You are hereREVIEW ON APPLICATIONS OF POLYMERS IN PHARMACEUTICAL FORMULATIONS

REVIEW ON APPLICATIONS OF POLYMERS IN PHARMACEUTICAL FORMULATIONS


Dental Medicine
Chitin / chitosan have been recognized to accelerate wound healing to attain an aesthetically valid skin surface, and to prevent excess scar formation. In dental medicine, chitin / chitosan is also applied as a dressing for oral mucous wound and a tampon following radical treatment of maxillary sinusitis. Furthermore, it is being investigated as an absorbing membrane for periodoental surgery. Chitin / chitosan has a variety of biological activities and advertised as a healthy food that is effective for improvement and/or care of various disorders, arthritis, cancer, diabetes, hepatitis, etc. In Japan , it is renowned since a three-year old Russian boy whose skin was burnt 90 % in total area

For oral drug delivery: Preliminary study on film dosage form
The potential of chitosan films containing diazepam as an oral drug delivery was investigated inrabbits. The results indicated that a film composed of a 1:0.5 drug-chitosan mixture might be an effective dosage form that is equivalent to the commercial tablet dosage forms. The ability of chitosan to form films may permit its use in the formulation of film dosage forms, as an alternative to pharmaceutical tablets. The pH sensitivity, coupled with the reactivity of the primary amine groups, make chitosan a unique polymer for oral drug delivery applications.

Permeation Enhancer:
It has been reported that chitosan, due to its cationic nature is capable of opening tight junctions in a cell membrane. This property has led to a number of studies to investigate the use of chitosan as a permeation enhancer for hydrophilic drugs that may otherwise have poor oral bioavailability, such as peptides. Because the absorption enhancement is caused by interactions between the cell membrane and positive charges on the polymer, the phenomenon is pH and concentration dependant. Furthermore increasing the charge density on the polymer would lead to higher permeability.

Mucoadhesive Excipient:
Bioadhesivity is often used as an approach to enhance the residence time of a drug in the GI tract, thereby increasing the oral bioavailability. A comparison between chitosan and other commonly used polymeric excipients indicates that the cationic polymer has higher bioadhesivity compared to other natural polymers, such as cellulose, Xantham gum, and starch.

Ophthalmic Drug Delivery:
Chitosan exhibits favorable biological behavior, such as bioadhesion, permeability-enhancing properties, and interesting physico-chemical characteristics, which make it a unique material for the design of ocular drug delivery vehicles. Due to their elastic properties, chitosan hydro gels offer better acceptability, with respect to solid or semisolid formulation, for ophthalmic delivery, such as suspensions or ointments, ophthalmic chitosan gels improve adhesion to the mucin, which coats the conjunctiva and the corneal surface of the eye, and increase precorneal drug residence times, showing down drug elimination by the lachrymal flow. In addition, its penetration enhancement has more targeted effect and allows lower doses of the drugs. In contrast, chitosan based colloidal system were found to work as transmucosal drug carriers, either facilitating the transport of drugs to the inner eye (chitosan-coated colloidal system containing indomethacin) or their accumulation into the corneal/conjunctival epithelia (chitosan nanoparticulate containing cyclosporine). The micro particulate drug- carrier (micro spheres) seems a promising means of topical administration of acyclovir to the eye. The duration of efficacy of the ofloxacin was increased by using high MW (1930 kd) chitosan.

Gene Delivery:
The course of many hereditary diseases could be reversed by gene delivery. In addition, many acquired diseases such as multigenetic disorders and those diseases caused by viral genes could be treated by genetic therapy. Gene delivery systems include viral vectors, cationic liposomes, polycation complexes, and microencapsulated systems. Viral vectors are advantageous for gene delivery because they are highly efficient and have a wide range of cell targets. However, when used in vivo they cause immune responses and oncogenic effects. To overcome the limitations of viral vectors, non-viral delivery systems are considered for gene therapy. Non-viral delivery system has advantages such as ease of preparation, cell/tissue targeting, low immune response, unrestricted plasmid size, and large-scale reproducible production. Chitosan has been used as a carrier of DNA for gene delivery applications. Also, Chitosan could be a useful oral gene carrier because of its adhesive and transport properties in the GI tract. MacLaughlin et al. Showed that plasmid DNA containing cytomegalo virus promoter sequence and a luciferase reporter gene could be delivered in vivo by Chitosan and depolymerized Chitosan oligomers to express a luciferase gene in the intestinal tract.

Preparation of micro spheres:
A novel cellulose acetate/chitosan multimicrospheres (CA/CM) was prepared by the method of w/o/w emulsion. The concentration of cellulose acetate (CA) and the ratio of CA/chitosan (CS) had influence on the CACM size, and appearance. Ranitidine hydrochloride loading and releasing efficiency in vitro were investigated. The optimal condition for preparation of the microspheres was CA concentration at 2% and the ratio of CA/CS at 3:1. The microspheres size was 200–350 μm. The appearance of microspheres was spherical, porous, and non aggregated. The highest loading efficiency was 21%. The ranitidine release from the CACM was 40% during 48 hr in buffers.

Polymethacrylates for pharmaceutical purposes
Neutral poly(meth)acrylates are pharmacologically inactive. Good compatibility with the skin and mucous membranes prompted their use for wound sprays and ointment bases. Crosslinked copolymers based on methacrylic acid serve as ion exchangers for adsorption of active ingredients in the manufacture of sustained-release formulations in the form of tablets and suspensions. For sustained release, active ingredients can also be embedded in water-insoluble polymers, e.g. by compression to tablets together with polymer powders or by extrusion at the softening temperatures of the polymers between 120 and 200 °C. Probably the most important role of poly (meth) acrylates in pharmaceutical manufacture is that of special excipients for coating oral dosage forms and for ensuring controlled release of the active ingredient. Coating of tablets, sugar-coated products, capsules, granules, pellets, crystals and other drug-loaded cores serves to ensure their physical and chemical stability, to enhance patient compliance and to further improve their therapeutic efficacy. Acknowledging the fact that the efficiency of a pharmaceutical dosage form depends not only on the active ingredients it contains but also, and critically so, on the formulation and processing technique, scientists and engineers alike have devoted increasing attention to these parameters in recent years.

Pharmaceutical applications of Chitosan polymer in various dosage forms:
Due to its good biocompatibility and low toxicity properties in both conventional exciepient applications as well as in novel application, chitosan has received considerable attention as a pharmaceutical exceipient in recent decades.

Medical
The polymer Polyvenylpyrolidin was used as a blood plasma expander for trauma victims after the first half of the 20th century. It is used as a binder in many pharmaceutical tablets; it simply passes through the body when taken orally. However, autopsies have found that crosspovidone does contribute to pulmonary vascular injury in substance abusers who have injected pharmaceutical tablets intended for oral consumption. The long-term effects of crosspovidone within the lung are unknown. PVP added to iodine forms a complex called povidone-iodine that possesses disinfectant properties. This complex is used in various products like solutions, ointment, pessaries, liquid soaps and surgical scrubs. It is known for instance under the trade name Betadine. It is used in pleurodesis (fusion of the pleura because of incessant pleural effusions). For this purpose, povidone iodine is equally effective and safe as talc, and may be preferred because of easy availability and low cost.

Technical
PVP is also used in many technical applications:
•    as adhesive in glue stick and hot melts
•    as special additive for batteries, ceramics, fiberglass, inks, inkjet paper and in the chemical-mechanical planarization process
•    as emulsifier and disintegrates for solution polymerization
•    as photoresist for cathode ray tubes (CRT)
•    use in aqueous metal quenching
•    for production of membranes, such as dialysis and water purification filters
•    as a binder and complexation agent in agro applications such as crop protection, seed treatment and coating

TABLE OF PHARMACEUTICAL APPLICATIONS

REFERENCES
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9.    Aiedeh K, Taha MO. Synthesis of chitosan succinate and chitosan phthalate and their evaluation as suggested matrices in orally administered, colon-specific drug delivery systems. Arch Pharm (Weinheim). 1999;332(3):103-107.
10.    Aiedeh K, Taha MO. Synthesis of iron-cross-linked chitosan succinate and iron-cross-linked    hydroxamated chitosan succinate and their in vitro evaluation as potential matrix materials for oral theophylline sustained-release beads. Eur J Pharm Sci. 2001;13(2):159-168.
11.  National Toxicology Program Document. ntp-server.niehs.nih.gov/htdocs Chem_Background/ExSumPdf/Chitosan.pdf.
12.    Hamman JH, Schultz CM, Kotze AF. N-trimethyl chitosan chloride.

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