Date | May 2009 | Marks available | 1 | Reference code | 09M.3.sl.TZ1.D2 |
Level | SL | Paper | 3 | Time zone | TZ1 |
Command term | Explain | Question number | D2 | Adapted from | N/A |
Question
Medicines and drugs alter the physiological state of the body including consciousness and coordination.
Explain the meaning of the following terms:
State one other effect of medicines and drugs on the body.
therapeutic window.
tolerance.
Outline the major stages in the development of a new drug.
Markscheme
alters incoming sensory sensations / alters mood or emotions;
the range over which a drug can be safely administered / \({\text{T.I}} = \frac{{{\text{LD50}}}}{{{\text{ED50}}}}\) / ratio of the lethal dose for 50%population and the effective dose for 50% of population;
person needs to take ever larger quantities of a drug to gain the original effect;
drug is isolated from existing species / synthesized in the laboratory;
tested on animals to establish LD50;
tested on humans and half/some of the group is given a placebo;
Examiners report
Many candidates had difficulty explaining the term therapeutic window. Frequently they thought it referred to the time the drug was active in the body rather than an issue of dosage.
Many candidates had difficulty explaining the term therapeutic window. Frequently they thought it referred to the time the drug was active in the body rather than an issue of dosage. They fared better with explaining the terms tolerance and the placebo effect.
Candidates had more difficulty providing specific information about the drug development process, especially with respect to animal testing and human testing. Candidates needed to use accurate chemical terms when outlining the major stages in the development of a new drug.