| Date | May 2017 | Marks available | 1 | Reference code | 17M.3.sl.TZ1.18 |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Outline | Question number | 18 | Adapted from | N/A |
Question
Medicines have a variety of different effects on the body and act at the molecular level.
Morphine and codeine are strong analgesics. Their structures are given in section 37 of the data booklet.
Dose response curves are determined for each drug.
Outline the significance of range “a”.
Suggest the type of reaction used to convert morphine to codeine.
State and explain the action of opiates as painkillers.
Markscheme
«measures» therapeutic window/margin «of a drug»
OR
range of doses that produce a therapeutic effect without causing toxic effects
Accept “difference between ED50/minimum effective/therapeutic dose «for 50% of population» AND TD50 /toxic dose «for 50% of population»”.
Do not accept “therapeutic index”.
Do not accept “lethal/fatal dose” as this is not LD50.
[1 mark]
«nucleophilic» substitution/SN
Accept “methylation”.
[1 mark]
work directly on opioid/pain receptors «in brain»
suppress pain impulses in brain/CNS
resemble endorphins/enkephalins/natural chemical painkillers «produced in the brain and spinal cord»
Do not award mark for “resemble hormones”.
[2 marks]
Examiners report
Syllabus sections
- 17N.3.sl.TZ0.18b: State the method of drug administration that gives the maximum bioavailability.
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17M.3.sl.TZ2.15b.ii:
Compare, giving a reason, the bioavailability of soluble aspirin with aspirin.
-
20N.3.sl.TZ0.12:
Consider the following antacids:
Show that antacid X is more effective, per tablet, than antacid Y.
- 18N.3.sl.TZ0.12a: State the internal bond angles in the β-lactam ring and the expected bond angles for the same...
- 18N.3.sl.TZ0.13c: Outline the meaning of the bioavailability of a drug.
- 18N.3.hl.TZ0.17b: Outline the meaning of the bioavailability of a drug.
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18M.3.sl.TZ2.15:
Drug testing is necessary to determine safe and effective doses.
Distinguish between the lethal dose (LD50) and the toxic dose (TD50).
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19M.3.hl.TZ1.22b:
Suggest a reason for using a phosphate salt of oseltamivir in oral tablets.
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19M.3.sl.TZ1.17a(ii):
Suggest a reason for using a phosphate salt of oseltamivir in oral tablets.
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17M.3.sl.TZ2.18b:
Suggest one ethical consideration faced by medical researchers when developing medications.
- 19N.3.hl.TZ0.21b: Experimental research on both animals and humans contributes to the development...
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18M.3.sl.TZ1.13b.i:
State what is meant by the bioavailability of a drug.
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19M.3.hl.TZ2.21a:
Distinguish between therapeutic window and therapeutic index in humans.
Therapeutic window:
Therapeutic index:
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17N.3.sl.TZ0.18a:
Outline the difference between the therapeutic index in animal studies and the therapeutic index in humans.
-
19M.3.sl.TZ2.14a:
Distinguish between therapeutic window and therapeutic index in humans.
Therapeutic window:
Therapeutic index:
-
20N.3.sl.TZ0.11d:
Comment on the risk of overdose when taking aspirin as an analgesic, referring to the following values, for a person weighing :
Minimum therapeutic dose
Estimated minimum lethal dose
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20N.3.hl.TZ0.15d:
Comment on the risk of overdose when taking aspirin as an analgesic, referring to the following values, for a person weighing :
Minimum therapeutic dose
Estimated minimum lethal dose
