suspension Flashcards
what is a suspension?
fine droplets of insoluble solid particles(dispersion phase) in a liquid (dispersion medium)
how should the dispersible phase be in a well formulated suspension?
dispersible phase should be small and not settle too rapidly and uniform
how should the settle particles be in a well formulated suspension?
should not form a compact sediment which is difficult to disperse
how should the successive doses of well formulated suspension be?
same amount of suspended solid and hence the same dose of drug
how should the well formulated suspension look like?
agreeable odour, colour, taste and texture
how should the dispersion medium of well fomrulated suspension be
should not support microbial growth on storage.
what are the advantages of a well formulated suspension?
used when patient is unable to swallow solid dosage forms
bitter taste of drug is unnoticeable in solid state than the solution state
high surface area of fine suspensions is desirable for fast drug dissolution in GI tract and for fast action of toxin adsorbing compounds or antacids (kaolin or antacid like magnesium hydroxide)
some drugs can hydrolyse and so are not formulated as a solution so a solid form can be formulated as an oral suspension which is also more stable than a solution
what are the disadvantages of oral suspension?
deflocculated and flocculated sediment
what is a flocculated sediment
slow sedimentation to form a firm mass that is impossible to re-suspend (caking or claying)
fast sedimentation to form a loose cake that an re-suspend relatively easy.
even insoluble drug suspension can result in hydrolytic degradation over time
why is deflocculation and flocculation a disadvantage for suspension?
both lead to inaccurate dosing and inelegance.
what is f value and how to calculate?
f= volume of sediment /total volume of suspension
which type of flocculation suspension has a bigger f value (bigger volume of sediment)
flocculated suspension
what is b value and how to calculate?
sedimentation volume of flocculation/ sedimentation volume of deflocculation
what are diffusible solids
insoluble solids that can be suspended in continuous phase for a sufficient length of time so that a dose can be measured
example of diffusible solids
magenisum carbonate
