Option D - Medicinal Chemistry

Front 1

List 7 methods of drug adminstration

Back 1

1. Oral

2. Rectal

3. Subcutaneous

4. Intravenous

5. Intramuscular

6. Transdermal

7. Pulmonary

Front 2

Define therapeutic effect

Back 2

Desired biological change that cures or alleviates illness, caused by a drug .

Front 3

Define a placebo and describe the placebo effect

Back 3

A biologically inert substance that assists the body's natural healing process.

The therapeutic effect of a placebo is the placebo effect.

Front 4

Define double-blind test

Back 4

Drug trial where neither the researchers directly observing the patients nor the patients themselves know who is given the real drug or placebo.

Front 5

Define side-effect

Back 5

Unwanted effects of a drug that do not contribute to the therapeutic effect.

Front 6

Define TI

Back 6

Therapeutic index.

The ratio between toxic / lethal dose and effective dose.

TI = TD50 / ED50

The greater the TI, the safer the drug.

Front 7

Define TD50

Back 7

Toxic Dose

The dosage of drug that causes a toxic effect in 50% of test subjects

Front 8

Define LD50

Back 8

Lethal Dose

The dosage of drug that kills 50% of test subjects

Front 9

Define ED50

Back 9

Effective Dose

The dosage of drug that causes therapeutic effect in 50% of test subjects

Front 10

Define therapeutic window

Back 10

The range of drug doses that causes therapeutic effects.

Defined by minimum drug dosage required to cause therapeutic effect, and minimum dosage required to cause toxic effects.

Front 11

Define drug availability

Back 11

The fraction of administered drug absorbed into bloodstream

Front 12

Define drug tolerance

Back 12

The progressively high drug doses users require to obtain the same therapeutic effects.

Front 13

Define drug addiction

Back 13

Compulsive desire of the user to take a drug regardless of the adverse effects it might cause.

Front 14

Outline drug action

Back 14

Drugs interect with enzymes or cell receptors. Drugs are often inhibitors.

Front 15

Outline the stages of drug development

Back 15

1. Drug discovery

- identification of lead compound

- New chemical entity (NCE)

2. Drug design

- Alternative / complementary approach to find lead compound

3. Pre-clinical trials

- similar compounds to lead compound are synthesised

- most effective, safe, and accessible compound selected for clinical trials

4. Clinical trails

Drug is tested on humans, in a double-blind experiment.

Phase I

Small number of healthy volunteers are tested for TD50 and side effects

Phase II

Small number of patients are tested for ED50 and side effects

Phase III

Large number of patients are tested to comparee with other drugs. Further data on effectiveness and side effects.

5. Post-clinical studies / Phase IV

Long term study

Front 16

Outline the synthsis of aspirin

Back 16

1. Salicyclic acid is isolated from willow bark

2. Salicyclic acid is reacted with ethanoic anhydride to form aspirin and ethanoic acid (addition-elimination reaction)

Front 17

Explain the effects of aspirin

Back 17

1. Mild analgesic

2. Antipyretic

3. Anticoagulent

4. Non-narcotic analgesic

5. Non-steroidal anti-inflammatory drug (NSAID)

- supresses prostaglandin production

- in turn decreases thromboxin production

Front 18

List the risk of taking aspirin

Back 18

Stomach ulceration

- aspirin synergises with ethanol and other anticoagulants

Front 19

Explain how aspirin's bioavailability is increased

Back 19

1. Aspirin is almost insoluble in water

2. Asirin is converted to a salt (using NaOH)

Front 20

Outline the mechanism of action of penicillin

Back 20

- 90 degree bond angles in beta-lactam ring creates ring strain

- penicillin reacts with transpeptidase, weakening cellulose cross-linkages in bacterial cell walls

- osmotic pressure within bacteria during mitosis causes lysis

Front 21

Explain why morphine has difficulty crossing the blood-brain barrier, and how the barrier can be overcome

Back 21

Morphine has 1 amino and 2 hydroxyl groups, causing it to be polar, so has difficulty crossing the lipophilic cell membranes that coat blood vessels.

A OH group in morphine is replaced with a OCH3 to form codeine, which is less polar, and is therefore more bioavailable.

Both OH groups in morphine are replaced with OCOCH3 (ester) groups, forming diamorphine with reduced polarity.

Front 22

State the function of antacids and provide an example

Back 22

Antacids react with HCl in gastric juice, increasing pH.

Aluminium hydroxide

Calcium carbonate

Sodium Hydrogen Carbonate

Front 23

Explain how gastric acid is produced int he stomach, and give example of drugs that prevent pH from becoming too low

Back 23

Acid secretion in stomach occurs when histamine binds to H2-histamine receptors on gastric lining cells. H+ ions are actively pumped into stomach by the gastric proton pump.

Drug rantidine is a H2-receptor antagonist (temporary)

Drugs omeprazole and esomeprazole are gastric proton pump inhibitors, and reduce H+ production (prolonged inhibition)

Front 24

Explain the acid-base buffer system in the human body

Back 24

Front 25

Briefly outline the 4 different mechanisms in which antiviral drugs act on viruses

Back 25

1. Prevents virus from attaching to host cell surface

2. Prevents viral uncoating, so viral genetic material cannot be injected into host cell

3. Inihibits reverse transcriptase, so viral genetic material is not replicated

4. Inhibits the release of viruses from host cell after reproduction

Front 26

Outline how amantadine and rimantadine are effective antiviral drugs

Back 26

Both drugs inhibit the uncoating of virus strains, so they cannot inject genetic material into host cell.

Front 27

Outline how acyclovir and zidovudine are effective antiviral drugs

Back 27

Both drugs undergo phosphorylation in the host cell and produce non-standard nucleotides, which are incorporated into DNA. Enzymes formed by the DNA is inactive and cannot replicate viral components.

Front 28

Outline how oseltamivir and zanamivir are effective antiviral drugs

Back 28

Both drugs inhibit enzymes neuraminidases, which trigger viral budding, trapping viruses within host cell.

Front 29

Define HIV.

Back 29

Human Immunodeficiency Virus

Type of virus that causes Acquired Immunodeficiency Sydrome.

Front 30

Define AIDS

Back 30

Acquired Immunodeficiency Syndrome

Progressive failure of the immune system, may lead to life-threatening infections.

Front 31

Explain how zidovudine is an effective drug for HIV

Back 31

Drug inhibits reverse transcriptase enzymes.

Front 32

List 5 reasons that caused increase in antibiotic resistance over time

Back 32

1. Over-prescription of antibiotics

2. Non-compliance of patients in finishing antibiotic course

3. Use of antibacterials in agriculture

4. Release of antibacterial waste by hospitals and pharmaceutical industry

5. Bacteria replicate at a very fast rate, and may develop resistance (e.g. penicillinase) due to mutations

Front 33

Explain how LLW are disposed of and give examples of LLWs

Back 33

Low-Level Waste have short half-lives, and are stored in shielded containers until radiation level drops below safe limit, then stored in underground repositories.

Examples of LLWs are Co-60 and Cs-137

Front 34

Explain how HLW are disposed of.

Back 34

High-Level Waste have long half-lives and produce much heat due to nuclear reactions. They are cooled using water, and are either vitrified or converted to synthetic rock, and stored in underground repositories.

Front 35

List 3 organic solvents and outline the risks of using them.

Back 35

1. Benzene

2. Chloroform

3. Ethanol

1. Benzene and Chloroform increase risk of cancer

2. Many organic solvents are flammable (ethanol)

Front 36

List 3 different chlorinated solvents, and explain how they negatively impact the environment.

Back 36

1. Carbon tetrachloride

2. Chloroform

3. Dichloromethane

1. Ozone-depleting agents

2. Non-biodegradable and accumulate in water bodies

Front 37

State the primary goal of green chemistry and outline how it is achieved.

Back 37

Reduce the environmental impact of technological processes by minimizing the use and generation of hazardous chemicals.

1. Aqueous / solvent-free reactions

2. Renewable starting materials

3. Mild reaction conditions

4. Ultilization of by-products

5. Increase atom economy

6. Decrease number of reaction steps

Front 38

Give and example of the impact of biotechnology on green chemistry

Back 38

Shikimic acid is a precursor to oseltamivir. Its extracted from Chinese star anise was a year-long process. It also produced unsafe lithium hydride. Biotechnology allowed Shikimic acid production at an industrial scale through genetically modified E. coli.

Front 39

Taxol

Back 39

- Extracted from pacific yew tree

Front 40

Docetaxol

Back 40

- More active than Taxol

- More water soluble

Front 41

Explain the mechanism of chiral auxillaries

Back 41

Front 42

Define prophylactic

Back 42

A drug taken for preventative healthcare, to prevent an illness from occuring.

Front 43

Briefly explain how aspirins in purified

Back 43

1. Aspirin is dissolved in hot solvent (ethyl ethanoate / ethanol) to form a near-saturated solution

2. Insoluble impurities are removed through vacuum filtration

3. Solution is allowed to cool. Bottom of flask may be scratched to initiate crystallization.

4. Steps 1-3 are repeated for higher purity.

Front 44

How is the purity of aspirin determined?

Back 44

1. Gas chromatography

2. Melting point

3. Infrared spectrum

Front 45

Briefly explain how opiates are strong analgesics.

Back 45

Opiates such as morphine and codeine bind to opioid receptors in the brain, blocking pain signals from reaching the brain.

Front 46

Explain how dependence on opiates can be managed

Back 46

1. Gradual reduction of opiate dosage

2. Prescription of methadone, which binds to opioid receptors for prolonged period of time

Front 47

Define indigestion

Back 47

The irritation of stomach lining due to excess acid, producing pain or discomfort in upper abdomen

Front 48

Define heartburn (acid reflux).

Back 48

The rising of stomach acid into oesophagus, causing a burning sensation.

Front 49

Define peptic ulcer

Back 49

Erosion of gut lining caused by acid penetrating mucous layer.

Front 50

Explain the therapeutic effects omeprazole

Back 50

Omeprazole is a gastric proton pump inhibitor. it prevents H+ ions from being actively pumped into stomach cavity.

Front 51

Explain the therapeutic effects of esomeprazole

Back 51

Esomeprazole is a gastric proton pump inhibitor. it prevents H+ ions from being actively pumped into stomach cavity.

Front 52

Explain the therapeutic effects of rantidine

Back 52

Rantidine is a H2-receptor antagonist, and prevents histamine from binding to receptors on stomach cells, and so H+ ions are not produced.

Front 53

State the function of hemagglutinin (HA).

Back 53

Hemagglutinin allows viruses to bind to host cell surface receptors. It binds to sialic acid residues on glycoproteins.

Front 54

State the function of neuraminidase (NA).

Back 54

Neuraminidase is an enzyme that hydrolyses (breaks) the bond between sialic acid residue and glycoprotein.

Front 55

Explain how paclitaxel is an effective drug

Back 55

Paclitaxel is used during chemotherapy as it bind to microtubules in cells, preventing cell division from occuring completely.

Front 56

Explain how enantiomers can be distinguished from one another.

Back 56

1. A polarimeter can be calibrated with pure solvent

2. First enantiomer is placed into polarimeter, and polarising filter is rotated until its light is parallel to the enantiomer

3. The same is performed with second enantiomer

4. Direction and angle in which polarised light rotate is recorded

Front 57

Give an example of alpha-decay.

Back 57

226,88,Ra -> 222,86,Rn + 4,2,He

Front 58

Give an example of beta-decay.

Back 58

12,5,B -> 11,6,C + 0,-1,e

Front 59

Define half-life

Back 59

The time required for the number of radioactive nuclei present in a sample at any given time to fall to half its values.

Front 60

1st Rate equation for radioactive decay

Back 60

A = lamda x N

A: Activity / becquerel (Bq)

lamda: decay constant

N: Number of nuclei present

Parallel to rate equation:

rate = k [X]

Front 61

2nd Rate equation for radioactive decay

Back 61

N = No e^(-lamda t)

No: Initial number of undecayed nuclei

N: Number of undecayed nuclei at time t

lamda: Decay constant

Front 62

Name 2 radioisotopes used in medicinal tracing

Back 62

technium-99 emits gamma rays

flourine-18 emits beta particles

Front 63

Briefly outline how ionizing radiation can harm the body

Back 63

Ionizing radiation cause direct ionization of DNA, changing their structure.

It can also cause formation of free radicles (H2O -> H. + OH.), which interacts with DNA, damaging it.

Front 64

Outline the difference in functional groups between morphine, codeine and diamorphine

Back 64

Morphine: Two OH groups

Codeine: One OH, one OCH3

Diamorphine: Two OCOCH3

Front 65

Discuss difficulties in solving AIDS

Back 65

1. HIV mutates quickly

2. Contraception is not practised in many situations

3. Stigma and discrimination against HIV patients deter treatment

4. Lack of government support and funding in healthcare

5. Health literacy rates are low

Front 66

Explain why technium-99 is a common isotope in nuclear medicine

Back 66

1. Technium-99 releases photons with X-ray wavelength, and can be detected easily

2. Emitted photons have low energy, and is therefore safe

3. Readily forms complexes with ligands, and can be injected into body

Front 67

Outline why yttrium-90 is a common radioisotope in nuclear medicine

Back 67

Emits beta particles

Front 68

Outline why lutettium-177 is a common radioisotope in nuclear medicine

Back 68

Emits both beta and gamma particles.

Short penetration length.

Front 69

State the chemical changes within a breathalyzer

Back 69

Potassium dichromate

Orange (anhydrous)

Green (hydrated)