medicinal chemistry Flashcards

1
Q

the four types of administration routes are…
1. oral
2. ???
3. rectal
4. topical

A

parental

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2
Q

capsules, suspensions, solutions and tablets are all ______ administrated

A

orally

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3
Q

what are two rectal dosage forms?

A

suppositories, creams

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4
Q

what are three types of injections

A
  • intravenous
  • subcutaneous
  • muscular
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5
Q

why are there different administrative routes? (2 short)

A
  • increase bioavailability of drug
    • prevents degradation by acidic pH in the stomach environment
  • incr patient compliance
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6
Q

what is bioavailability?

A

fraction of of administered dosage that enters the blood stream

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7
Q

which type of administration has 100% bioavailability?

A

parental

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8
Q

what is pharmocokinetics? (short recap)

A

what the body does to the drug after it enters the body

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9
Q

the four processes of pharmokinetics are…

A
  1. absorption
  2. distribution
  3. metabolism
  4. elimination

(All Dogs Make Eggs)

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10
Q

what is one way absorption is negatively affected?

A

poor solubility in water -> poor uptake

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11
Q

distribution is affected by the _______ity and _____ity of drugs

A

hydrophilicity, lipophilicity

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12
Q

what affects the hydrophilicity and lipophilicity of drugs?

A

the functional groups present on compounds

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13
Q

what type of drug administration is usually affected by metabolism?

A

oral

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14
Q

drugs that become metabolites undergo ______________

A

first pass metabolism

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15
Q

how does metabolism affect bioavailability? (3)

A
  • drugs experience ‘first-pass metabolism’ by the liver
  • cannot exert therapeutic affects
  • this significantly affects F
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16
Q

what is the therapeutic window? (short def.)

A

the range of acceptable dosage strengths where the drug will exert its therapeutic effect without causing toxic effects

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17
Q

what is the formula for therapeutic index for animals

A

LD50/ED50

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18
Q

what is the formula for therapeutic index for humans

A

TD50/ED50

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19
Q

is a high therapeutic index good? why?

A
  • yes
  • greater safety margin btw effective and toxic/lethal dose
  • when taken in higher doses than required for it to exert therapeutic effect, the drug will still be safe
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20
Q

how does aspirin work as a mild analgesic?

A

it binds to COX 2 enzyme and prevents it from releasing prostaglandin

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21
Q

aspirin prevents pain detection at the source by

A

preventing nerve messages from being sent to the brain

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22
Q

aspirin reduces swelling by

A
  • preventing dilation of blood vessels
  • decr swelling
    • reduces inflammatory response
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23
Q

what does prostaglandin do? (2)

A
  • send nerve messages to brain -> pain detection at source
  • causes inflammatory response -> dilation of blood vessels -> swelling -> incr pain
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24
Q

what reagents and conditions are required for the synthesis of aspirin?

A
  • reagents: salicylic acid, ethanoic anhydride
  • cond: catalyst H2SO4, warm e mixture
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25
Q

what are the products of aspirin synthesis

A

aspirin + ethanoic acid

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26
Q

write out the reaction of aspirin synthesis

A

-

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27
Q

how is aspirin purified from aspirin synthesis?

A
  • dissolved and heated in ethanol
  • recrystallisation in ethanol -> due to low solubility
  • filtration
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28
Q

what does a lower than expected melting point of aspirin tell us?

A

there are impurities

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29
Q

what is the m.p. of salicylic acid?

A

159ºC

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30
Q

what is the m.p. of aspirin

A

138-140ºC

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31
Q

what method can be used to differentiate between aspirin and salicylic acid?

A
  • IR spectroscopy
    • aspirin: presence of C=O peak
    • salicylic acid: presence of O-H peak
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32
Q

what does synergistic mean?

A

when taken together, the drugs have a greater combined effect than individual effects

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33
Q

what are 2 other purposes for aspirin?

A
  • anticoagulant
  • synergistic effects w alcohol
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34
Q

why is aspirin made into a salt?

A
  • improve solubility of aspirin in water
  • incr F
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35
Q

write the reaction of how aspirin is made into a salt

A

-

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36
Q

what is penicillin

A

an antibiotic

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37
Q

why is penicillin so reactive?

A

it has a beta-lactam ring which has ring strain

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38
Q

how does the beta-lactam ring in penicillin kill bacteria? (2)

A
  • binds irreversibly to enzyme transpeptidase in bacteria
  • disrupts formation of bacterial cell wall
  • when water enters bacteria, bacteria lyses
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39
Q

why is penicillin modified? (2)

A
  1. to improve stability of drug in low pH environment
    • improve oral F
  2. overcome antibiotic resistant bacteria
    • has enzyme penicillinase which prematurely opens up beta-lactam ring
    • prevents bacteria fr recognising drug
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40
Q

why is there increased antibiotic resistance?

A
  • overprescription of antibiotics
  • when patients do not complete the full course of antib
  • use of antibodies in animal feed -> enters food chain -> humans end up eating it
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41
Q

how do opiates function as strong analgesics?

A
  • bind reversibly to opiate receptors in CNS
  • prevents transmission of nerve impulses
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42
Q

how is morphine derived?

A

from opium

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43
Q

which opiate is methylated morphine?

A

codeine

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44
Q

diamorphine is the ________ form of morphine

A

esterified

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45
Q

why is diamorphine the most potent?

A
  • it is least polar
  • it can cross the lipophilic blood brain barrier most easily
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46
Q

codeine and diamorphine are _____, precursors to the active form morphine

A

pro-drugs

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47
Q

what are pro-drugs

A
  • inactive form of drug
  • metabolised in the body into active form
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48
Q

what reagent can be used to react convert morphine into diamorphine

A

ethanoic anhydride

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49
Q

what are 2 advantages of opiate usage?

A
  • provides stronger + faster pain relief
  • suppresses cough reflex
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50
Q

what are 3 disadvantages of opiate usage?

A
  • addiction
  • tolerance -> overdose
  • constipation
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51
Q

what is tolerance?

A

it is when a higher dosage is required to exert the same effect

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52
Q

why is tolerance dangerous?

A

higher dosages may reach lethal dosage –> overdose

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53
Q

what condition is caused by excessive production of HCl?

A

dyspepsia

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54
Q

what are three things you can take to counter dyspepsia

A
  • ranitidine
  • omeprazole/esomeprazole
  • antacids
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55
Q

how does ranitidine counter dyspepsia?

A
  • competitive inhibitor of H2-receptor
  • prevents histamine from binding
  • prevents parietal cells from releasing HCl
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56
Q

ranitidine inhibits ____ while omeprazole/esomeprazole inhibits ____

A

H2-receptor, proton pump

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57
Q

how does omeprazole/esomeprazole counter dyspepsia?

A
  • inhibits proton pumps
  • directly prevents parietal cells from releasing H+
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58
Q

antacids counter dyspepsia by…

A

neutralising excess acid

59
Q

why aren’t strong bases used as antacids?

A
  • they are strong bases –> caustic
  • damage stomach lining
60
Q

what’s the difference between viruses and bacteria? (focus on virus) (2)

A
  • viruses need a host to replicate and survive (bacteria don’t need)
  • viruses consist of proteins and RNA (bacteria has a complex cellular structure)
61
Q

antivirals function to _________ with host or virus

A

interfere

62
Q

how do antivirals work? (3 short)

A
  • interfere w host DNA -> virus cannot replicate
  • interfere w host cell membrane -> virus cannot enter
  • interfere w virus -> virus cannot leave
63
Q

what does oseltamivir/zanamivir act against?

A

influenza

64
Q

how does oseltamivir/zanamivir work as an antiviral? (4)

A
  • competitive inhibitors of neuraminidase enzyme
  • neuraminidase cleaves a sialic acid moiety from the host cell -> allows virus to leave
  • oseltamivir competes with sialic acid moiety for the active site
  • prevents exit of viral molecules
65
Q

why must oseltamivir/zanamivir be administered promptly upon infection?

A
  • otherwise the virus would have already proliferated
  • this renders the drug ineffective
66
Q

why is HIV so difficult to kill (3)

A
  • kills T helper cells
  • mutates rapidly -> develops resistance
  • remains dormant
67
Q

where is taxol obtained from

A

bark of pacific yew trees

68
Q

why is taxol synthetically produced

A

extremely low yield fr the trees

69
Q

taxol synthetically produced by… (short)

A

using 10-deacylbaccatin from needles and leaves of European yew trees

70
Q

production of taxol is highly controlled by ________

A

chiral auxillaries

71
Q

why are chiral auxillaries necessary in the production of taxol?

A
  • chiral auxilliaries are used to ensure only products w desired stereochemistry is produced
  • otherwise taxol could potentially bind to off-target and lead to toxicity
72
Q

why does the production of taxol need to be highly controlled?

A
  • taxol has 11 chiral centres
  • if it binds to off targets it could lead to toxicity
73
Q

how are chiral auxillaries used to produce the desired enantiomer of Taxol?

A
  • the chiral auxiliary combines with the non-chiral reactant to form a chiral intermediate
  • ensures only the desired enantiomer is produced
  • removed and recycled
74
Q

in chemotherapy, taxol is used to bind to _______ in ________ cells

A

tubulin in cancer cells

75
Q

how does the binding of taxol to tublin prevent the proliferation of cancer cells

A
  • prevents spindle fibres from breaking down
  • prevents cell division
76
Q

what is emitted in alpha decay

A

helium nucleus, 4,2 He

77
Q

what is emitted in beta decay

A

electron, 0, -1 e-

78
Q

what is the equation used to find the rate constant?

A

t1/2= ln2/k

t1/2 – half life of isotope
k = decay constant

79
Q

what are the types of diagnostic imaging?

A
  • nuclear imaging
  • magnetic resonance imaging (MRI)
80
Q

what is nuclear imaging?

A

diagnostic technique that uses tracers that emit radiation and can be detected by using positron emission tomography (PET)

81
Q

what type of diagnostic imaging uses gamma radiation?

A

nuclear imaging

82
Q

how can gamma radiation be detected in nuclear imaging?

A

with positron emission tomography (PET)

83
Q

what tracer is used for nuclear imaging?

A

Technetium-99m

84
Q

why is Technetium-99m used as a tracer for nuclear imaging? (3)

A
  1. it has a short half-life -> minimises exposure for the patient
  2. emits low-energy radiation -> safe for the patient
  3. binds to a range of biologically-active substances -> versatile
85
Q

magnetic resonance imaging employs the theories of _______ spectroscopy to provide ____ images

A

NMR, 2D/3D

86
Q

why is MRI preferred over nuclear imaging?

A

it does not use ionising radiation

87
Q

________ emit high energy radiation that kills off cancer cells

A

radionuclides

88
Q

how does radiotherapy work?

A

it uses radionuclides that emit high energy radiation that can kill off cancer cells

89
Q

what are radionuclides used for?

A
  1. cancer treatment
  2. medical imaging
90
Q

what are 2 common radionuclides used in radiotherapy?

A
  • Lutetium-177
  • Yttrium-90
91
Q

why are Lutetium-177 and Yttrium-90 used as radionuclides for radiotherapy?

A
  • they emit beta radiation that destroys cancer cells
  • Lut-177 also emits gamma radiation that allows for imaging
92
Q

Cobalt-60 is used for…

A

external radiotherapy

93
Q

how is Cobalt-60 effective in damaging cancer cells for external radiotherapy?

A
  • fired at site of cancer from external source
  • undergoes beta decay
  • it emits gamma radiation that can penetrate and damage cancer cells
94
Q

what is Lead-212 is used for?

A

internal radiotherapy

95
Q

gamma radiation in external radiotherapy is from an _________ source

A

external

96
Q

internal radiotherapy requires a _________

A

carrier drug/protein/antibody

97
Q

how does internal radiotherapy work?

A

a radioactive material is ingested into the body with a carrier drug/protein/antibody to allow for treatment to work

98
Q

name two types of internal radiotherapy

A
  1. targeted alpha therapy (TAT)
  2. boron neutron capture therapy (BNCT)
99
Q

what element is involved in targeted alpha therapy (TAT)?

A

Lead-212

100
Q

how does Lead-212 treat cancer?

A

it undergoes alpha decay which can kill target cells

101
Q

what treatment would be used for cancers that have metastasised?

A
  • internal radiotherapy
  • targeted alpha therapy (TAT) where Lead-212 is used
102
Q

why is TAT used for treating metastasised cancers?

A
  • carrier drug carries radiation source directly to cancer cells
  • several sites in the body can be targeted at the same time
103
Q

which therapy uses Boron-10?

A
  • internal therapy
  • boron neutron capture treatment
104
Q

which therapy uses Cobalt-60?

A

external

105
Q

how does boron neutron capture therapy (BNCT) work?

A
  • it employs Boron-10 which ‘captures’ neutrons which are fired at it from an external source
  • forms Boron-11 which undergoes alpha decay
106
Q

how is Boron-10 is administered?

A

via intravenous injection

107
Q

what is the equation for the decay of Boron-10 in BNCT?

A

-

108
Q

for treatment of neck/head/brain cancer, what therapy would be used?

A

boron neutron capture therapy (BNCT)

109
Q

why are alpha particles effective for head cancer therapies?

A
  • they have high ionising density -> thus high probability of killing cells at target
  • alpha particle radiation is short range -> minimises unwanted irradiation of normal tissue surrounding targeted cancer cells
110
Q

what are the side effects of radiotherapy? (3)

A
  • fatigue
  • nausea
  • hair loss
111
Q

why does radiotherapy have side effects?

A
  • radionuclides emit ionising radiation
  • this causes formation of reactive radicals and damages DNA
112
Q

why is hair loss a common effect of radiotherapy?

A

radionuclides damage DNA of hair follicles

113
Q

how can substances be isolated? (2)

A
  1. solvent extraction
  2. fractional distillation
114
Q

what is the principle that solvent extraction uses?

A

it separates compounds based on their preference for water or organic solvent

115
Q

how does solvent extraction work? (5)

A
  • hexane and water are added to a separating funnel
  • solid mixture is added and shaken vigorously
  • compound will separate out based on their hydrophilicity and lipophilicity -
  • empty the funnel to obtain desired layer
  • let the solvent evaporate -> thus obtaining the desired compound
116
Q

what is the principle that fractional distillation uses?

A

separates compounds based on their difference in volatilities

117
Q

what is the eqn for mole fraction of A in vapour?

A

vapour pressure of A / total vapour pressure

118
Q

how does fractional distillation work?

A
  1. components w lower bp evaporate first
  2. it rises through the fractionating column where it repeatedly evaporates and condenses
  3. vapour enters condenser, is cooled to form a liq and collected
119
Q

what is the equation for vapour pressure

A

Xa x Pa
Xa= mole fraction of A in mixutre
Pa= vapour pressure of pure A

120
Q

what is the equation for total vapour pressure

A

Xa x Pa + Pb x Xb

where P is vapour pressure
and X is mole fraction

121
Q

what is the equation for mole fraction

A

vapour pressure of benzene /total vapour pressure

122
Q

how are steroids detected?

A

by using gas chromatography-mass spectrometry (GCMS)

123
Q

how does gas chromatography-mass spectrometry (GCMS) work?

A
  • sample is vaporised
  • separated based on boiling points –> more volatile cmpds move faster
  • separated based on affinity for stationary and mobile phase –> cmpds w greater affinity for stationary are retained longer
  • mass spec then can be compared to known compounds for identification
124
Q

what is the principle of GCMS?

A
  • components are separated by affinity for stationary and mobile phase
  • AND b.p.s
125
Q

what are the two ways to detect ethanol?

A
  1. breathalysers
  2. intoximeters
126
Q

intoximeters use ______ _____ of which the _______________ generated can be detected

A

fuel cells, electric current

127
Q

how do breathalysers work?

A
  • they detect ethanol when K2Cr2O7 oxidises ethanol to ethanoic acid
  • colour change is detected -> orange to green
128
Q

how do fuel cell breathalysers work?

A
  • at the anode, ethanol in breath is oxidised to ethanoic acid
  • electrons pass through external circuit to the cathode
  • at the cathode, O2 is reduced to H2O
  • current is proportional to alcohol concentration in blood
129
Q

what are the 3 principles of green chemistry you should note?

A
  1. safer solvents and auxillaries
  2. atom economy
  3. waste prevention
130
Q

why are some solvents unsafe? (3)

A
  • they may be carcinogenic
  • highly flammable and explosive
  • contaminate the environment
131
Q

what are 2 safe solvents

A
  • water
  • ethanol
132
Q

what is an example of a switch to safer solvent?

A
  • synthesis of analgesic Lyrica
  • reduces 3 million tonnes of CO2 emissions by switching to water as the main solvent
133
Q

increasing atom economy reduces…

A

the no. of byproducts in a synthetic route

134
Q

what is an example for increased atom economy?

A
  • synthesis of ibuprofen
  • 6 steps reduced to 3
  • increased atom economy from 40% to 77%
135
Q

what is waste prevention in green chemistry?

A

prioritising reducing the amount of waste created instead of cleaning up and treating waste

136
Q

what is an example of improved waste prevention

A
  • production of Viagra
  • used a modified reaction route that reduced waste by 75%
137
Q

what are the types of waste?

A
  1. nuclear
  2. antibiotic
138
Q

what are the types of nuclear waste?

A
  • high-lvl waste
  • low-lvl waste
139
Q

what is high-lvl waste?

A

waste that gives off large amts of ionising radiation with a long half life

140
Q

what is short-lvl waste?

A

waste that gives off short amts of ionising radiation w a short half life

141
Q

how can you dispose of high-lvl waste?

A
  • stored under water in cooling ponds for 5-10 yrs
  • transferred to dry storage in heavily shielded structure buried underground
142
Q

how can you dispose of low-lvl nuclear waste?

A
  • stored in shielded containers until the radiation drops to a safe level
  • disposed in landfills
143
Q

why is antibiotic waste bad?

A
  • if antibiotics are improperly disposed and overprescribed -> this incrs exposure of bacteria to the antibiotic
  • hastens genetic mutation of bacteria
  • allows bacteria to develop antibiotic resistance
144
Q

how can we prevent antibiotic waste? (4)

A
  • minimised release of antibiotics into the environment
  • destruction of activity of the drug before disposal
  • consumers must avoid overuse
  • consumers must complete the full course of prescribed med