week 7 Flashcards
Omeprazole logP. What are its pKa’s
logP= 2.23
pKas 4 and 9
Where is omeprazole absorbed?
small intestine
How may a patient take omeprazole if they are unable to wholly swallow a capsule?
recommend taking drug out of capsule and washing it down with an acidic liquid such as orange juice. Chewing should not be promoted as this will break the coating which helps the drug to work
which aminosalicylates are converted to sodium salts?
balsalazide and olalazine
Action of sulfasalazine
a prodrug with a site of action and breaks down in the colon. It breaks down to the active 5-aminosalisilic acid (5-ASA) (mesalazine). Breakdown to 5-ASA done by gut flora. Inhibits prostaglandin and leukotriene biosynthesis
For a base when will it be fully unionised? When will it be ionised?
Fully un-ionised when the pH is 2 units more than the pKa.
Fully ionised when pH is 2 units less than the pKa.
For an acid when will it be fully unionised? When will it be fully ionised?
Fully un-ionised when pH is 2 units less than pKa.
Fully ionised when pH is 2 units more than the pKa.
Absorption of sulfasalazine
no absorption in stomach as logD is 0.
in ileum molecule does not absorb; too large and so passes to colon
in colon; cleaved to 5-ASA by gut flora. absorbs through aqueous gaps in-between epithelial cells - small molecule.
increasing particle size is known as what?
what is decreasing particle size known as?
increasing- granulation
decreasing - milling
What is the purpose in sieving?
to select powders of desired size
Cutting methods in particle size reduction
Cutter Mill- the material is cut by one or more blades.
Compression methods in particle size reduction
Compression mill, roller mills. A pressure is applied
Impact methods in particle size reduction
Hammer mill. particles are hit by a moving surface or that moving particles hit a surface.
Attrition methods in particle size reduction
Roller mills - principle is pressure and friction
What are cutter mills good for?
elastic, fibrous materials like roots and woods.
What are attrition methods used for?
Ointments, solid in suspensions and pastes.
What are impact methods used on?
Brittle methods
Direct methods of analysing particle size
Sieving
Microscopy; light microscopy(2D images) and electron microscopy (3D images give information on shape but is expensive and a high level of operator expertise is needed)
Indirect methods of analysing particle size
Sedimentation rate; diameter of particle estimated, Andreasen pipette used.
Permeability
In elutriation methods; what is the direction of fluid and what is the direction of sedimentation
fluid direction is opposite to sedimention direction