surfactants

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surfactants

liposome

aqueous core surrounded by one or more bilayer membranes alternating with aqueous compartment

form at an appropriate lipid- to - water ratio and temp

formed by phospholipids

via: signification homogenization ultrasonification

NOT spontaneous

two hydrophobic chains that tends to form lamellar phase

drug delivery for both hydrophobic and hydrophilic

good for antibodies and vaccination

issue

tissue distribution

vesicle clearance rate

low stability in blood and interstitial fluids

classified based on their size and the number of lamellae

MLV multomellar vesicles

LUV Large unilamellar vesicles

SUV small unilamellar vesicles

Classification:

HLB *** memorize the right side

HLB

Antifoaming agent 2-3

w/o emulsifying agents 3-6

wetting and spreading agents 7-9

o/w emulsifying agents 8-16

detergents 13-15

solubilizing agent 15-18

HLBmix= Fa(HLBa)+Fb(HLBb)

low HLB= more lipophilic

higher HLB= more hydrophilic

range 0-20

**emulsifier must be more soluble in continuous phase

surfactant as emulsifying agent 8-18

7-9 surfactant act as wetting agent

3-6 W/O

8-18 O/W

hydrophilic-lipophilic balance

by its hydrophilic group ( polar end )

non ionic

poor as a surfactant

may be water soluble or insoluble depending on functional group

water insoluble

fatty acid

glycerol esters

fatty alcohols

water soluble

polyoxyethylene groups

stability

good compatibitlity

no charge

Zwitterionic

isoelectric point

behave similar to nonionic surfactant

both positive and negative charges upon full ionization

carboxylate

ammonium group

example

alkyl betaine

glycine

Cationic

Benzylalkonium chloride ( BAC/BAK)

function in protonated state

positive charge

quaternary ammonium

retains charge over the entire pH range

amines

ph depended

nitrogen atom

Anionic

above the pKa will ionize

if countering are mono valiant most likely not soluble

if the counter ion are sodium or potassium= water soluble

in a basic solution acid are negatively charge

Sodium Lauryl sulfate (SLS)

most common surfactant

emulsifying agent

wetting agent

most widely used class

negative charge

phosphate

sulfonate

sulfate

caboxylate

clinical applications

lung surfactant

premature infant have not enough lung surfactant= death

decreasing the surface tension

decreases pressure inside alveoli

prevents collapse of alveoli

covers the surface of alveoli contacted with air

nonionic often aid in bacterial growth

antibacterial

cationic and ionic absorb onto bacteria surface --> leaking of lipid cell membrane--> bacterial death

liposomes

antibodies

IM/ Subq: liposome get into the lymphatic system; vaccine delivery

reaction with antibodies to be phagocytize into the liver and spleen allowing for passive targeting of these sites

*surface- active agents? surfactant

surfactant reduces surface tension

surface tension

surface activity

this is to achieve minimum energy state

amphiphilic orientation to remove the hydrophobic group from the aq. environment

lowering the surface tension

at the surface particle are not completely surrounded which results in a net inward force attraction exerted on molecules at the surface by the molecules in the bulk solution

contracted surface = minimum free energy

thus liquid surface contracts and form a sphere spontaneously

lower the interfacial tension between the phases (oil and water) blending enable interaction of two phase

miceller formation

wetting

micelle

shape

nonionic surfactants = lower cmc= larger micelle

mostly affected by hydrophobic region and any steric interactions

increase in hydrophobic chain

bigger size

low CMC

depend upon surfactant's molecular geometry

drug delivery for hydrophobic materials

hydrophilic shells

hydrophobic core

spontaneous

Surface tension decreases until CMC critical micelle concentration

More surfactant= less surface tension

surfactant associating to itself encapsulating and forming a sphere

hydrophobic groups withdrawing form the aqueous phase

concentration that micelles form to attain minimum free energy state

too much surfactant requires energy to keep all in a solution thus to lower energy form micelle = Entropic Effect

definition

emulsion formation

Wetting

contact angle

high = poor wettability > 90

low = good wettability <60

the extent to which a solid will physically interact with a liquid

lowers the interfacial tension between phases enables interaction

surface active agents amphiphilic in nature

hydrophobic head

hydrophilic region