Option D: Medicinal Chemistry

Question 1

What are the five methods of drug administration?

Answer 1

• Orally (through mouth)
• Parenterally (through injection)
• Inhalation
• Rectally
• Transdermally (through application to skin)

Question 2

What are the three parenteral methods of drug admministration?

Answer 2

• Subcutaneous (under skin)
• Intramuscular (into muscle)
• Intravenous (into vein)

Question 3

What is the effective dose (ED50)?

Answer 3

The minimum amount of bioactive compound required to cause a therapeutic effect in half the population

Question 4

What is the toxic dose (TD50)?

Answer 4

The minimum amount of bioactive compound required to cause an unacceptable adverse effect in half the population

Question 5

What is the lethal dose (LD50)?

Answer 5

The minimum amount of bioactive compound required to kill half the animal population

Question 6

How is the therapeutic index (TI) measured?

Answer 6

TI = TD50 / ED50

Question 7

What is the therapeutic window?

Answer 7

The range of values between ED50 and TD50

Question 8

What is bioavailability?

Answer 8

The fraction of administered dosage that enters the bloodstream (or reaches target organ)

Question 9

Why do drugs taken orally have a lower bioavailability than drugs administered intravenously?

Answer 9

• Not all drug absorbed
• Some destroyed by enzymes/stomach acid
• some metabolised due to first-pass effect (first destination is liver where bioactive compound may be metabolised and cleared)

Question 10

What is the importance of polar and non-polar groups in drugs?

Answer 10

• Polar groups are soluble in water
• Non-polar groups can pass through hydrophobic cell membranes and blood-brain barrier

Question 11

What are side effects?

Answer 11

Non-beneficial/unintentional effects a drug has on the body

Question 12

What is tolerence?

Answer 12

When a person needs an ever increasing amount of a drug to gain the desired effect

Question 13

What is addiction?

Answer 13

A compulsion to keep taking a drug

Question 14

How do drugs interact with the body?

Answer 14

Bioactive compound must interact with and fit the biding site of an enzyme or cellular receptor

Question 15

What are the two ways companies identify a lead compound?

Answer 15

• Screening of a large library of compounds
• Seeking to improve an existing compound

Question 16

What are five factors to consider when choosing a compound for clinical trials

Answer 16

• yield of required drug
• cost to synthesize drug
• side effects
• solubility of drug
• chemical stability of compound

Question 17

What is the placebo effect and how can it be prevented?

Answer 17

Patients report an improvement in condition without taking the drug. This can be prevented by using a placebo (medicine without the active ingredient) and a double-blind trials where neither patients nor doctros know if the patient has a placebo

Question 18

Which plant is salicylic acid obtained from?

Answer 18

Willow bark

Question 19

What does an analgesic drug do?

Answer 19

A drug that relieves pain

Question 20

What does an anti-inflammatory drug do?

Answer 20

A drug that reduces swelling

Question 21

What does an antipyretic drug do?

Answer 21

A drug that reduces fever symptoms

Question 22

What does an anticoagulant drug do?

Answer 22

A drug that thins the blood (reducing blood clotting)

Question 23

How does aspirin relieve pain?

Answer 23

It binds irreversibly with COX, preventing it from releasing prostaglandins

Question 24

What is a prostaglandin?

Answer 24

A lipid responsible for transmission of pain receptors in the brain

Question 25

What is a prophylactic?

Answer 25

A medicine that is taken as a preventative measure

Question 26

What is a synergistic effect?

Answer 26

When one drug increases the effectiveness of another

Question 27

How can you improve the solubility of aspirin in water?

Answer 27

Deprotonise the carboxylic acid group with NaOH to create a carboxylic salt (soluble ionic compound)

Question 28

Why do most ionic compounds dissolve well in water?

Answer 28

Salts form ion-dipole attractions with water molecules and become well solvated

Question 29

How was penicillin discovered?

Answer 29

Alexander Fleming left a petri dish with bacteria in open and a blue-green mold formed (penicillium), inhibiting the growth of bacteria

Question 30

Why is a beta-lactam ring very prone to attack by nucleophiles?

Answer 30

It has very small bond angles of 90 degrees, creating lots of ring strain

Question 31

How does penicillin kill bacteria?

Answer 31

* opens the beta-lactam ring * binds irreversibly with transpeptidase enzyme * preventing cross-linking in cell walls and weakening them * causing cells to fill with water due to osmotic pressure and burst and die

Question 32

What defense have resistant-bacteria developed to penicillin?

Answer 32

Synthesis of penicillinase (deactivates penicillin before it can react with transpeptidase enzyme)

Question 33

What are the three main causes of antibiotic resistance?

Answer 33

* Over-prescription (exposes lots of bacteria to penicillin meaning only resistant ones survive and multiply) * Poor patience compliance (stop antibiotics course early as they feel better) * Agriculture (antibiotics used in livestock to keep animals healthy but still present in meat and dairy)

Question 34

What are MDR bacteria and how should they be treated?

Answer 34

Multidrug resistant bacteria that should be treated with a cocktail of drugs

Question 35

What is opium extracted from?

Answer 35

Opium poppies

Question 36

How do mild analgesics relieve pain?

Answer 36

They block transmission of pain impulses at injury site

Question 37

How do strong analgesics relieve pain?

Answer 37

They block opioid receptors in the brain so they can't receive pain impulses

Question 38

What is a prodrug?

Answer 38

An inactive drug which is metabolised into and active drug in the body

Question 39

Which sort of compounds pass easily from the bloodstream into the brain?

Answer 39

Non-polar compounds

Question 40

What are withdrawal symptoms?

Answer 40

Abnormal physical or psychological features following the abrupt discontinuation of a drug addiction

Question 41

What are the roles of pepsin and hydrochloric acid in gastric juice?

Answer 41

* Pepsin: enzyme that breaks proteins into amino acids and peptides * Hydrochloric acid: kills germs, denatures proteins, provides optimum pH for enzymes

Question 42

What are antacids?

Answer 42

Weak Bronsted-Lowry bases that neutralise excess stomach acid

Question 43

What's the purpose of antifoaming agents?

Answer 43

Allows CO2 to coalesce to help it escape easier

Question 44

What's the purpose of alginates?

Answer 44

Forms a layer on top of gastric acid preventing it from rising into the oesophagus and causing heartburn

Question 45

How do ranitidine, omeprazole and esomeprazole regulate acid secretion?

Answer 45

* Ranitidine: blocks H2-histamine receptors, preventing histamine from releasing stomach acid * Omeprazole and esomeprazole: inhibit the proton pump enzyme, preventing the release of H+ ions (lasts longer than ranitidine)