Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharmacology And Theraputics 1b > Pharmacokinetics > Flashcards

Pharmacokinetics Flashcards

1
Q

What is pharmacokinetics?

A

how the body affects a specific substance after administration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is drug absorption?

A

the passage of a drug from the site of administration into the plasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is bioavailability?

A

the fraction of the initial dose that gains access to the systemic circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Name five sites of administration

A

Intra-venous
Oral
Inhalational
Dermal (Percutaneous)
Intra-nasal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which site of administration has 100% bioavailability?

A

Intra-venous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How can drugs travel around the body?

A

Bulk flow transfer (through bloodstream)
Diffusional transfer (molecule by molecule across lipid membranes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is pinocytosis?

A

Cell membrane forms vesicle which envelops drug and releases it on the other side of the membrane. Rarely used for drug transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do most drugs move across cell membranes?

A

Across lipid membranes or through transport proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which drugs can diffuse across lipid membranes?

A

Lipid soluble drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are most drugs ?

A

Weak acids or weak bases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What two forms can weak acids/bases exist as?

A

Ionised or unionised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens to a weak acid in its ionised state?

A

Donates protons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens to a weak base in its ionised state?

A

Accepts protons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which state is more lipid soluble: ionised or unionised?

A

Unionised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What determines the state of the drug?

A

pKa (dissociation constant) and pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When will a weak acid be more unionised?

A

When pH decreases (below its pKa)

17
Q

When will a weak base be more unionised?

A

When pH increases (above it’s pKa)

18
Q

Is drug distribution uniform?

A

No - different tissues will be exposed to different amounts of the drug

19
Q

How does regional blood flow affect distribution?

A

Different tissues receive differing amounts of the cardiac output.

More drug will be distributed to those tissues that receive most blood flow

20
Q

What happens to drugs once they enter systemic circulation?

A

They bind to plasma proteins

21
Q

What determines the amount of drug bound to plasma proteins?

A

The free drug concentration
The affinity for the protein binding sites
The plasma protein concentration

22
Q

Which drugs are more heavily bound to plasma proteins?

A

Weak acids

23
Q

How does the concept of tissue localisation apply to drug distribution?

A

Lipid soluble drugs will localise in lipid environments and water soluble drugs will localise in aqueous environments due to the drug equilibrium

24
Q

What is drug metabolism?

A

The conversion of drugs to metabolites that are as water soluble as possible and easier to excrete

25
Q

What is the major metabolic tissue?

A

The liver

26
Q

What are the main enzymes responsible for metabolism?

A

P450 enzymes

27
Q

What are the two phases of drug metabolism?

A

Phase 1 - add a reactive polar group by reduction, oxidation or hydrolysis

Phase 2 - add a substituent group to make the drug inactive and less lipid soluble

28
Q

What are prodrugs?

A

Drugs which require hepatic metabolism to become active

29
Q

What is an issue with oral drug administration?

A

They will be metabolised by the liver before they enter the systemic blood supply, leading to little active drug being circulated

30
Q

Name four routes of drug excretion

A

Via lungs
Via breastmilk
Via kidney (urine)
Via liver (bile)

31
Q

What are the three phases of excretion via the kidneys?

A

Glomerular filtration
Active tubular secretion
Passive diffusion across the tubular epithelium

32
Q

Which drugs are excreted by glomerular filtration

A

drugs under 20,000

33
Q

What is the most important method of drug excretion through the kidney?

A

Active tubular secretion through the proximal tubule, 80% of blood passes through here

34
Q

What does passive diffusion often lead to?

A

Reabsorption of particularly lipid soluble drugs

35
Q

Which factors influence reabsorption?

A

Drug metabolism - phase 2 metabolites are reabsorbed less

Urine pH - weak acids reabsorbed at low pH, weak bases reabsorbed at high pH

36
Q

How are drugs excreted through liver?

A

In faeces

37
Q

What is enterohepatic recycling?

A

Gut bacteria hydrolyse glucuronide metabolites making them more lipid soluble and increases their reabsorption. Leads to prolonged drug effects

Pharmacology And Theraputics 1b (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions