it effects the drugs stability. hydrolysis by water is common for metabolism of drugs especially when containing (ester,amide)
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describe the process of dissolution.
-drug molecules break away from the solid structure, - a cavity is created for the drug in the solvent structure, - the drug molecule located within the cavity becoming solvated.
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what factors affect solubility?
1) molecular weight 2)H-bonding 3)hydrophobic and hydrophillic groups
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how can u improve a drugs solubility?
1)formation of salt 2) adding water solubilising groups 3) using special dosage forms
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how does salt formation improve solubility?
salts can dissociate in water to form hydrated ions. low melting or oily material can be converted to crystalline solid (solid dosage forms). smaller particles can be produced aids dissolution.
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what is the disadvantage of salt formation?
it has a higher molecular weight, so the proportion of active ingredient is reduced due to solubility so higher doses are required.
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what are the four things to consider when adding a water solubilising group?
1) type of group added 2) reversible or irreversible 3) position of incorporation 4) the chemical route of introduction
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the degree of ionisation is determined by the henderson-hasselbalch equation. what is the equation?
pKa = pH + Log [non-ionised form]/ [ionised form]
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what are the special dosage forms?
micells - drugs with poor water solubility.- mixed micelles= mixture of lipids used in order to optimise delivery .- liposomes= lipophobic drugs via core, lippophillic drugs via bilayer
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what does the partition co-efficient measure?
the way a compound distributes it's self between a lipid phase and an aqueous one
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what is the equation of the partition co-efficient?
Log P =[un-ionised compound]octanol / [unionised compound]water
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Other cards in this set
Card 2
Front
describe the process of dissolution.
Back
-drug molecules break away from the solid structure, - a cavity is created for the drug in the solvent structure, - the drug molecule located within the cavity becoming solvated.
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