g. noradrenaline [____]) or long requiring administration once daily (e.g. methadone [____]). It may also be very long requiring once weekly intake (fluoxetine [____]).

A

2mins

15hrs

6days

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21
Q

Factors affecting drug excretion

Lipid solubility- ___eases excretion except for drugs excreted vial the ____.

A

Decr

lungs

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22
Q

Factors affecting drug excretion

pH- ____ drug becomes polar in _____ urine and vice versa resulting in increase in their excretion.

A

acidic

alkaline

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23
Q

Morphine
Serotonin
Thiazide diuretics
Serotonin
Aspirin
Indomethacin
Penicillin
Dopamine
Histamine
Quinine
Methotrexate

A

BASIC
Basic
Acidic
Basic
Acidic
Acidic
Acidic
Basic
Basic
Basic
Acidic

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24
Q

Factors affecting drug excretion

Enterohepatic cycling: (increases or reduces?) drug excretion and may (increase or decrease ?) half life.

A

Reduces
Increase

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25
Q

Enterohepatic cycling:

It involves ____ of drugs from the ____ through the _______ to the ____ where they were originally metabolized, secreted and transported in the ____ to the ______ which contain enzymes that _____ the metabolites to form _________ that are carried to the _____ again and the cycle is repeated

A

return; intestine; portal vein; liver

Bile ; intestine; hydrolyse

parent drug ; liver

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26
Q

Examples of drugs that undergo enterohepatic cycling?

A

tetracycline, flurbiprofen, digitoxin, phenytoin

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27
Q

Factors affecting drug excretion

Particle size- Except for _____ which is a macromolecule, most drugs, their metabolites and other substances with molecular weight below _____ pass freely through the glomerular capillary.

A

heparin

20000

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28
Q

Factors affecting drug excretion

Drug interaction- probenecid inhibits excretion of _____ by competing with it for tubular _____ at the _____ tubule thereby prolonging its action.

A

penicillin

secretion

proximal

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29
Q

Warfarin is mildly protein bound
T/F

A

F
Highly (98%)

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30
Q

warfarin has very small concentration in the filtrate compare to plasma.

T/F

A

T

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31
Q

Renal disease- (increases or reduces?) renal excretion of drugs.

A

Reduces

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32
Q

Normal kidney’s function can be determined by ____ which is the volume of fluid filtered through the renal glomerular capillaries into the Bowman’s capsule per unit time.

A

GFR

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33
Q

GFR: Normal ___-____

kidney disease < ___

Kidney failure < ___ [ml/min/1.73m2].

A

100-130

60

15

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34
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 and first pass metabolism.

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35
Q

Absolute bioavailability can be determined by measuring the _____ of a drug at different time when the drug is administered ________ and _______ on (same or different?) occasions.

A

plasma concentrations

orally and intravenously

Different

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36
Q

Formula for bioavailability

1) when dose is the same
_______________________

2)when dose are different
_______________________

A

AUCORAL x 100% / AUCIV

AUCORAL X DOSEIV X 100% / AUCIV X DOSEORAL

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37
Q

The plasma concentration vs time curve has the shape of a ______ and the AUC is calculated using _____ rule:

AUC= ______________

A

trapezium; trapezoidal

½ (length + breath) x height.

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38
Q

Variations in enzyme activity of the gut wall ; gastric pH; intestinal motility and other factors that affect drug absorption also affect its bioavailability.

T/F

A

T

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39
Q

Relative bioavailability is a measure of the _______________________

  Relative bioavailability formula =
A

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.

AUC TEST
_________________
AUCSTANDARD

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40
Q

To be bioequivalent the difference in relative bioavailabilities of two related drugs must not exceed ___%.

A

+/- 20

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41
Q

alkalization of urine (using _______, acetazolamide or _______) and acidification (using ________, _________ or _________)

A

sodium bicarbonate; potassium citrate

ammonium chloride

sodium phosphate or potassium phosphate

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42
Q

Phenytoin is an ________ drug

A

Anti-comvulsant

43
Q

Absolute availability can be equal to 1

T/F

A

F
It’s always less than 1

44
Q

AUC of oral takes the shape of a ?

AUC of IV takes the shape of a ??

A

Trapezium

Triangle

45
Q

In patent period- the drug is branded and marketed by the company that __________

A

does the research of the drug

46
Q

When patent period expires, can other brands market the drug?

A

Yeah

47
Q

Relative bioavailability is used to determine if 2 brands are _______

A

Bio equivalent

48
Q

Relative bioavailability can be equal to 100
T/F

A

F

Less than 100

49
Q

A drug interaction is only clinically significant if ________?

A

If the interaction affects the efficacy of one or more drugs

50
Q

Mechanism of action of Artemisinin

A

Causes radical oxidation of plasmodium to destroy it !!!

51
Q

Full meaning of ACT

A

Artemisinin based combination therapy

52
Q

Lipid solubility and pH influence the passage of drugs into the glomerular filtrate.
T/F

A

F

Lipid solubility and pH
do not influence the passage of drugs into the glomerular filtrate.

53
Q

As a general rule, weak acids can be eliminated by ______ of the urine,
whereas elimination of weak bases may be increased by ______ of the urine.

A

alkalinization

acidification

54
Q

P-glycoprotein is a transmembrane transporter protein responsible for transporting various molecules, including drugs, across ______
It is expressed in tissues throughout the body, including the liver, kidneys, placenta, intestines, and brain capillaries, and is involved in transportation of drugs from _____ to ______ That is, it “pumps” drugs _______.

A

cell membranes

tissues to blood.

out of the cells

55
Q

Thus, in areas of high expression,
P-glycoprotein (increases or reduces?) drug absorption.
In addition to transporting many drugs (into or out of ?) cells, it is also associated with ___________

A

Reduces

Out of

multidrug resistance

56
Q

Pharmacokinetic DI: occurs when one or more drug alters the _____________________ of another drug such that its plasma concentration is altered.

A

absorption, distribution, metabolism or excretion

57
Q

Pharmacodynamic DI: occurs when one or more drugs alter the _________________ of another drug.

A

pharmacological or toxic effects

58
Q

Pharmacokinetic drug interaction
• Alteration of absorption
– Calcium containing drugs (Antacids) vs tetracycline: Calcium _____ tetracycline to form a complex and (aid or prevent?) its absorption thereby reducing its plasma conc

A

chelate; prevent

59
Q

Pharmacokinetic drug interactions

Alteration of metabolism
– Efavirenz vs artemether/lumefantrine: efavirenz induces _________ enzyme which metabolises the _____ drug thereby reducing their plasma
concentration.

A

cytochrome P3A4

antimalarial

60
Q

Pharmadynamic drug interaction
• Additive toxicity
– Concomitant use of _______ and _____
increases the risk of ________ and
worsens _____ disease

A

NSAIDs and glucocorticoids

Gastric bleeding

peptic ulcer

61
Q

Pharmacodynamic drug interactions

Therapeutic failure/Reduction in efficacy
– Concomitant administration of ______ or other antioxidants with ________________________ in the treatment of malaria

A

ascorbic acid

artemisinin based combination therapy (ACT)

62
Q

Where is vancomycin Excreted from ?

A

Large intestine/ rectum

63
Q

Where is vincristine excreted from?

A

Large intestine /rectum

64
Q

Where is Phenytoin excreted from?

A

Saliva

65
Q

Where is diazepam excreted from?

A

Saliva

66
Q

Where is theophylline excreted from?

A

Saliva

67
Q

Where is caffeine secreted from ?

A

Saliva

68
Q

Where is lithium excreted from?

A

Saliva

69
Q

Where is cytarabine excreted from ?

A

Tears

70
Q

Where is Alcohol excreted from ?

A

Sweat

71
Q

Where is antipyrine excreted from?

A

Sweat

72
Q

Where is benzoic acid excreted from?

A

Sweat

73
Q

Where is cocaine excreted from?

A

Sweat

74
Q

Where is salicylic acid excreted from?

A

Sweat

75
Q

Where is lead excreted from?

A

Sweat

76
Q

Where is mercury excreted from?

A

Sweat

77
Q

Where is aspirin excreted from?

A

Breast milk

78
Q

Where is phenobarbital excreted from?

A

Hair

79
Q

Where is methamphetamine excreted from?

A

Hair

80
Q

Where is methoxyphenamine excreted from?

A

Hair

81
Q

Plasma half life of methadone is _____

A

15hrs

82
Q

Plasma half life of fluoxetine is ______

A

6days

83
Q

alkalization of urine using _______,_______, or ________

A

sodium bicarbonate, acetazolamide or potassium citrate

84
Q

acidification of urine using ______,_______, or _______

A

ammonium chloride, sodium phosphate or potassium phosphate

85
Q

quinine

Acidic or basic

A

BASIC

86
Q

probenecid

Acidic or basic

A

BASIC

87
Q

morphine

Acidic or basic

A

Basic

88
Q

histamine

Acidic or basic

A

BASIC

89
Q

serotonin

Acidic or basic

A

BASIC

90
Q

dopamine

Acidic or basic

A

BASIC

91
Q

pethidine

Acidic or basic drug?

A

BASIC

92
Q

aspirin

Acidic or basic

A

Acidic

93
Q

penicillin

Acidic or basic

A

Acidic

94
Q

methotrexate

Acidic or basic

A

Acidic

95
Q

indomethacin

Acidic or basic

A

Acidic

96
Q

frusemide

Acidic or basic drug?

A

Acidic

97
Q

thiazide diuretics.

Acidic or basic drugs

A

Acidic drugs

98
Q

tetracycline

Undergoes enterohepatic cycling

T/F

A

T

99
Q

chloramphenicol

Undergoes enterohepatic cycling
T/F

A

T

100
Q

digitoxin

Undergoes enterohepatic cycling
T/F

A

T

101
Q

phenytoin

Undergoes enterohepatic cycling
T/F

A

T

102
Q

oestradiol

Doesn’t undergo enterohepatic cycling?

T/F

A

F

103
Q

First pass effect can occur in;
- ___ (when drug is taken _____)
- ___ (through ______)
- ____ (_______ drugs)

A

GI; orally

Skin; transdermal patch

Lungs; inhalational

House Pharmacology (50 decks)

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