Significant advances have been made in development of various drug delivery devices with the help of polymers.
The earliest DDS first introduced in 1970s were based on polymers formed from lactic acid.
Today polymeric materials still provides most important avenues of research primarily because of ease of processing & ability of researchers to readily control their chemical & physical properties via. Molecular system.
BIOADHESIVE POLYMERS IN MUCOADHESIVE DRUG DELIVERY SYSTEMS BIOADHESIVE PROPERTIES CHARACTERISTICS Poly-hydroxyl Butyrate Poly(e-caprolactone) Polyorthoesters Polyphosphazenes Polycyanoacrylates Polyvinyl Acetate Polyethyleneoxide-b-propylene oxide Biodegradable Properties can be changed by chemical modification Surface eroding polymer Can be tailored with versatile side chain functioning Biodegradable Biocompatible Amphiphillic surfactant Biocompatible Matrix for DDS Cell encapsulation Sustained DDS, opthalmology To make films, Hydrogels in DDS Surgical adhesives, glues in DDS Gels & Blended membranes in DD & Immobilization Protein delivery
SYNTHETIC POLYMERS USED IN SUSTAINED RELEASE DRUG DELIVERY SYSTEMS
Sustained Release DDS follows 1 st order release kinetics.
Increased crosslinking of polymers decreases diffusion rate & thus improves sustained release properties of polymers & decreases mucoadhesivity.
Synthetic Absorbable Polymers- include homopolymers like PLA, PGA, PCL, Polytrimethylene carbonate, Poly(p-dioxanone) & copolymers like- Poly lactide-co-glycolide, Poly (glycolide-co-trimethylene carbonate).
SYNTHETIC POLYMER APPLICABILITY Poly(Monosteroyl Glycerol-co-succinate) For Sustained release of Theophylline/ Risperidone from microparticles in-vitro Polyvinyl Acetate For sustained release capsules of Nifedipine Eudragit RLPM, RSPM & HPMC Sustained release of theophylline
SYNTHETIC POLYMER BASED VECTORS IN GENE THERAPY
SYNTHETIC POLYMERS USED IN OPTHALAMIC DRUG DELIVERY SYSTEMS
Properties of synthetic Polymers considered for Opthalamic DDS-
Non-Toxic, Biodegradable, Biocompatible, Optically transparent, Do not impede vision, Tolerable, good retention properties, mucoadhesivity.
Non-Biodegradable polymeric bioadhesives used as drug delivery systems:-
Copolymers based on Vinylpyrrolidone, Methacrylic acid, Polydimethylene- siloxane, Poly (N-isopropyl acrylamide), PAMAM dendrimers.
CONTD… SYNTHETIC POLYMERS APPLICABILITY Polyhydroxy ethyl - methacrylate Used to formulate liposomes loaded with Dimyristoyl phosphatidylcholine (DMPC). It is optically transparent & release drug for a period of 8 days. Poly (D,L-lactide) Biodegradable polymer used for sustained retinal delivery of Celecoxib to inhibit diabetes induced Retinal oxidative demage Polyanhydrides, Polyorthoesters For sustained release of 5-FU Poly (Ɛ-caprolactone) rod shaped implants Tolerated by retinal tissues & used to release corticosteroid triamcinolone acetide over 4 weeks
SYNTHETC POLYMERS USED IN TRANSDERMAL DRUG DELIVERY SYSTEM
Polymers are the backbone of TDDS.
TDDS are fabricated as multilayered polymeric laminates or drug- polymer matrix is sandwiched between two polymeric layers i.e. backing layer & inner polymeric layer which act as adhesive & Rate- controlling membrane.
TDDS is formulated either as Matrix form / Reservoir form.
IN TDDS POLYMERS ACTS AS MATRIX FORMERS BACKING LAYERS RELEASE LINERS RATE –CONTROLING MEMBRANE PRESSURE- SENSITIVE ADHESIVES (PSAs)
Microscopic sac that encloses a volume with molecularly thin membrane. The membrane are self- directing assemblies of amphiphilic molecues with dual hydrophobic- hydrophobic characters.
SYNTHETIC POLYMER APPLICABILITY Non-ionic Polyethylene-oxide- Poly butadiene To form vesicles in aqueous solution PMOXA- PDMS- PMOXA Water soluble & midblock is hydrophilic (PEO- Polyethylethylene To form polymerosomes in aqueous solution for encapsulating Doxorubicin