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What is the definition of a drug?
A substance that has some type of physiological effect when introduced into the body
What do most drugs act with ?
Some kind of receptor molecule in the body
How do drugs work?
Receptors generally large protein molecule With an active site, which has a specific shape Only allows a limited number of molecules to fit depending on their shape
Drug Development (Explain the stages)?
Identifying the need Identifying the possible structure of a new drug Modification + Testing the drug activity of a range of molecules –> 1.) In Vitro 2.) Then in Vivo Synthesis of the possible drug or extraction of the drug from a natural source
Animal Studies dose equation?
LD50/ED50
Human Studie dose equation?
TD50/ED50
How do we decide which drug to administer?
• Is it solid, liquid or gas • How quickly/effectively it can reach a certain part of the body • How stable is it in bodily environments
Definition of bioavailability?
The fraction of the administered dosage that reaches the target part of the human body
Factors affecting Bioavailability?
Method of administration The polarity of the drug
What affects the polarity of a drug?
• Dependent on the functional group
Tolerance?
Human body constantly adapts to the chemicals it meets Repeated use –> Drug Tolerance • Need larger amounts for the original effects
Why would increasing the dose be a bad thing in regard to Tolerance?
Increasing the dose • ST –> temporarily overcomes tolerance • LT –> Greater tolerance
Definition of Side effects?
adverse effects which the drug was not prescribe for
Addiction?
When the patient becomes compulsive about taking the drug regardless of the consequences • Increased problems of Tol and SE
What is aspirin?
an Ester
Equation of Aspirin Displayed Formula
Salicylic Acid + Ethanoic acid –> Aspirin This does not produce a vast yield of Aspirin so Ethanoic Anhydride might be needed.
What is the catalyst in the reaction that results in the formation of Aspirin?
Conc. sulfuric acid
How to prep Aspirin?
• Add Salicylic Acid into a conical flask • Add excess ethanoic anhydride and mix reagents carefully -Leave the flask until the reaction is completed • Add cold deionized H2O –> convert excess ethanoic anhydride into ethanoic acid. • Filter the mixture by vacuum filtration • Recrystalise the mixture
How to recrystallize the mixture of aspirin initially made?
Re-dissolve aspirin with hot ethanol Filter using vacuum filtration Cool in ice bath Filter mixture again
does Aspirin have an OH group?
yeah
How soluble is Aspirin in water?
Aspirin is not that soluble in water due to the large non-polar phenyl group
How can aspirin’s aqueous solubility be improved?
Neutralisation with a base to give it ionic sodium salt
Mechanism of Penicillin?
Structure: Beta Lactam ring Four membered ring is strained Makes carboxamide group reactive Ring opens up and reacts with the enzyme that is responsible for the formation of vital cross-links in the new bacterial cell walls Cell wall is weakened and permeable Leads to the bacteria taking too much water and dying
How does Aspirin work?
Mild Analgesic functions by intercepting the pain stimulus at the source, often by interfering with the production of substances that cause pain