Theme 4: Pharmacology

Question 1

What is pharmacology?

Answer 1

The study of the mode of action of a substance

Question 2

What us pharmacokinetics:

Answer 2

What the body does to the drug

Question 3

What are pharmacodynamics?

Answer 3

What the drug does to the body

Question 4

What is a drug

Answer 4

Any substance which affects normal bodily function at cellular level

Question 5

What is the process of pharmacokinetics

Answer 5

1. Drug absorption > process of time a drug is administer > time passes to tissues > available for use by body
   Can be through> passive transport No cellular activity, drug moves from ↑ to ↓ concentration.
   —Diffusion ceases when drug concentrations = on both sides of membrane
   —Most oral drugs use passive transport as move from ↑ concentration in GI tract
   —to ↓ concentration in blood stream
   Or active transport
   - requires cellular energy

Question 6

What are factors that affect drug absorption

Answer 6

1. Fact acting > absorption rate increased depending on number of cells that get the active drug from SL, IV and INH
2. Not so fast > slower when administered PO, IM and SC, GI mucosa, muscle skin have complex membrane systems
3. Very slow > Slowest absorption rates, drugs can take several hours or days to reach peak concentration levels
   Sustained release good example
4. Hepatic proficiency > Oral drugs → liver before circulation to rest of body
   Hepatic first pass effect

Question 7

Other factors affecting drug absorption

Answer 7

Blood flow > increase blood flow means increased drug absorption

Pain and stress > decreased drug absorption associated with change in blood flow, pain decreases movement in GI

Food particles > increased fat and sold means decreased rate of gastric emptying

Drug formation > Affect drug absorption rates and time needed to reach ↑ concentration levels
Liquid forms ↑ absorbed in stomach at the beginning of the small intestine

Question 8

How does metabolism and excretion include?

Answer 8

Humans and indeed most, if not all living species ingest many chemicals for which there are no physiological uses
To counteract this, the organisms concerned have developed various ways to deal with these chemicals so they can be removed from the body
Drugs are dealt with in the same way as unwanted chemicals
It is reasonable to think the body will simply excrete unwanted chemicals via bile, urine
With many chemicals this may not be as simples as it sounds

Question 9

How is drug metabolism happen?

Answer 9

(Also referred to as bio transformation) where drug is turned into more water soluble and excreted

Drugs metabolised in many ways:
Metabolised into inactive metabolites → excreted
Can be converted to active metabolites (capable of exerting own pharmacological action) → further metabolism or be excreted from body unchanged
Prodrugs (inactive drugs) don’t become active until they’re metabolised
Most drugs metabolised by liver enzymes
Also occurs in plasma, kidneys and membranes of intestines
Phase I metabolism (enzymes modify drug chemically) usually results in loss of pharmacological activity
Phase II metabolism (includes conjugation of a drug to phase I to render product soluble for excretion)

Question 10

What is drug excretion

Answer 10

Refers to the elimination of drugs from the body
Primarily achieved via the kidneys leaves body in urine or bile
Can also be excreted through lungs, exocrine glands (sweat, salivary, or mammary glands), skin and intestinal tract