Discuss two advantages and two disadvantages of the medical use of morphine and its derivatives.

Advantages:

Disadvantages:

Explain the increased potency of diamorphine (heroin) compared to morphine.

Advantages:

Award [1 max] for any two of:

strong pain relief/strong analgesic

sedation / OWTTE

treatment of diarrhoea

relieve coughing

Disadvantages:

Award [1 max] for any two of:

addiction

tolerance

dependence

constipation

depresses respiratory drive

Accept “criminals/drug addicts might get access to strong analgesics intended for medical use” / OWTTE.

Award [1 max] if one advantage and one disadvantage are given.

molecule of diamorphine is less polar / polar hydroxyl/OH (groups) in morphine are replaced with less polar/non-polar groups in heroin / diamorphine contains two ester groups;

diamorphine is more fat/lipid soluble / OWTTE;

diamorphine more rapidly absorbed into the brain / (less polar molecules such as) diamorphine crosses the blood-brain barrier faster/more easily / diamorphine is more soluble in non-polar environment of the CNS/central nervous system than morphine / OWTTE;

Candidates needed to recognize that the question asks about the medical use of morphine and its derivatives. Although many candidates struggled to give two advantages most scored the mark for disadvantages. Part (b) was usually answered well except by the candidates who got it the wrong way round.

Candidates needed to recognize that the question asks about the medical use of morphine and its derivatives. Although many candidates struggled to give two advantages most scored the mark for disadvantages. Part (b) was usually answered well except by the candidates who got it the wrong way round.