L2: What is a medicine?

Question 1

what is drug absorption?

Answer 1

the uptake of non-metabolised drug, after release from its formulation, from the site of delivery to the systemic circulation

Question 2

what are the routes of delivery?

Answer 2

• oral
• injections (intravenous/muscular/dermal, subcutaneous)
• implants
• topical and transdermal
• pulmonary (inhalation)
• nasal
• buccal and sublingual
• ocular, otic
• rectal, vaginal

Question 3

what is the aim of medicines design?

Answer 3

to get the right drug to the right place at the right dose and at the right rate

Question 4

what does this depend on (aim of med designs)?

Answer 4

• type of drug and situation/case
• physical/chemical properties of the drug and dosage

Question 5

what else do you control if you control the rate and extent of absorption?

Answer 5

the onset, duration and intensity of biological effect, and the +ve effect on the patient

Question 6

What is a drug?

Answer 6

• drug is the active pharmaceutical ingredient (API), the chemical moiety in a medicine which is responsible for the therapeutic effect

Question 7

What is a medicine?

Answer 7

API plus excipients
- dependent on the dosage form and desired drug release

Question 8

what is dosage form?

Answer 8

the physical form in which medication is produced and administered

Question 9

types of dosage forms

Answer 9

• tablets
• capsules
• liquids
• topicals
• inhalers

Question 10

what are major considerations in design of dosage form?

Answer 10

• the physiochemical properties of the drug
• biopharmaceutical considerations
• therapeutic considerations of the disease state and patient to be treated

Question 11

what are biopharmaceutical considerations?

Answer 11

• how the administration route of a dosage form affects rate and extent of drug absorption into the body

Question 12

what do therapeutic considerations determine?

Answer 12

• most suitable type of dosage form
• possible routes of administration
• the most suitable duration of action
• dose frequency

Question 13

what are enteric coated formulations?

Answer 13

layer of protection on the medicine that prevents it from being dissolved in the stomach

Question 14

what is drug delivery system (DDS)?

Answer 14

method of delivery of the drug (pharmaceutical compound) to achieve a therapeutic effect

Question 15

what are examples of DDSs?

Answer 15

• controlled-release systems
• transdermal patches
• injectable systems
• nanoparticles and liposomes

Question 16

what are the steps in drug discovery and pre-clinical development?

Answer 16

• target identification and validation
• drug screening -> hit/lead compound
• lead optimization
• formulation development
• pharmacokinetics and toxicity
• clinical development

Question 17

drug absorption in the GI tract

Answer 17

oral delivery:
- swallowed
- into stomach (dissolved w/o coating)
- into small int. (dissolved w/ coating)
- into ascending, transverse and descending colon
- excreted if not dissolved and absorbed

Question 18

what veins do the intestines go into?

Answer 18

Inferior mesenteric vein
- transverse colon
- descending colon
superior mesenteric vein
- small int.
- ascending colon

into the portal vein into the liver

Question 19

what is the liver?

Answer 19

the major site of detoxification, where drugs are usually metabolised

Question 20

Steps of drug absorption in the GI tract

Answer 20

• solid breaks apart
• particles dissolve forming solution
• absorption across epithelium

Question 21

What are some problems with the drug absroption in the GI track?

Answer 21

• digestive/bacterial enzymes can damage them
• efflux: metabolic enzymes can pump out the molecules as a for of protection from potentially harmful molecules

Question 22

What are factors that affect absorption of small drugs?

Answer 22

• pH: ionises, solubility
• hydrogen bonding (must be broken)
• size: greater size = greater time of absorption
• lypophilicity: has to be balanced so can go in and out of cells

Question 23

What is pharmaceutics?

Answer 23

The science of mkaing medicines

Question 24

What is biopharmaceutics?

Answer 24

The study of the interaction of the medicine with the biological system, allowing the optimisation of DDS

Question 25

What does biopharmaceutics includes?

Answer 25

• chemistry: organic and physical
• chemical analysis
• physical tests
• pre-formulation and formulation science
• disintegration, liberation and dissolution tests
• bioavailability studies
• bioequivalence studies

Question 26

What is bioavailability?

Answer 26

Measure of the quantity of drug which reaches its site of action and the rate at which it gets there

Question 27

What is the equation for bioavailability?

Answer 27

F = Fa x Fg x Fh
F: net oral bioavailability
Fa: fraction absorbed
Fg: fraction escapoing GI
Fh: fraction escaping hepactic metabolism

Question 28

What is pharmacokinetics?

Answer 28

What the body does to the drug

Question 29

What is pharmacodynamics (PD)?

Answer 29

What the drug does to the body

Question 30

What are the determinants of pharamacokinetics?

Answer 30

ADME

• liberation
• absorption
• distribution
• metabolism
• excretion

Question 31

Plasma conc vs time (oral administration)

Answer 31

Duration of action: when the conc of drug in plasma is above minimum effective conc (MEC)
- therapeutic range