suspension

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suspension

settling

avoid formation of "cake"

I-clicker

A flocculated system settles very rapidly not allowing enough time for accurate dosing. what would you try first to fix

d) add a wetting agent

wetting agent is used to make a flocculated system

C) use homogenizer to better breakdown the drug particle

RUIN the flocculated suspension??

B) increase viscosity

flocculated solution is a very loose suspension thus increasing viscosity will allow the drug to settle in a slower rate. giving more time for accurate dosing

A)reduce particle size of disperse phase

we already have a flocculated system! change is particle size can affect the flocculated systemm

disadvantage

lack drug stability data

cause clumps floating around

promote loose settling

fast settling but "fluffy" ( loose structure) = Floc

easily redistributed

we cannot prevent settling might as well control it

process to form "floc", a loose structure due to particle settling very fast

weak particle particle forces

artificially form when particle settle to re disperse

made by additive

adjusting pH and electrolytes

most sophisticated

promote int interactions for particle to repple and prevent from clumping forming cake

Suractants

done by wetting

prevents particle from sticking

clays

cons: add volume

interfere with other particle creating barrier thus help support the floc structure once it forms

all suspension particle WILL eventually settle

once particles settle can form a hard cake that does not re-distribute easily and is to be avoided

preparing

process

add remaining vehicles in parts while mixing

dispersed particle are wetted---> paste

Extemporaneous compound

less stable

from solid--> suspension

Wetting to create barrier

too much

dissolution of drug

bad tase

used to reduce interfacial tension

prevent particles from sticking to each other

creating a barrier to avoid "caking"

surfactants

amphiphilic

cover particles and form a bridge between the lipophilic particle and the hydrophilic medium

classification

coarse

always a suspension

settle under gravity

over 1 micron

Colloidal

may look like solution

suspension/solution

typically do not settle under gravity b/c so small that particle remain suspended

< 1micron

nanometer range

3 main type

parenteral

fastes growing

suspension limitation in the blood is the particle size of the drug.

must be low particle size == looks like solution

particle size can be determined by light transmission through the suspension

large particle size = light does not passes through

small particle size = light passes through

liposomal doxorubicin

most common insulin zinc suspension

externally applied

lotion

oral

most common

oral suspensionn better flexibility in dosing than oral tablet

definition

drug

suspensiod

internal phase

the dispered phase

external liquid phase

dispensing medium

cant see through

will not dissolve

WILL eventually settle over time

finely divided particles distributed somewhat uniformly throughout a vehicle in which the drug exhibits minimum solubility

drug molecule surrounded by drug molecule

Particles( clubs) surrounded by water molecule

Why

slower dissolution and absorption than tablets

better dissolution and absorption than tabelts

mask the tase

dose flexibility

when. liquid is required but drug is not dissolve in liquid or unstable in solution

suspension can improve the stability of undissolved drug

common use

antiimicrobial- unstable in solutions

Antiacid - are inorganic particle that are insoluble in water

good suspension

flocculation

loose structure when settle

thus easily redistributed

FLOC

vehicle

thixotropy is a good vehicle

overtime viscosity increases

under high stress become less viscous

not heavily adjusted to achieve good suspension

easy consistent pour

vehicle viscosity

thixotropy is a good vehicle

over time viscosity increases

high stress --> less viscous

easy to disperse

adjusted via addition

thickening agent

suspending agent

adjusted in accordance to particle size and density to minimize sedimentation rate

the stokes equation cannot determine if particle will readily re-disperse

slow sedimentation rate slow to settle

slow sedimentation rate for stability**

Sedimentation rate

particle density

WANT particle density to be a little but lower than medium

Density of particle a >> than medium

Density of particle less than medium (water)

float

WANT the particle size to be as narrow as possible

10 x increase in particle size results in 100x increase in sedimentation rate

too large

easy to re-disperse

fast to settle

too small

will form cake

slow to settle

particle size

differentiating factor in suspension

stable

particle with the samilar density as medium can afford having more particle because the sedimentation rate is slower

uniform=narrow particle size distribution