Pharmacokinetics elimination Flashcards
1
Q
Factors needed for drug absorption
A
- Must be unionised or liophilic durg to pass the phospholipid bilayer
- Degree of inoisation shows how well it gets absorbed at the specific site
2
Q
How does the drug reach the site of action?
A
- Drug binds to the plasma protein reach the site of action
3
Q
What does metabolism do to the drug
A
- Increases its polarity so that it can be excreated out
- make it more water soluable to excreate through urine
4
Q
Cardiovasular system and drug
A
- Oral route circulation in the plasma so it can reach the site of action
- IV the drug directly enters site of action
5
Q
Drug absorbtion in the GI tract
A
- Arteries carries oxygenated blood to the GI tract and liver
- Incomplete circulation only via liver which metabolises before reaching the vena cava via the hepatic portal vein
- Undifferentiated processing by the liver such as toxins bacteria food and drug
- Goes back to the GI if drug is not fully metabolised
6
Q
Drug metabolism first pass
A
- Liver contains drug metabolising enzymes
- Oral drug travels to the gut then the liver to kidenys or site of action
7
Q
Drug metabolising enzymes
A
- Cytochrome P450
- Alcohol dehydrogenase
- Esterase
8
Q
Phase I metabolism
A
- Oxidation, reduction, hydrolysis
- Conversion of drug molecule to polar group facilitaed by cytochrome p450 - heam containing
- Oral metabolism degare drug faster
9
Q
Phase II metabolism
A
- Addition of extra polar groups such as hydroxyl, carboxylic and amino groups
- Facilitates elimination faster from the blood
- Catalysis by UDP take the metabolised drug molecule and convertto water soluable
- Conjugate glucuronic acid
10
Q
Drugs that require first pass metabolism
A
- ACE inhibitors
- L-dopa parkinsons drug
- Prodrugs
11
Q
Cytochrome P450
A
- Alkyl group in the drug is getting converted by cytochrome P450 into hydroxyl groups
- Requires oxygen and NADPH
12
Q
Drug excreation kidney
A
- Glomerular filteration passive removal of free drugs
- Tubular secreation by active transport
- Reabsorption depending on lipid solubility via organic anionic and cationic transporters
13
Q
Drug excreation other route
A
- Volatile drugs are excreated via lungs
- Via skin and subateous glands
14
Q
Biliary system
A
- Active transport of large molecues into bile
- Excreation by the gut
- Redistribution of molecules by the liver
- Reabsorption blocked by activating charcoal excreated by kidney not into circulation
15
Q
IV drug absorption
A
- High concentration of the drug available in the plasma
- Volume of distribution in lower
- Higher conc of drug higher absorbtion - elimate at higher rate
- 100% bioavailability exponential excreation 1st order some undergo zero order
