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Polymers in Drug Delivery Technology, Types of Polymers and Applications

Authors:
  • Nirmala College of Pharmacy, Atmakur, India
DOI: 10.21276/sajp.2016.5.7.7
305
Scholars Academic Journal of Pharmacy (SAJP) ISSN 2320-4206 (Online)
Sch. Acad. J. Pharm., 2016; 5(7): 305-308 ISSN 2347-9531 (Print)
©Scholars Academic and Scientific Publisher
(An International Publisher for Academic and Scientific Resources)
www.saspublisher.com
Polymers in Drug Delivery Technology, Types of Polymers and Applications
V Sri Vajra Priya*, Hare Krishna Roy, N jyothi, N Lakshmi Prasanthi
Department of Pharmaceutics, Nirmala college of Pharmacy, Athmakur (V), Guntur, Andhra Pradesh, India
*Corresponding author
V. Sri Vajra Priya
Abstract: Polymers play a major role in the development of drug delivery technology by release of two types of drugs
like hydrophilic and hydrophobic. In a synchronized manner and constant release of formulations over extended periods.
There are numerous advantages of polymers acting as an inert carrier to which a drug can be conjugated, for example the
polymer improves the pharmacokinetic and pharmacodynamic properties of biopharmaceuticals through various ways,
like plasma ½ life, decreases the immunogenicity, build ups the stability of biopharmaceuticals, improves the solubility
of low molecular weight drugs, and has a potential of targeted drug delivery. However they have their own limitations,
such as the naturals polymers are most abundant and biodegradable but are difficult to reproduce and purify. Synthetic
polymers have high immunogenicity, which prevent their long term usage. Non-biodegradable polymers are needed to be
sugary after they release the drug at the targeted site. The general characteristic features that makes the polymer a
potential candidate for drug delivery include, safety, efficacy, hydrophilicity, absence immunogenicity biological
inactivity, sufficient pharmacokinetics, and presence of functional groups for covalent conjugation of drugs, targeting
moieties, or formation of copolymer.
Keywords: polymer, pharmacokinetics, controlled drug delivery, target-base drug deliver, co polymer, novel drug
delivery.
INTRODUCTION
Polymers are substances whose molecules have high
molar masses and compressed of a large number of
repeating units. Polymers can form particles of solid
dosage form and also can change the flow property of
liquid dosage form. Polymers are the backbone of
pharmaceutical drug delivery systems. Polymers have
been used as an important tool to control the drug
release rate from the formulation[2]. They are also
mostly used as stabilizer, taste-making agent, and
proactive agent. Modern advances in drug delivery are
now predicated upon the rational design of polymers
tailored specific cargo and engineered to exert distinct
biological functions.
Polymers are both naturally occurring and synthetic.
Among naturally occurring polymers are proteins,
starches, latex and cellulose. Synthetic polymers are
produced on a large scale and have a many properties
and used.
The polymers for the drug delivery system are
classified on the following characteristics:-
Origin- The polymers can be natural or synthetic,
or a combination of both.
Chemical nature- It can protein based, polyester,
cellulose derivatives, etc.
Backbone Stability- The polymers can be
degradable or non biodegradable.
Solubility- The polymer can hydrophilic or
hydrophobic in nature [5,9].
Polymers act as inert carriers to which a particular
drug can be conjugated. There are numerous advantages
of polymer acting as an inert carrier, for example, the
polymer enhances the pharmacodynamic and
pharmacokinetic properties of biopharmaceuticals
though several sources, such as, increases the plasma ½
life, decreases the immunogenicity, boost stability of
biopharmaceuticals, improves solubility of low
molecular weight drugs, and has potential for targeted
drug delivery[1]. Some drugs have a limited
concentration range by which utmost benefit can be
delivered. The concentrations above or below can cause
toxic effects or show no therapeutic effect. On the other
hand, the very slow progress in the efficacy of the
treatment of severe diseases, has suggested a growing
need for a multidisciplinary approach to deliver the
therapeutic to targets in the tissue. Through these new
innovations in pharmacodynamic, pharmacokinetic, non
specific toxicity, immunogenicity, biorecognition and
Review Article
Vajra Priya et al., Sch. Acad. J. Pharm., July 2016; 5(7):305-308
306
efficacy of the drug were generated. These new
strategies were often called as drug delivery systems
(DDS).
BIOMATERIALS FOR DELIVERY SYSTEMS
The polymers in the very starting stage they were
particularly used for non-biological uses, and were
selected because of their desirable physical properties,
for example:
Poly (methyl methacrylate) for physical strength
transparency.
Poly (vinyl alcohol) for hydrophilicity and
strength.
Poly (urethanes) for elasticity.
Poly (ethylene) for toughness and lack of swelling.
Poly (siloxanes) or silicones for insulating ability.
Poly (vinyl pyrrolidone) for suspension
capabilities.
In order for controlled drug delivery formulation, the
polymers must be chemically inert and free from
impurities with appropriate physical structure, minimal
undesired aging, and to readily processable[7,22]. Few
examples
Poly (ethylene-co-vinyl acetate)
Poly (methyl methacrylate)
Poly (vinyl alcohol)
Poly (N-vinyl pyrrolidone)
Poly (acrylic acid)
Poly (2hydroxy ethyl methacrylate)
Polyacrylamide
Poly (methacrylic glycol)
Poly (ethelene glycol)
However in recent years the use of polymers were to
words medical applications and drug targeting few
examples are
Polyrthoesters
Poly (lactide-co-glycolides) (PLGA)
Polyactide (PLA)
Polyanhydride
Polyglycolides (PGA)
ROLE OF POLYMERS IN DRUG DELIVERY:-
Immediate drug release dosage form tablets:
Polymers including polyvinyl pyrrolidone and
hydroxypropylmethylecellulose (HPMC) are found to
be a good binder which increases the formation of
granules that improves the flow and compaction
properties of tablet formulations prior to tableting.
Capsules:
Many of the polymeric excipients used to “bulk out”
capsules fills are the same as those used in intermediate
release tablets. For hard and soft shell gelatin has most
often used[10]. By recent advances HPMC has been
accepted as alternative material for hard and soft
capsules.
Modified drug release dosage forms:
To achieve gastro retention mucoadhesive and low
density, polymers have been evaluated, with little
success so far their ability to extend gastric residence
time by bonding to the mucus lining of the stomach and
floating on top of the gastric contents
respectively[11,12].
Extended release dosage forms:
Extended and sustained release dosage forms prolong
the time that’ systemic drug levels are within the
therapeutic range and thus reduce the number of doses
the patient must take to maintain a therapeutic effect
there by increasing compliance[4,7]. The most
commonly used water insoluble polymers for extended
release applications are the ammonium ethacrylate
copolymers cellulose derivatives ethyl cellulose and
cellulose acetate, and polyvinyl derivative, polyvinyl
acetate[15,17,20].
Gastro retentive Dosage forms:
Gastro retentive dosage forms offer an alternative
strategy for achieving extended release profile, in which
the formulation will remain in the stomach for
prolonged periods, releasing the drug insitu, which will
then dissolve in the liquid contents and slowly pass into
the small intestine.
TYPES OF POLYMERS IN PHARMACEUTICAL
DRUG DELIVERY
Polymers used as colon targeted drug delivery:
Polymers plays a very important role in the colon
targeted drug delivery system. It protects the drug from
degradation or release in the stomach and small
intestine. It also ensures abrupt or controlled release of
the drug in the proximal colon[8].
Polymers in the mucoadhesive drug delivery system:
The new generation mucoadhesive polymers for
buccal drug delivery with advantages such as increase
in the residence time of the polymer, penetration
enhancement, site specific adhesion and enzymatic
inhibiton, site specific mucoadhesive polymers will
undoubtedly be uitilized for the buccal delivery of a
wide variety of therapeutic compounds. The class of
polymers has enormous for the delivery of therapeutic
macromolecules[14].
Polymers for sustained release:
Polymers used in the sustain by preparing
biodegradable microspheres containing a new potent
osteogenic compound[16].
Polymers as floating drug delivery system:
Polymers are generally employed in floating drug
delivery systems so as to target the delivery of drug to a
specific region in the gastrointestinal tract i.e. stomach.
Natural polymers which have been explored for their
promising potential in stomach specific drug delivery
include chitosan, pectin, xanthan gum, guar gum, gellan
Vajra Priya et al., Sch. Acad. J. Pharm., July 2016; 5(7):305-308
307
gum, karkaya gum, psyllium, starch, husk, starch,
alginates etc[13].
Polymers in tissue engineering:
A wide range of natural origin polymers with special
focus on proteins and polysaccharides might be
potentially useful as carriers systems for active
biomoleculesor as cell carriers with application in the
tissue engineering field targeting several biological
tissues[18].
RECENT DEVELOPMENTS IN USE OF
POLYMERS FOR DRUG DELIVERY SYSTEMS
Oraldrugdelivery system has been in practice since
many years as the most widely used root of
administration among all the roots that have been
employed for the systemic delivery of drug via various
pharmaceutical products for different dosage forms. A
large of both synthetic and natural has been studied for
possible application in drug delivery system[6].
The most advantageous property of polymers is that
they have been most widely used now a days. Two
promising synthetic polymers which have been
developed for biomedical applications are form
polyvinylpryolidone and polyethylene glycol acrylate
based hydrogels. Both of them are biodegradable and
forms copolymers with natural macromolecules.
On the other side, natural polymers have the
advantage of high biocompatibility and less
immunogenicity. A special attention has been shown
through the gelatin and collagen which are natural
polymers[20]. Other natural polymers include chitosan,
alginate, starch pectin, casein and cellulose derivatives.
The composites of some of the above natural polymers
with synthetic polymers give added advantages as
carriers for drugs delivery by complimenting the
properties of each other.
Hybrid copolymers of collagen with biodegradable
synthetic polymers polyethylene glycol 6000 and
polyvinylpyrolidone were developed for the controlled
released of contraceptive some drugs have an optimum
range within which maximum benefit is derived, and
concentrations above or below this range can be toxic
or produce no therapeutic belief it at all. On the other
hand, the very slow progress in the efficacy of the
treatment of severe disease, has suggested a growing
need for a multidisciplinary approach to the delivery of
therapeutics to targets in the tissues[19]. From this, new
idea on controlling the pharmacokinetic,
pharmacodynamics, non-specific toxicity,
immunogenicity, biorecognition, and efficacy of drugs
were generated. These new strategies, often called drug
delivery system (DDS), are based on interdisciplinary
approaches that combine pharmaceutics, polymer
science, analytical chemistry, and molecular
biology[25,26].
Polymers are used in the conventional dosage forms
like binders for enteric coted tablets which mask the
unpleasant taste, viscosity enhancers for controlling
flow in liquids[12], gel preparation in case of
semisolids and also used in preparation of transdermal
patches[21,27].
Future trust
Many researchers are working in this filed and have
developed many modify copolymers with desirable
functional groups, who visualize their use not only for
controlled drug delivery systems, but also used for
artificial organs lining, immunology testing, agents in
drug targeting, chemical reactors and substrates for cell
growth[17]. The most potential opportunities for these
polymers in controlled drug delivery lie in the field of
responsive delivery systems, it is expected that, in
future even more than today, researches and doctors
will have a wealth of products using biodegradable
polymers that will help faster patient recovery and
eliminate follow up surgeries[3]. Looking to present
scenario and a wide range of research, total use of these
biodegradable polymers in drug delivery applications is
within reach in the near future.
CONCLUSION
The use if novel polymers not only offers benefits but
also can to be harmful because of the toxicity and other
incompatibilities associate with them. Polymers
possessing a unique strength in their application
towards drug delivery application which enables the
new advancement in the formulating new drug delivery
systems which improves the therapy and treatment .
Care should be taken to properly select polymers while
designing a delivery system. The ultimate goal is to
introduce cost effective ,biocompatible, multifunctional.
less toxic polymers so that the delivery systems pass
through the various phases of clinical trials and benefit
the society . Among various types of polymer hydrogels
polymer blends of natural and or synthetic polymer are
used in the pharmaceutical formulations .In that
controlled drug delivery systems having a advantages
over conventional therapy fall into various categories
such as diffusion controlled chemically controlled,
solvent activated and modulated release systems. On the
whole, polymers are being extensively used in
pharmaceutical industry due to their vast applications.
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The design, synthesis, and properties of novel stimuli-sensitive and genetically engineered biomaterials and drug delivery systems are reviewed. Two approaches to their engineering are presented. One approach is to improve the traditional methods of synthesis, as demonstrated by the example of controlled copolymerization of α-amino acid N-carboxyanhydrides. The other approach, discussed in more detail, uses genetic engineering methods. The design of hybrid hydrogel systems whose components derive from at least two distinct classes of molecules, e.g., synthetic macromolecules and protein domains, is assessed. The design of self-assembling block copolymers is discussed in detail. Finally, the pharmaceutics related applications of these materials are presented.
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