L8 - Absorbtion 1 - The Solvent Flashcards
1
Q
immiscible
A
not forming a homogenous mixture when mixed
2
Q
how do drugs partion between immiscible solvent
A
- due to difference in the solubility in difference phases, drugs will partition between solvents
- e.g.
- drugs going between aqueous and lipid phase (cell walls)
- antibiotics partioning into micro-organisms
- drugs partioning into plastics
3
Q
log P
what does it mean
what does it measure
A
- partition coefficient
- measure of lipophilicity/hydrophilicity
- for unionised molecules
- used as drugs need to cross lipid membranes
4
Q
WHat is the equation for log p and the partition coefficient
A
- P = [Co] / [Cw]
- log P = log [Co]/[Cw]
o = oil
w = water
5
Q
How is it simplified
A
- addiding functional groups from known tables
6
Q
WHat do log P values mean in practice
A
- most in the 1-5 range
- need to soluble enough in lipid phase to cross membranes
- need to be hydrophillic enough to be carried in solution
7
Q
WHat is crystal structure and form
A
- crystals contain highly ordered arras of molecule and atoms held together by non-covalent interactions
- the crystals of a given substance may vary in size, number of and kind of faces
8
Q
WHat types of solid are there?
A
9
Q
what is polymorphism and how does it occur
A
- compounds can crystallise out of solution in a variety of different habits depending on the conditions of crystallisation
- these crystal habits usally have the same internal structure
- however compounds can also crystallise with different internal structure
- polymorphism: molecules arrange themselves in different ways in the crystal
- these different polymorphs are normally reffered to a forms
10
Q
crystal habits
A
external structure of crystal
11
Q
what is the unit cell in a crystal
A
smallest repeating unit
12
Q
what are the properties of polymorphic crystal
A
