What are drugs?

Question 1

Define Pharmacology

Answer 1

The science of drugs: their design and synthesis, measurement of the effects of drugs and their mechanisms, absorption, metabolism and excretion.

Question 2

Define Pharmacy

Answer 2

Preparing, preserving, compounding and dispensing of drugs to patients.

Question 3

Define Toxicology

Answer 3

A branch of pharmacology dealing with the toxic effects of drugs including the actions of poisons and unwanted effects of therapeutic drugs.

Question 4

What are the 3 names for drugs?

Give an example

Answer 4

Proprietary Name - Varies between manufacturers e.g Disprin CV
Common Name - The name of the ‘own-brand’ drug e.g Aspirin
Chemical Name - e.g Acetylsalicylic acid

Question 5

Drugs are usually grouped according to their therapeutic use or sometime by their mechanism of action.
What are the 4 main therapeutic categories?

Answer 5

Analgesic
Anti-inflammatory
Anti-pyretic
Anti-platelet

Question 6

What is the mechanism of action for Aspirin?

Answer 6

It is an analgesic that acts as a cyclooxygenase inhibitor.

Question 7

Give 2 examples of mechanisms of action that can be used to class drugs?

Answer 7

Cyclooxyrgenase inhibitors

Selective Serotonin Re-uptake Inhibitors (SSRIs)

Question 8

Give a general definition of what drugs are and how they work.

Answer 8

Drugs are exogenous molecules that mimic or block the action of endogenous molecules or systems. The target for drugs is often a receptor molecule, which has a specific binding site for the drug.

Question 9

What are the different types of pharmacological receptors?

Answer 9

Physiological receptors - Endogenous proteins that are receptors for endogenous chemical signalling compounds such as hormones or neurotransmitters
Enzymes and ion channels - activity and confirmation can be altered when drug binds
Nucleic acids - drugs bind to regulatory sites to influence gene expression

Question 10

What is the difference between an agonist and an antagonist?

Answer 10

Agonist - bound drug activates the receptor

Antagonist - bound drug that prevents the receptor from becoming activated

Question 11

What forces of interaction are found between a drug and its receptor in reversible interactions?

Answer 11

Ionic attractions

Hydrophobic interactions - Exclusion of water holds the drug more intimately with the receptor

Question 12

What forces of interaction are found between a drug and its receptor in irreversible interactions?

Answer 12

Covalent bonding - drug becomes part of the receptor

Question 13

Is the drug-receptor interaction with Aspirin and cyclooxyrgenase reversible or irreversible?

Answer 13

Irreversible

More cyclooxyrgenase is made which is why the analgesic effects of Aspirin is temporary.

Question 14

What is meant by the term Pharmacokinetics?

Answer 14

What the organism does to the drug in terms of absorption, distribution, metabolism and excretion.

Question 15

What is meant by the term Pharmacodynamics?

Answer 15

The sum of all of the actions of a drug on the organism.

Question 16

What factors affect the absorption of a drug?

Answer 16

How much drug enters the system

How quickly the drug enters the system

How the drug is administered

The properties of the subject or patient (Weight, Adiposity, empty stomach or just fed, healthy or has co-morbidities)

The chemical properties of the drug:Molecular size, lipid solubility, ionisation, chemical and metabolic vulnerability.

Question 17

What factors affect the distribution of a drug?

Answer 17

Solubility in blood
Does it stick to proteins or cells in the blood?
Will the drug concentrate in fats or in aqueous compartments?
Does the patient have an adequate circulation?

Question 18

What factors affect the metabolism and excretion of a drug?

Answer 18

Metabolism - does the patient have a healthy, normal functioning liver?
Excretion - does the patient have healthy, normal functioning kidneys?
Are the metabolites active?
Are the metabolites toxic?

Question 19

Outline the steps involved in creating a new drug.

Answer 19

Idea derived from a physiological observation

Generation of a hypothesis

Measurement of the response using starting chemicals in assay systems - if successful, identify active chemicals.

Undertake rounds of chemical optimisation to improve the drug.

Successful testing in animal models and toxicology testing results in a drug candidate - Enters clinical trials

Phase 0 - Administration of drug in healthy subjects using sub-therapeutic doses to determine pharmacokinetic information.

Phase I - Drug given to 20-80 healthy subjects to determine the optimal dose and identify side-effects

Phase II - Drug given to 100-300 patients to determine the effectiveness of the drug

Phase III - Drug given to 1000-3000 patients to determine how the drug compares with current available medicines - Registration with regulatory agencies MHRA, EMEA, FDA

Phase IV - Long-term safety and effectiveness in different populations is determined