Aspirin is often taken to reduce pain, swelling or fever. State one other use of aspirin.

State what is meant by the bioavailability of a drug.

Outline how the bioavailability of aspirin may be increased.

Compare and contrast the IR spectrum of aspirin with that of salicylic acid, using section 26 of the data booklet.

Describe how penicillin combats bacterial infections.

Outline two consequences of prescribing antibiotics such as penicillin unnecessarily.

State how penicillins may be modified to increase their effectiveness.

Morphine and codeine are strong analgesics. Outline how strong analgesics function.

Suggest one reason why codeine is more widely used than morphine as an analgesic.

Any one of:

anticoagulant

lower risk of heart attack/strokes

prevent recurrence of heart attack/stroke

prevents cancer of colon/oesophagus/stomach

Accept “prevents/reduces blood clots” OR “blood thinner”.

[1 mark]

fraction/proportion/percentage «of administered dosage» that reaches target «part of human body»

OR

fraction/ proportion/percentage «of administered dosage» that reaches blood «plasma»/systemic circulation

Accept “the ability of the drug to be absorbed by the body” OR “the extent to which the drug is absorbed by the body”.

Do not accept “the amount/quantity of the drug absorbed”.

[1 mark]

«intravenous» injection/IV

Accept “parenterally”.

Accept “react with alkali/NaOH” OR “convert to ionic form/salt”.

[1 mark]

One absorption found in both spectra:

Any one of:

1050–1410 cm^–1 «C–O in alcohols, esters, ethers»

1700–1750 cm^–1 «C=O in carboxylic acids, esters»

2500–3000 cm^–1 «O–H in carboxylic acids»

2850–3090 cm^–1 «C–H in alkanes, alkenes, arenes»

One absorption found in only one of the spectra:

3200–3600 cm^–1 «O–H in alcohols, phenols»

Award [1 max] if candidate states bonds (C=O in both, O–H in salicylic acid only) but doesn’t quote wavelength ranges.

Accept a second/additional absorption at 1700–1750 cm^–1 from the C=O in ester.

[2 marks]

Any two of:

ring is «sterically» strained

OR

ring breaks up/opens/reacts «easily»

OR

amide/amido group «in ring» is «highly» reactive

«irreversibly» binds/bonds to enzyme/transpeptidase

OR

inhibits enzyme/transpeptidase «in bacteria» that produces cell walls

OR

prevents cross-linking of bacterial cell walls

cells absorb water AND burst

OR

cells cannot reproduce

Award [1 max] for “interferes with cell wall production”.

Do not accept “cell membrane” instead of “cell wall”.

[2 marks]

Any two of:

leads to «bacterial» resistance/proportion of resistant bacteria increases

OR

leads to penicillinase-producing bacteria

damage to/contamination of bodies of water/ecosystems

destroys useful/beneficial bacteria

destroyed bacteria replaced by more harmful bacteria

Accept “endocrine disruptor”.

Do not accept “increased cost of developing antibiotics”.

[2 marks]

modify side chain

[1 mark]

temporarily bind to/block/interfere with receptor sites in brain

OR

prevent transmission of pain impulses within CNS/central nervous system

[1 mark]

codeine has a wider therapeutic window

Accept “codeine has lower activity” OR “codeine has lower risk of overdose” OR “codeine is less potent” OR “codeine has less side-effects”.

Do not accept “lower abuse potential for codeine” OR “less addictive «than morphine»” OR “codeine has a lower bioavailability” OR “available without prescription” OR “cheaper”.

[1 mark]