Aspirin is thought to interfere with the production of prostaglandins. Explain how this produces an analgesic effect.

Explain how morphine can prevent pain.

Paracetamol (acetaminophen) is generally considered to be safe to use as an analgesic in small doses. Other than the possibility of death, outline the problems associated with taking larger doses of paracetamol.

State one important use for aspirin other than the relief of pain and fever.

Explain what is meant by the term tolerance and suggest why this is a particular problem for heroin users.

prostaglandins are involved in the transmission of pain impulses (to the brain) / OWTTE;

morphine (temporarily) bonds to/inhibits receptor sites in the brain (without depressing central nervous system) / OWTTE;

causes blood disorders;

causes damage to kidney;

causes damage to liver;

causes damage to brain;

preventing (recurrence of) heart attacks/strokes / reduces blood clotting / thins the blood / anti-inflammatory;

tolerance: more of the drug needs to be taken to achieve the initial effect / OWTTE;

in order to achieve the desired effect heroin users may reach/exceed the lethal dose / heroin users are more likely to commit crimes to pay for gradually increasing doses of the drug / OWTTE;

This question was generally answered very well compared with other sections of the paper. In part (a) most candidates knew that prostaglandins is involved in the transmission of pain impulses to the brain.

In part (b) there was some confusion between signals and receptors when describing how morphine can prevent pain.

In part (c) most candidates could outline problems associated with larger doses of paracetamol (acetaminophen), although some candidates confused aspirin and paracetamol and incorrectly referred to Reye’s syndrome or stomach bleeding.

Most candidates stated a use for aspirin other than relief of pain or fever in part (d).

In part (f) most candidates successfully stated the meaning of tolerance and suggested why it is a particular problem for heroin users.