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BRS YR2 > Principles of Pharmacology > Flashcards

Principles of Pharmacology Flashcards

(52 cards)

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1
Q

Pharmacology Definition

A

The study of drug action

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2
Q

Therapeutics Definition

A

Drug prescribing and the treatment of disease (more focused on the patient)

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3
Q

Pharmacodynamics

A

what the drug does to the body

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4
Q

Pharmacokinetics

A

what the body does to the drug

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5
Q

Main 3 questions for pharmacodynamics

A
  • Where is this effect produced?
  • What is the target for the drug?
  • What is the produced response after interaction with the target?
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6
Q

What are the 4 main drug targets?

A
  • Receptors
  • Enzymes
  • Ion channels
  • Transport proteins
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7
Q

Selectivity

A
  • lock and key model

- necessary for a drug to be an effective therapuetic agent

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8
Q

What is a factor that impacts dosage?

A

The selectivity of the drug, however it is difficult to accurately predict how much of a drug might bind to the desired target protein

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9
Q

What are the 4 ways drugs can interact with target receptors?

A
  • Electrostatic
  • Hydrophobic
  • Covalent
  • Stereospecific
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10
Q

What is an electrostatic interaction?

A

MOST COMMON

involves hydrogen bonds and Van der Waals forces

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11
Q

What is a hydrophobic interaction?

A

Involved with lipid-soluble drugs

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12
Q

What is a covalent interaction?

A

LEAST COMMON

tendency to be irreversible

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13
Q

What is a stereospecific interactions?

A

due to the presence of stereoisomers and interact stereospecifically with receptors.

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14
Q

Describe the relationship between drug+receptor and the drug-receptor complex

A

Proportional, at equilibrium

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15
Q

Agonists

A

drugs that bind and activate receptors

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16
Q

Antagonists

A

drugs that only bind tot he receptors

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17
Q

Affinity

A

determines the strength of the binding of the drug to the receptor, and therefore the drug-receptor complex

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18
Q

A high affinity leads to…

A

High receptor occupancy

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19
Q

Efficacy

A

the ability of an individual drug molecule to produce an effect once bound to a receptor

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20
Q

Difference between antagonists, partial agonists and full agonists

A

The size of the response caused by the binding of the drug molecule to the receptor

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21
Q

Potency

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A

concentration or dose required to produce a defined effect.

22
Q

Measure of potency

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A

the concentration/dose required to produce a 50% tissue response EC/D50
(half maximal effective concentration/dose)

23
Q

A highly potent drug…

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A

produces a large response at relatively low concentrations

24
Q

A highly efficacious drug…

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A

produces a maximal response, irrelevant of the drug concentration

25
What are the 4 major pharmacokinetic factors?
- Absorption - Distribution - Metabolism - Excretion
26
Absorption
the passage of a drug from the site of administration into the plasma
27
Bioavailability
the fraction of the initial dose that gains access to systematic circulation
28
Difference between absorption and bioavailability
absorption is the process, whereas bioavailability is the outcome of the transfer
29
What are the main forms of drug administration?
``` - IV administration (100%) Lower than 100%: - Oral - Inhalational - Dermal (percutaneous) - Intra-nasal ```
30
What are the 2 main forms of drug transfer?
- Bulk Flow transfer (bloodstream - 100%) - Diffusional transfer (molecule by molecule - <100%, lipid membrane)
31
2 unlikely routes for diffusion
- pinocytosis | - diffusion across aqueous route
32
2 most likely routes for drug transport
- diffusion across lipid membranes (only possible if lipid soluble) - carrier mediated transport (including a transmembrane protein)
33
The solubility of most drugs is...
water soluble not lipid soluble
34
What is the impact of ionisation on solubility?
The unionised form of the drug retains more lipid solubility, and therefore more likely to diffuse across lipid membranes.
35
What does ionisation depend on?
- The dissociation constant (pKa) of the drug | - The pH of the part of the body
36
if the pKa (of the drug) and the pH (of the tissue) are equal...
The drug will be equally dissociated between the 2 forms
37
What pKa do most weak acids have?
Between pKa 3-5
38
For weak acids, as pH decreases...
The unionised form starts to dominate
39
For weak acids, as the pH increases...
The ionised form starts to dominate
40
Factors that effect tissue distribution
- Regional blood flow - Plasma protein binding - Capillary permeability - Tissue localisation
41
Regional blood flow by organs
- Liver: 27% - Heart: 4% - Brain: 14% - Kidneys: 22% - Muscles: 20% changes depending on circumstance (exercise or food)
42
Factors affecting plasma protein binding
- the free drug concentration - the affinity for the protein binding sites - the plasma protein concentration
43
What is the plasma concentration required for a clinical effect in the majority of drugs?
A maximum of 1.2mmol/l | the same as the binding capacity fo albumin alone
44
Saturation and plasma protein binding
Plasma proteins are NEVER fully saturated
45
What causes the difference in the extent of plasma protein binding?
Due to the particular affinity for the protein binding sites for that particular drug
46
What nature of drugs bind better to plasma proteins?
Acidic drugs bind well to albumin.
47
Why do drugs dissociate from plasma proteins?
Only free drug is able to diffuse out of blood and into tissues.
48
What are the different types of capillary structure?
- H2O filled gap junction, continuous - Tight junction (blood brain barrier) - Continuous, discontinuous and fenestrated
49
Transport through continuous membranes.
- Very lipid soluble: diffuse across endothelial cells | - Carrier proteins
50
What are the benefits of the discontinuous capillaries in the liver?
Allows for drugs to easily diffuse out of the bloodstream and match the high metabolic demands of the liver
51
The glomerulus of the kidney and fenestrated capillaries
Main function of the kidney is excretion
52
What is the impact Tissue localisation on drug transport in the BBB?
Drugs move down the concentration gradient, the brain has a high concentration of lipids, the blood has a higher water content. Equilibrium means water soluble drugs are retains in the plasma and vice versa.

BRS YR2 (70 decks)

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