Developing new medicines

Statins are a type of medicine used to treat cardiovascular disease.

Some people taking statins have reported muscle pain as a side effect.

Scientists analysed data from double‑blind trials to determine if there was a correlation between statin use and muscle pain.

In these double‑blind trials, neither doctors nor patients knew whether the patient had been given statins or not.

Describe the benefits of using double‑blind trials.

Which stage of the process for testing new medicines could involve a double‑blind trial?

In a study, people were given statins or a placebo.

The percentage of people who reported muscle pain was recorded.

Figure 10 shows the results of this study.

In year one, 9 199 people taking statins reported muscle pain.

Calculate the total number of people taking statins in this study.

Give your answer to 4 significant figures.

The scientists concluded that most of the muscle pain reported was not due to the use of statins.

Explain, using information from the table in Figure 10, why the scientists made this conclusion.

The results of the study are reliable because the data was obtained from a large sample of people.

Describe two factors that should have been considered when selecting people for the study.

In 2017, a new strain of Klebsiella pneumoniae bacteria was discovered that was resistant to 26 different antibiotics.

Explain how Klebsiella pneumoniae bacteria developed resistance to antibiotics.

State how the use of antibiotics could contribute to Klebsiella pneumoniae bacteria developing resistance to antibiotics.

Klebsiella pneumoniae is a prokaryotic cell.

Which is a characteristic feature of a prokaryotic cell?

New antibiotics are being developed to treat the disease caused by Klebsiella pneumoniae.

Describe the stages of antibiotic development that would occur after the discovery of a new antibiotic.

10 Streptococcus mutans is one species of bacteria which causes tooth decay. A scientist tested the effectiveness of toothpaste at killing this species of bacteria. The scientist spread the bacteria Streptococcus mutans across an agar jelly plate.

(a) (i) Which word describes the techniques used to prevent contamination of the agar jelly plate?

(ii) Give two precautions needed to prevent contamination of the agar jelly plate.

(b) The scientist placed a filter paper disc soaked in toothpaste mixed with saliva (disc A) on one half of the agar jelly plate. A filter paper disc soaked in only saliva (disc B) was placed on the other half of the agar jelly plate. The agar jelly plate was kept at 37°C for 24 hours. Figure 20 shows the results.

Figure 20

(i) The diameter of the zone of inhibition around disc A is 9 mm. Calculate the area of this zone of inhibition using the equation πr². Use a value of 3.14 for π. Give your answer to 1 decimal place.

(ii) Give a reason why disc B, soaked in only saliva, was included in this test.

(iii) Suggest two reasons why this test does not prove that toothpaste kills all bacteria on teeth.

(c) Before a new toothpaste can be sold, the toothpaste has to be tested on cultured human cells. Cultured human cells were placed into four identical flasks. Saliva was added to each flask and a different brand of toothpaste was added to each of three flasks. The human cells were left for two hours and the percentage of cells that were healthy was recorded. Figure 21 shows the results.

Figure 21

Explain the conclusion that can be made from this data.

4 Streptococcus mutans is one species of bacteria which causes tooth decay. A scientist tested the effectiveness of toothpaste at killing this species of bacteria. The scientist spread the bacteria Streptococcus mutans across an agar jelly plate.

(a) (i) Which word describes the techniques used to prevent contamination of the agar jelly plate?

(ii) Give two precautions needed to prevent contamination of the agar jelly plate.

(b) The scientist placed a filter paper disc soaked in toothpaste mixed with saliva (disc A) on one half of the agar jelly plate. A filter paper disc soaked in only saliva (disc B) was placed on the other half of the agar jelly plate. The agar jelly plate was kept at 37°C for 24 hours. Figure 5 shows the results.

(i) The diameter of the zone of inhibition around disc A is 9 mm. Calculate the area of this zone of inhibition using the equation πr². Use a value of 3.14 for π. Give your answer to 1 decimal place.

(ii) Give a reason why disc B, soaked in only saliva, was included in this test.

(iii) Suggest two reasons why this test does not prove that toothpaste kills all bacteria on teeth.

(c) Before a new toothpaste can be sold, the toothpaste has to be tested on cultured human cells. Cultured human cells were placed into four identical flasks. Saliva was added to each flask and a different brand of toothpaste was added to each of three flasks. The human cells were left for two hours and the percentage of cells that were healthy was recorded. Figure 6 shows the results.

Explain the conclusion that can be made from this data.

Streptococcus bacteria can cause a sore throat or skin infection.

An illness called scarlet fever can also develop during an infection with this bacterium.

Give two precautions a doctor should take when treating a patient who is infected with Streptococcus.

From September 2013 to March 2014 there were 2 830 cases of scarlet fever in the UK.

From September 2014 to March 2015 there were 5 943 cases of scarlet fever.

Calculate the percentage increase of the number of cases of scarlet fever between the periods September 2014 to March 2015 and September 2013 to March 2014.

Figure 10 shows some Streptococcus bacteria.

Some bacteria are motile, meaning they can move themselves.

Why is a Streptococcus bacterium not motile?

Patients with scarlet fever can be treated with antibiotics.

New antibiotics need to be tested before they can be used in patients.

Which is the correct sequence for the development of a new medicine?

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cultured cells
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Most cases of scarlet fever occur in children.

Adults have usually developed immunity to a toxin that the Streptococcus bacteria produce during infection.

Explain how an adult develops immunity to the toxin.