| Date | May 2015 | Marks available | 1 | Reference code | 15M.3.sl.TZ2.14 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Suggest | Question number | 14 | Adapted from | N/A |
Question
Drug research and development is a lengthy and expensive process. Testing is required to determine the therapeutic window, tolerance and side-effects of a drug before it can be approved for use.
State the meaning of the term therapeutic window.
Suggest why a narrow therapeutic window may be a problem.
State the meaning of the term side-effects.
Markscheme
range of dosages/concentrations of drug (able to treat disease successfully) staying within safety limit / between effective/ED50 and toxic levels/LD50;
Do not accept definition of therapeutic index (ratio of LD50/TD50 to ED50).
Accept “lethal levels” for “toxic levels” even if laboratory animals are not referred to.
toxic levels are easily reached / effective dose not given for fear of reaching toxic level / close medical supervision required;
Accept “lethal levels” for “toxic levels”.
adverse effects of drug / physiological/psychological effect other than that for which the drug was prescribed / secondary (undesired) effects of drug / OWTTE;
Examiners report
Many candidates confused the definition of “therapeutic window” with “therapeutic index”. The nature of a narrow therapeutic window was also not well understood although the nature of side-effects was well articulated. The role of dimethicone as an anti-foaming agent was well understood overall. It was correctly identified as an anti-foaming agent where small bubbles are converted into larger ones and then released. This decreases "bloating" and increases rather than decreases "flatulence" which was seen quite often as a response in the use of dimethicone.
Many candidates confused the definition of “therapeutic window” with “therapeutic index”. The nature of a narrow therapeutic window was also not well understood although the nature of side-effects was well articulated. The role of dimethicone as an anti-foaming agent was well understood overall. It was correctly identified as an anti-foaming agent where small bubbles are converted into larger ones and then released. This decreases "bloating" and increases rather than decreases "flatulence" which was seen quite often as a response in the use of dimethicone.
Many candidates confused the definition of “therapeutic window” with “therapeutic index”. The nature of a narrow therapeutic window was also not well understood although the nature of side-effects was well articulated. The role of dimethicone as an anti-foaming agent was well understood overall. It was correctly identified as an anti-foaming agent where small bubbles are converted into larger ones and then released. This decreases "bloating" and increases rather than decreases "flatulence" which was seen quite often as a response in the use of dimethicone.
