drug delivery gels

7/26/2019 Drug Delivery Gels

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DRUG DELIVERY

GELS

BY:-

NIKUNJA BASINI PATI

M.PHARM 2ndSEM

PHARMACEUTICS


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POLYMERS :-These are the stretch/chain of monomers,linked covalently to each other

!"LY#ERS are e$tensively %sed in dr%&delivery for '( rheolo&y control,

control of dr%& release rate, sta)ili*ation of colloidal dr%&carriers, sol%)ili*ation of s+arin&ly sol%)le

dr%&s

!"LY#ER GELS'( fre%ently %sed todescri)e -thick. or -non o0in& systems.The are s eciall reco ni*ed for their


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HYDROGELS:-

these are 1(D, 0ater s0ollen +olymerscom+osed of mainly hydro+hilic homo+olymers/co+olymers

They are rendered insol%)le d%e to+resence of chemical or +hysical cross links

Generally s%ita)le for molec%lar sta)ili*ation of s+arin&ly sol%)ledr%&s, for )ioadhesion, for desired rheolo&ical

+ro+erties


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Generally %sed hydro&els'(

!V2 ( !oly3vinylalcohol4

!5E#2 6 !oly37(hydro$yethyl methacrylate4 !E" ( !oly3ethylene o$ide4 !EG ( !oly3ethylene &lycol4 !8V! 6 !oly38 6 vinyl 6 7( +yrollidone4 !EV2c ( !oly3ethylene( co( vinyl acetate4 !##2 ( !oly3methyl methacrylate4 !22 ( !oly3acryl amide4


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Classifcation based on :-

8at%re of side &ro%+s 3as ne%tral 9 ionic4, 8et0ork mor+holo&y3as amor+ho%s,semicrystalline, hydro&en( )onded str%ct%res,

s%+ermolec%lar str%ct%res, 9 hydro(colloidala&&re&ates

8et0ork str%ct%res 3as macro+oro%s,micro+oro%s, or non+oro%s4


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5ydro&els have fo%r key +ro+erties:- s0ellin& de&ree, )iocom+ati)ility,

+ermea)ility 9 s0ellin& kinetics

5ydro&els are %sed d%e to their'(e$cellent )iocom+ati)ility,

hi&h 0ater content,

r%))ery nat%re,+rotection to the dr%& 9

control release of sol%te


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#ainly %sed as devices to +rovide time(inde+endent,

sustained release , controlled release of)ioactive a&ents

)y mani+%lation of the pol!er

co!position and the de"ice #eo!etr$

There)y, most im+ortant characteristics ineval%atin& the a)ility of +olymeric &els forcontrolled release system are '(

net%or& per!eabilit and s%ellin#

be'a"ior$


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!arameters that de:ne the str%ct%re and+ro+erties of s0ollen hydro&els are '(!olymer vol%me fraction in the s0ollen state 6 ;

E


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Cross lin&ed structure o( a'dro#el

0here, #cis the molec%lar

0t of +olymer chains )et0een cross

#c , =


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E%ili)ri%m s0ellin& theories '(

)eutral 'dro#els :-

S0ellin& of these &els has )een de+icted %sin&

a G%assian distri)%tion of +olymer chains

it is &overned )y the elastic retractive forces ofthe +olymer chains and the thermodynamic

com+ati)ility of +olymer and the solvent

There)y, total free ener&y chan&e %+on s0ellin&is 0ritten as' > G ? > Gelastic @ > Gmi$


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It 0as f%rther develo+ed takin& intoconsideration,

>A 3chemical +otential chan&es in the solvent4,

B 3+olymer( solvent interaction4

# 3molec%lar 0ei&ht of the linear +olymer chains)et0een cross links4 etc


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*onic 'dro#els:-

These contain anionic/ cationic side &ro%+sattached

Cor e&, 2nionic &els (((( the side #roups areunioni+ed belo% t'e pa "alue$

2)ove this val%e they &et ioni*ed ((((&els s0ell d%e to develo+ment of a lar&e osmotics0ellin& force d%e to +resence of ions

In these &els,

5i&her the ionic content ((((((((((more 0ill )es0ellin&


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The vario%s models have )een de+icted fors0ellin& of ionic &els, takin& into consideration

> A 3chan&e in chemical +otential of the solvent4I 3Ionic stren&th of +olymers4

a 9 ) 3dissociation constant4

+5 of the environment

>+5


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R%))er elasticity theory'(

Elastic )ehavior of cross linked +olymers has)een analy*ed %sin& (((((((( classical thermodynamics,statistical thermodynamics, and

+henomenolo&ical models 9 vario%s e%ationshave )een de+icted

like, for a system of n chains, thechan&e in the 5elmholt* free ener&y %+on elasticdeformation can )e 0ritten as'

3


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8et0ork +ore si*e alc%lations ' (

In controllin& the rate release of a dr%&

2 direct techni%e for meas%rin& this is %asielastic laser(li&ht scatterin& / electron microsco+y

Indirect ones are merc%ry +orosimetry, r%))er elasticitymeas%rement, or e%ili)ri%m s0ellin& e$+eriments

Fased on crosslink density, this can )e determined as,

0here , = is the net0ork +ore si*e is the elon&ation of +olymer chains in any direction

ro is the end(end distance of +olymer chains)et0een cross links


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Di


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Microporous 'dro#el'(

have +ore si*e 3HH 6 HHHM4

dr%& trans+ort occ%rs d%e to com)inationof molec%lar di


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)onporous 'dro#els'(

have +ore si*e 3H 6 HH M4

here chains are densely +acked

Dr%& trans+ort only )y di


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!re+aration of hydro&els '( 5ydro&el +ro+erties are adO%sted thro%&han a++ro+riate mi$ of hydro+ho)ic 9 hydro+hilicmonomer, ionic monomers 9 cross linkers

8e%tral 5ydro+hilic

#onomers5ydro$yalkyl acrylates

5ydro$yalkylmethaacrylates

8( s%)stit%ted acrylamides

8( vinyl 6 7(+yrrolidone

8e%tral 5ydro+ho)ic

#onomers 2crylics

#ethacrylics

Vinyl acetate

2crylonitrile

7,P( +entadiene((ol Styrene


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rosslinkin&monomers8, 8. 6

methylene)isacrylamide

Ethylene &lycoldimethacrylates

7, 7.( 3+(+henylenedio$y4diethyldimethacrylate

Divinyl)en*ene

Triallylamine

#ethylene)is3P( +henyl

isocyanate4

Ionic monomers

2nionic (((((((((((( 2crylic acid

#ethacrylic acid

rotonic acid

Sodi%mstyrenes%lfonate

ationic(((((((((((((

Vinyl+yridine

2minoethylmethacrylates

7( methacryloylo$y(trimethylammoni%m chloride

5 d l th i


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5ydro&el synthesis'( chemical crosslinkin& of linear+olymers

radiation crosslinkin& of linear+olymers +hysical crosslinkin& of linear

+olymers co+olymeri*ation/ crosslinkin&synthesis from monomers a4 )%lk/ sol%tion+olymeri*ation )4 s%s+ension+olymeri*ation

l i: i


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lassi:cation'(

5ydro&el 6 )ased dr%& delivery systems areclassi:ed as,

Di


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Dr%& release from a hydro&el )ased matri$ delivery

system

S0ellin& controlled systemshemically controlled systems

erodi)le dr%& delivery systems +endent chain systems

Environmentall res onsive s stems


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Dr%& release from a hydro&el( )ased s0ellin& controlledsystems

Dr%& release from hydro&el()ased erodi)le delivery

2 li ti


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2++lications '(In dr%& delivery systems

3maOor &oal is delivery of dr%&s atconstant rate4Varieties of hydro&els ,

0ide di


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oncl%sion'(

5ydro&els have )ecome aim+ortant 9

vital re%irement in advanced dr%& deliverysystems


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5ydro&els' S0ellin&

Q U+on +re+aration the hydro+hilic &el is )ro%&ht in contact

0ith 0ater to yield the :nal solvated net0ork str%ct%re

Q Thermodynamics com+ati)ility favor the interaction of

macromolec%lar chains solvent molec%les

Q Th%s the net0ork e$+andsQ The thermodynamically driven s0ellin& force is

co%nter)alanced )y the retractive force of the crosslinked

str%ct%re

Q T0o forces )ecome e%al at some +oint and e%ili)ri%mis reached


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5ydro&els' S0ellin&

Q De&ree of s0ellin& can )e %anti:ed )y'

6 ratio of sam+le vol%me in the s0ollen state to vol%me

in the dry state

6 0ei&ht de&ree of s0ellin&' ratio of the 0ei&ht of

s0ollen sam+le to that of the dry sam+le

Q Nhy is the de&ree of s0ellin& im+ortant

6 sol%te di


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5ydro&els' S0ellin&

Q 5i&hly s0ollen hydro&els'

6 cell%lose derivatives

6 +oly3vinyl alcohol4

6 +oly38(vinyl 7(+yrrolidone4, !8V!

6 +oly3ethylene &lycol4

Q #oderately or +oorly s0ollen hydro&els'

6 +oly3hydro$yethyl methacrylate4, !5E#2 and

derivatives

Q "ne may co+olymeri*e a hi&ly hydro+hilic

monomer 0ith other less hydro+hilic monomers

to achieve desired s0ellin& +ro+erties


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5ydro&els' 2++lications

Q Fiomedical %se d%e to )io( and )lood(com+ati)ility

Q !harmace%tical %se d%e to hydro+hilicity

3controlled/s%stained dr%& release4

Q Earliest )iomedical a++lication contact lenses

6 &ood mechanical sta)ility6 favora)le refractive inde$

6 hi&h o$y&en +ermea)ility

6 needs hy&ienic maintenance

6 %na)le to correct for asti&matismQ l%)ricatin& s%rface coatin&

6 %sed 0ith catheters, draina&e t%)es and &loves

6 non(to$ic


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Q arti:cial tendon and cartila&e

Q 0o%nd healin& dressin&s 3Vi&ilon, 5ydron,

Gel+erm4

6 non(anti&enic, e$i)le 0o%nd cover

6 +ermea)le to 0ater and meta)olites

6 lo0(stren&th

Q arti:cial kidney mem)ranes

Q arti:cial skin

Q ma$illofacial and se$%al or&an reconstr%ction

materials

Q vocal cord re+lacement


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Q !harmace%tical a++lications

6 monomer com+osition and relative amo%nts of m%lti(+olymer

hydro&els can )e varied to alter the di


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References '(

E8YL"!EDI2 of D!S Vol(7 , Fy , Edit' Mat'io%it+

$ +&no 1W( PX

000 Niki+ediacom

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