What’s in a medicine? Storylines WM1: The development of modern ideas about medicines

Useful definitions Pharmaceuticals Drugs Poison Pharmacology Pharmacy Complex compounds Active ingredients of medicines that alter the body’s chemistry. A drug which is not beneficial to the body. The study of drugs. The art and science of making and dispensing medicines.

WM1 The development of modern ideas about medicines. 1000s of years ago, medicines were used by ‘trial and error’; no-one knew how they ‘worked’. Today, molecular pharmacologists design drugs which have specific effects. >>> activity WM1 The origins and development of the modern pharmaceutical industry.

WM2 Medicines from nature. Modern pharmacy is based on herbal and folk remedies. Remedies from “old wives’ tales” are investigated to find the active ingredient. Doctrine of signatures: the idea that illnesses can be cured by plants which are associated with them. Eg dock leaves for stinging nettle stings.

Medicines from willow bark Old ‘Doctrine of signatures’ idea: marshy ground causes fevers. Willow trees grow there – so use them as the remedy! Hippocrates (400 BC) – willow leaf brew eases pain of childbirth. Edward Stone (1763) – willow bark reduces fevers.

Culpeper’s Herbal Nicholas Culpeper ( ) published his astrological botany book ‘Herbal’ in His decoction of ‘bruised leaves with pepper in wine’ was most effective at: staunching the bleeding of wounds; suppressing vomiting; clearing acne. Modern uses: salicin, found in the bark, is used to make aspirin for treating malaria.

The salix drug Salicin, named after salix (Latin for ‘Willow’), has no pharmaceutical effect. The body converts salicin to salicylic acid by hydrolysis and then oxidation. >> Do activity WM2 and extract your own salicylic acid!

WM3 Identifying the active chemical in willow bark. What’s the structure of salicylic acid? These chemical tests give some clues: 1. The compound is weakly acidic in aqueous solution. 2. Reactions with alcohols produce fruity- smelling ESTERS. 3. It turns a neutral solution of iron (III) chloride an intense PINK.

What do these tests show? Tests 1 and 2 are characteristic of CARBOXYLIC ACIDS. COOH OH Test 3 shows that PHENOL is present.