Diamorphine (heroin) is an even stronger painkiller than codeine. The structures of codeine and diamorphine are given in Table 20 of the Data Booklet. Discuss, in terms of named functional groups, how the structure of diamorphine differs from the structure of codeine.

A normal aspirin tablet taken to relieve pain contains about 300 mg of aspirin. Certain adults who are not in pain are recommended by doctors to take a smaller 75 mg dose of aspirin each day. State one reason for this recommendation.

codeine contains a hydroxyl group;

Allow alcohol/hydroxy but not hydroxide.

codeine contains one methoxy group/two ether groups;

Allow codeine contains one additional ether group but not codeine contains the ether group.

diamorphine contains ester/acetoxy/ethanoate group(s);

Names required not functional group formulas.

Allow acetyl group.

prevents (the recurrence of) heart attack/stroke / reduces ability of blood to clot;

Majority of the candidates were familiar with the mode of action of mild and strong analgesics in part (a) however, there was some inaccurate use of the terminology. There was some confusion about signal interception and transmitting signals. For example, some candidates talked about prostaglandins released at the source and reducing pain perception in the brain. Most candidates answered the part (b) correctly; a few did not use functional group names but used bonds or diagrams instead. Many candidates missed stating two ether groups and were not able to score the third mark. The majority of candidates stated correct advantages and disadvantages of paracetamol over aspirin in part (b). Part (c) was well answered by the majority of candidates; some gave the only reason as aspirin thins blood and lost the mark; almost all candidates were able to provide one reason for answer to part (d) correctly. Many candidates missed to identify both, codeine as a strong analgesic and addictive, and did not score the mark.

Majority of the candidates were familiar with the mode of action of mild and strong analgesics in part (a) however, there was some inaccurate use of the terminology. There was some confusion about signal interception and transmitting signals. For example, some candidates talked about prostaglandins released at the source and reducing pain perception in the brain. Most candidates answered the part (b) correctly; a few did not use functional group names but used bonds or diagrams instead. Many candidates missed stating two ether groups and were not able to score the third mark. The majority of candidates stated correct advantages and disadvantages of paracetamol over aspirin in part (b). Part (c) was well answered by the majority of candidates; some gave the only reason as aspirin thins blood and lost the mark; almost all candidates were able to provide one reason for answer to part (d) correctly. Many candidates missed to identify both, codeine as a strong analgesic and addictive, and did not score the mark.