Principles

Question 1

How are lipophilic drugs absorbed?

Answer 1

Fat soluble drugs that can pass easily across cell membranes. They can move across the gut wall and so are often given orally as they can easily be taken up by the GI tract

Question 2

How are hydrophilic drugs absorbed?

Answer 2

These readily dissolve in solutions, as they are ionised they cannot pass across the cell membrane readily and require an active transport process to do this. These are usually given parentally i.e. By injection

Question 3

How are drugs absorbed by the oral route?

Answer 3

Travels down the mouth, down the oesophagus into stomach and then into small intestines where they are absorbed.
Pass across the GI tract muscosa to reach the bloodstream
Most drugs are absorbed by non-selective absorption which occurs by the movement from an area of high concentration across the muscosa to an area of low concentration where it enters the hepatic portal circulation and into the plasma.
The more lipid soluble a drug, the more completely it is absrobed

Question 4

How are drugs absorbed by the IV route?

Answer 4

Delivered directly to the bloodstream meaning no drug is lost and the total amount administered reaches the plasma.
Known as 100% bioavailability

Question 5

How are drugs absorbed by the I/M route?

Answer 5

Delivered into the muscle tissue and must diffuse across the interstitial spaces of the muscle tissue and into blood vessels that supply the muscle.
It is common to select muscles with a good blood supply for I/M injection as the drug is likely to be absorbed faster where a good blood supply is present. The drug is now in the plasma and will be distrubted around the body. It will leave the plasma, re-entering the interstitial fluid and then entering the intracellular fluid within the target cell/tissue

Question 6

How are drugs absorbed via the S/C route?

Answer 6

it has to move from the interstital spaces of the s/c tissues to diffuse into the plasma of the blood supply to the area. Once the drug is in the plasma it will be distributed around the body. It will leave the plasma, re-entering the interstitial fluid and then entering the intracellular fluid when it reaches the target cell/tissue