Option D - Medicinal Chemistry Flashcards
1
Q
What was aspirin extracted from?
A
- willow bark
2
Q
What was morphine extracted from?
A
- poppy seeds
3
Q
What is a drug or medicine?
A
- any chemical (natural or human-made) that does one or more of the following:
alters incoming sensory sensations, alters mod or emotions, alters the physiological state
4
Q
What are drugs or medicine usually taken for and how do they accomplish it?
A
- to improve health
- accomplish this by assisting the body in its natural healing process
5
Q
What is the “placebo” effect?
A
- when the body can be “fooled” into healing itself
6
Q
What must usually happen for a drug to reach the site where their effect is needed?
A
- absorbed into the bloodstream
7
Q
What are the four main methods of administering a drug?
A
- oral, by mouth
- inhalation
- rectal, through the anus
- parenteral, injection
8
Q
Why are drugs sometimes applied topically?
A
- so that the effect is limited mainly to the site of the disorder such as the surface of the skin
- may come in the forms of creams, ointments, sprays and drops
9
Q
What is the therapeutic window?
A
- the range of dosages between the minimum amounts of the drug that produce the desired effect and a medically unacceptable adverse effect
10
Q
How does drug tolerance occur?
A
- the body adapts to the action of the drug
11
Q
What is the danger of drug tolerance?
A
- as the dose increases so do the risks of dependence and the possibility of reaching the lethal dose
12
Q
What is addiction (/substance dependence)?
A
- reducing or stopping the drug causes withdrawal symptoms
13
Q
What is bioavailability?
A
- the fraction of the administered dosage that reaches the target part of the human body
14
Q
What are examples that affect bioavailability?
A
- polarity of the drug
- types of functional groups present in the drug
- method of administration
15
Q
What is an analgesic?
A
- pain killer
16
Q
What is an antipyretic?
A
- fever depressent
17
Q
What is the ethanoate ester of salicylic acid?
A
- Aspirin
18
Q
How is Aspirin thought to work?
A
- preventing a particular enzyme, prostaglandin synthase, being formed at the site of the injury or pain
19
Q
What else can Aspirin be used for except for pain?
A
- prevents blood clotting
20
Q
What is the most common side effect of Aspirin and how is this effect increased?
A
- causes bleeding in the lining of the stomach
- this effect is increased by taking aspirin with alcohol as alcohol has a synergistic effect
21
Q
Why can Aspirin be fatal when exceeding the safe dose?
A
- the salicylic acid leads to acidosis due to a lowering of the pH of the blood
22
Q
Why is Paracetamol often preferred to Aspirin?
A
- its side-effects are less problematic
23
Q
How is a good yield of Aspirin obtained?
A
- salicylic acid is reacted with ethanoic anhydride in the presence of an acid catalyst
24
Q
How can Aspirin’s solubility be increased?
A
- by reacting it with sodium hydroxide to turn it into an ionic salt
25
Why is Aspirin slightly polar?
- due to the carboxylic acid group it is not very soluble in water
26
Where does original penicillin occur?
- in mould
27
Where does original penicillin occur?
- in a mould
28
How does Penicillin work?
- by preventing bacteria from making normal cell walls
29
How do strong analgesics work?
- work by interacting temporarily with receptor sites in the brain without depressing the central nervous system, with the results that pain signals within the brain and spinal cord are blocked
30
What are the most important naturally occurring strong analgesics and what are they known as?
- morphine and codeine found in the opium poppy
| - known as opiates or narcotics
31
What is diamorphine (/heroin)?
- more powerful painkiller than morphine but also more addictive
32
What do all opiates do?
- all cause addiction and also lead to tolerance
33
What are short-term effects of opiates?
- induce a feeling of euphoria
- dulling of pain
- depress nervous system
- slow breathing and heart rate
- cough reflex inhibited
- nausea and vomiting
- high doses lead to coma and/or death
34
What are long-term effects of opiates?
- constipation
- loss of sex drive
- disrupts menstrual cycle
- poor eating habits
- risk of AIDS, hepatitis, etc. through shared needles
- social problems, e.g. theft, prostitution
35
Why does heroin produce a much greater feeling of euphoria than morphine?
- difference in polarity of the two substances
| - heroin is much more soluble in lipids that are non-polar
36
What are antacids used for?
- to reduce excess stomach acid
37
How to antacids work?
- work in a non-specific way by neutralising the acid, preventing inflammation, relieving pain and discomfort and allow the mucus layer and stomach lining to mend
38
What are active metabolites?
- the active form of the drug after it has been processed by the body
39
What are the most common side-effects of antacids?
- belching to release gas
- diarrhoea
- constipation
40
What are proton pump inhibitors (PPIs)?
- used to suppress acid secretion in the stomach
| - cause a long-lasting reduction of gastric acid production
41
What are buffer solutions?
- resist changes in pH when small amounts of acid or alkali are added to them
42
How can an acid buffer solution be made?
- by mixing a weak acid together with the salt of that acid and a strong base
43
How can an alkali buffer with a fixed pH greater than 7 be made?
- a weak base together with the salt of that base with a strong acid
44
What are bacteria?
- single cell organisms
45
Why are viruses smaller than bacteria?
- they have no nucleus or cytoplasm
46
What are the two main ways in which antiviral drugs work?
- by altering the cell's genetic material so that the virus cannot use it to multiply
- by blocking enzyme activity within the host cell so that the virus cannot multiply or is prevented from leaving the cell
47
What is one of the problems with developing antiviral drugs?
- the viruses themselves are regularly mutating
48
What is oseltamivir (/Tamiflu)?
- an antiviral drug
| - an ester
49
How does oseltamivir work?
- in the liver, is hydrolysed to its carboxylate anion which inhibits the viral neuramindase and prevents it from acting on sialic acid, an acid found on the proteins on the surface of the host cells
50
What is zanamivir (/Relenza)?
- an antiviral drug
51
Why is zanamivir much more soluble than oseltamivir?
- contains many polar hydroxyl and amine groups together with a carboxylic acid group
52
What are some common viral infections?
- common cold
- influenza
- childhood diseases such as mumps and chicken pox
53
Through what is AIDS caused?
- caused by a retrovirus
| - it contains RNA rather than DNA
54
What does AIDS do?
- virus invades certain types of cells, particularly the white blood cells that normally activate other cells in the immune system with the result that the body is unable to fight infection
- once it invades a host cell it makes viral-DNA from the RNA template using an enzyme called reverse transcriptase
55
What is AZT (/zidovudine)?
- a reverse-transcriptase inhibitor that combines with the enzyme that the HIV virus uses to build DNA from RNA and inhibits its active site
56
Into what can radioactive waste be divided into?
- high-level waste (HLW)
| - low-level waste (LLW)
57
What does Low-level waste (LLW) include?
- rubber gloves
- paper towels
- protective clothing that have been used in areas where radioactive materials are handled
58
What are the properties of low-level waste?
- level of activity is low
| - half-lives of the radioactive isotopes are generally short
59
What are the properties of high-level waste?
- high activity
| - isotopes generally have long half-lives so the waste will remain active for a long period
60
Where does antibiotic waste come from?
- disposal of unused antibiotics through urine of people who are on antibiotics and from animals where the feedstock contains antibiotics, which often gets discharged intro rivers
61
What could antibiotic waste cause?
- microorganisms in water or soil to take up waste antibiotics
- bacteria in the organisms can become resistant to antibiotics
- if these bacteria find their way into drinking water or food, they then make antibiotics much less effective when they are required to fight disease
62
What is green chemistry (/sustainable chemistry)?
- aims to reduce harm to the environment by minimising the use and generation of hazardous substances in the first place
- aims to reduce the pollution at its source and to conserve natural resources including energy
63
What is the environmental-factor (/E-factor)?
- the mass of the total waste products divided by the mass of the desired product
- E = (total waste)/product
64
What are important factors when designing and producing new drugs?
- aiming for a high atom economy and a low environmental factor
- number of steps in a synthesis should be kept to a minimum
- use greener and safer solvents and reactants
65
What is the atom economy?
- the ratio of the total mass of the desired product(s) to the total mass of all the products
66
What is carbon efficiency?
- carbon efficiency = (amount of carbon in product)/(total amount of carbon present in reactants)
67
What is an example of green chemistry in practice?
- the development of the influenza drug Tamiflu (oseltamivir)
- one green hope is that instead of using a starting material called shikimic acid, which is currently uneconomical to synthesise and is isolated from the Chinese star anise plant, is to obtain it by bioengineering using fermenting bacteria
68
What is Taxol (/Paclitaxel) used for?
- used to treat ovarian, breast and lung cancer
| - is injected as a colourless fluid as part of chemotherapy treatment
69
How does Taxol work?
- works by preventing cancer cells from dividing and replicating
70
In what does Taxol occur
- the Pacific yew tree
71
What was a concern when Taxol was established as an effective anti-cancer drug?
- the damage being done to the yew tree population as the amount of bark required to make even small amounts of the drug is considerable and stripping the bark kills the trees
72
What route was initially found for producing Taxol?
- a semi-synthetic route was found for starting from a compound found in the needles of a related yew tree
73
What route was more recently found for producing Taxol?
- total synthesis from crude-oil based reagents has been achieved, but the process is not very green
74
Where is most of the commercially available taxol obtained from?
- semi-synthetic route
| - plant cell fermentation (PCF) technology, which uses much less energy and less hazardous chemicals
75
What is the difficulty with the synthesis of taxol?
- that it contains no fewer than 11 separate chiral carbon atoms
- this means that there is a very large number of possible enantioners and diastereoisomers of which only one corresponds to taxol itself with the correct R or S configuration on each of the 11 chiral carbon atoms
76
What does the traditional synthesis of an optically active compound normally produce?
- a racemic mixture (50:50 mixture) of the two enantiomers, which then has to be separated into the two isomers by using chromatography together with another optically active compound
77
What would happen if traditional synthesis was used to make taxol?
- the yield of the correct enantiomer would be very small
78
What does a recent technique use that makes it possible to synthesise just the desired isomer when making taxol?
- chiral auxiliaries
79
How does the recent technique of attaching an auxiliary to a starting material work?
- attaching an auxiliary, which is itself optically active, to the starting material creates the stereochemical conditions necessary for he reaction to form only one enantiomer, i.e. asymmetrically to form just the required isomer
- after the desired product has been formed the auxiliary is removed and recycled
