Novel drug delivery system

1. TITLE : DESCRIBES THE VARIOUS
FACTORS AFFECTING THE DESIGN
MUCOADHESIVE DDS
SUBMITTED BY :
NAME : SUSMITA GHOSH
ROLL NO : 19301920115
YEAR : 4th . SEMESTER : 7th
COURSE : B . PHARM
SUBJECT NAME : NOVEL DRUG DELIVERY
SYSTEM.
SUBJECT CODE : PT 716 B
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2.  Drug action can be improved by new drug delivery system, such
as Mucoadhesive Drug Delivery System (MDDS)
MUCOADHESIVE
MUCO
Inner layer called mucosa.
Inner epithelial cell lining covered with viscoelastic fluid.
Secreted by Goblet cells.
Composed of water and mucin.
ADHESIVE
Tendency substance to remain adhered to surface.
 The adhesive attachment of the drug carrier system to a mucous
layer, the phenomenon is referred to as Mucoadhesion.
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MUCOADHESIVE DRUG DELIVERY SYSTEM

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 Mucoadhesive drug delivery systems are the system which
utilizes the property of bioadhesion of certain polymers
which became adhesive on hydration and can be used for
targeting a drug to a particular region of the body for
prolonged period of time.
 Bioadhesin is defined as an ability of a material to adhere
to a biological tissue for an extended period of time
 Mucoadhesive drug delivery system interact with the
mucus layer covering the mucosal epithelial surface, &
mucin molecules & increase the residence time of the
dosage form at the site of the absorption.
 Mucoadhesive drug delivery system is a part of controlled
delivery system.

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General composition of mucus
* Water – 95%
* Glycoprotein and lipid – 0.5-5%
* Mineral salts – 1%
* Free protein – 0.5-1%

5. NEED OF MUCOADHESIVE DDS
 Prolongs the residence time of the dosage form at the site of absorption.
 Due to an increased residence time it enhances absorption and hence
the therapeutic efficacy of the drug.
 Excellent accessibility.
 Rapid absorption because of enormous blood supply and good blood
flow.
 Increase in the drug bioavailability due to first pass metabolism
avoidance.
 Drug is protected from degradation in the acidic enviroment in the
gastrointestinal tract.
 Improved patient compliance ease of drug administration.
 Faster onset of action is achieved due to mucosal surface.
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6. FACTORS AFFECTING MUCOADHESIVE DDS
A) Polymer related factors :
Molecular weight
Concentration of polymer
Flexibility of polymer chains
Hydrogen bonding
Hydrophilicity
Degree of hydration
Spatial conformation
Cross linking density and swelling
B) Enviroment related factors :
pH of polymer substrate interface
Applied strength
Initial contact time
C) Physiological factors :
Mucin turn over
Disease state 6

7. POLYMER RELATED FACTORS
 MOLECULAR WEIGHT :
The mucoadhesive strength of a polymer increases with
molecular weight of polymeric chain above 100,000.
 CONCENTRATION OF POLYMER :
Concentration of polymer also affects the adhesive strength
and mucoadhesion with mucosal layer.Polymer concentration
in the range of 1-2.5 wt% may show significant mucoadhesive
ability for biomedical purposes.
In liquid mucoadhesives :
In concentrated solution ,the coiled molecules become solvent
deprived t5herefore less availability of chains to interpenetrate.
In solid mucoadhesives :
Higher polymer concentration results in stronger
mucoadhesion.
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8. POLYMER RELATED FACTORS
 FLEXIBILITY OF POLYMER CHAINS :
Flexible nature of polymer is another important
parameter for mucoadhesive property .
Chain length of polymer facilities good penetration and
attachment of the polymer chains with mucosal lining of
the biological membrane.
Helps in improvement of bioadhesive property.
 HYDROGEN BONDING :
Adhesion of polymers is greatly depend upon the
hydrogen bonding.
Higher the hydrogen bonding stronger is the adhesive
strength of the polymers.
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9. POLYMER RELATED FACTORS
 Hydrophilicity :
Hydrophilic functional groups interact with the mucosal
surface via hydrogen bonding.
Polymer swelling results in exposure of potential anchor
site.
Swollen polymer have maximum distance between their
chains leading to increased flexibility and penetration.
 DEGREE OF HYDRATION :
Depending on the degree of hydration adhesive
properties are different . It is maximum at a certain degree
of hydration.
High degree of hydration leading to formation of slippery
, non-adhesive mucilage due to large amount of water
leads to loss of adhesiveness.
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10. POLYMER RELATED FACTORS
 SPATIAL CONFORMATION :
Spatial conformation of polymer determines its adhesive strength.
Non-linear polymers enclose the active groups responsible for
adhesion.
Dextran (molecular weight : 19,500,500) have an adhesive strength
similar to polyethelene glycol (PEG molecular weight : 200,000)
because dextran has Helical conformation (non-linear) where as
PEG has linear structure.
 CROSS LINKING DENSITY AND SWELLING :
Density of cross linking of the polymer is inversely related to its
swelling.
Low density higher swelling larger surface Better
increased hydration mucoadhesion
increased flexibility
Mucoadhesive can be increased by presence of adhesive promoters.
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11. ENVIROMENTAL RELATED FACTORS
 pH OF POLYMER SUBSTRATE INTERFACE :
The pH at the interface of bioadhesive and the biological surface affects
bioadhesion.
Bioadhesives are mainly polyanions with carboxylic acid functional groups.
When pH of the microenviroment is above the pKa of the polymer,it will be
largely ionized.
When pH is below the pKa of the polymer,it will be largely unionized.
The maximum adhesive strength poly(acrylic acid) polymers (pKa=4-5) is
observed around pH 4-5 and decreased gradually above a pH of 6.
 APPLIED STRENGTH :
To place a solid bioadhesive system it is necessary to apply a defined
strength . The adhesion strength increases with the applied strength or with
the duration of its application, up to an optimal level.
 INITIAL CONTACT TIME :
The mucoadhesive strength increases as the initial contact time increases. 11

12. PHYSIOLOGICAL FACTORS
 MUCIN TURN OVER :
The natural turnover of the mucin molecules from the
mucus layer is important.
The mucin turnover is expected to limit the residence
time of mucoadhesive dosage form on the mucus layer.
 DISEASE STATES :
The physiological properties of the mucus are known to
change during disease conditions such as the common
cold, gastric ulcers etc . The exact structural changes
taking place in mucus under these conditions are not yet
clearly understood.
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13. RFERENCES :
 Controlled Drug Delivery edited by Suresh P .
Vyas and Roop K . Khar , 2nd edition , Vallabh
Prakashan , Delhi.
 Mucoadhesive Drug Delivery Systems , edited
by Ahuja A , Khar RK , Ali J , Drug Dev Ind Pharm
1997 , 489-515.
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