# A student is researching the history of medicines. They discover that for centuries, people chewed the leaves of the coca plant to reduce hunger and tiredness. Later, scientists isolated cocaine from the plant and used it as a local anaesthetic. Today, cocaine is no longer used as a medicine and has been replaced by safer synthetic drugs such as lidocaine. Explain why cocaine is no longer used as a medicine and describe the advantages of using synthetic drugs instead of plant extracts.

> OCR A-Level Chemistry B: Salters (H433) — WM What's in a medicine? · Explain · 5 marks

> For centuries, indigenous peoples of South America chewed coca leaves for their stimulant effects. In the 19th century, cocaine was isolated from coca leaves and used medically as a local anaesthetic. It has since been replaced by synthetic local anaesthetics.

## Mark scheme (5 marks)

1. Cocaine has harmful side effects / is addictive / is toxic
2. Medicines must be safe to use / must be tested for safety before being approved
3. Synthetic drugs can be made in a laboratory / manufactured on a large scale
4. Synthetic drugs can be designed / modified to reduce side effects or increase effectiveness
5. Synthetic drugs give a purer / more consistent product compared to plant extracts

## Key terms

- [synthetic drug](https://www.gradenine.co.uk/glossary/synthetic-drug)
- [plant extract](https://www.gradenine.co.uk/glossary/plant-extract)
- [medicine](https://www.gradenine.co.uk/glossary/medicine)

## Related

- [Revision notes for OCR A-Level Chemistry B: Salters (H433)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-is-researching-the-history-7a341f38) · Published by Druglandscape Ltd.