Red pill? Blue pill? How about a polymer pill that does it all?
All other reagents used were of analytical grade. Eudragit ® RS 12.5, Eudragit ® RS 100, Eudragit ® RS PO and Eudragit ® RS 30 D shows low permeability and sustained release profiles. Eudragit ® RS 12.5 is available as organic solution with 12.5 % solution in acetone and alcohols and shows miscibility in dichloromethane, ethyl acetate and water. Eudragit ® RS100 is a solid substance in form of colorless, clear to cloudy granules with a faint amine-like odor and forms 97 % solution in acetone and alcohols and also soluble in solvents like dichloromethane and ethyl acetate.
This indicated that the enteric polymer, Eudragit F, prevented the cationic chitosan from dissolving in the stomach, thus facilitating colon drug delivery. Mesalamine colon DDS product, containing an enteric coating layer of Eudragit S, is widely used in patients.
The use of a bioadhesive polymers is recommended for (a) drug controlled release; (b) active substances directed to absorption in specific sites; (c) increasing the medicine residence time into the body and (d) prodrugs . The object of the invention is to provide a site directed drug delivery system providing a controlled release of L-dopa, carbidopa and/or their combinations and L-α- methyldopa which eliminates or at least reduces the deleterious side effects of these drugs. propanoic acid) combined with levodopa (L-dopa) is already used in controlled release formulations with the trade name Sinemet™ to minimize the adverse reactions caused by levodopa . L-α-methyldopa, the L form of α-methyl-β- (3, 4- dihydroxyphenyl) alanine, is an analogue of levodopa and an important drug in the therapeutic treatment of hypertension. The anti-hipertensive activity of the DL racemic form of α- methyldopa was described in US 2 868 818, but it was found latter that the L form, substantially free of the D or rectus spatial configuration, should be more potent and less toxic than the racemic mixture (see US 3 344 023) .
The drug and the chitosan are mixed into a homogeneous mechanical powder mixture which is granulated and then optionally tabletised. The granulation may be performed with an enteric polymer (such as a copolymer of methacrylic acid) or the granules may be provided with a porous enteric coating.
10. A delayed release drug formulation as claimed in Claim 1 , wherein said third polymeric material is said non-ionic polymer. 9.
Kataoka and coworkers have developed a pH-sensitive polymeric micelle DDS for doxorubicin based on block copolymers of PEG-block-poly(aspartate) (PEG-b-P(Asp)). Doxorubicin molecules were conjugated to the polymer backbone through hydrazone linkage formation .
14. A delayed release drug formulation as claimed in any of the preceding claims, wherein the buffer is a phosphate salt. 12. A delayed release drug formulation as claimed in any of the preceding claims, wherein the inner layer comprises at least one buffer agent and at least one base.
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One of the most important attributes of PEG is that it conjugates proteins, peptides, and non-peptide drugs which are less antigenic and less immunogenic and remain stable towards degradative enzymes. PEG can be copolymerized with aliphatic esters like poly(lactic acid) to enhance the biocompatibility of the polymers followed by use in drug delivery and tissue engineering applications. Atta et al. prepared pH sensitive chitosan and poly(ethylene glycol) (different molecular weights) blended hydrogels (CS/PEG) as carriers for cefixime (a model drug). They observed that swelling in water was enhanced with increasing molecular weight of PEG. The CS/PEG hydrogels showed low swelling in neutral medium whereas maximum swelling in acidic and basic media was observed .
28. A method as claimed in Claim 26 or Claim 27, wherein said third polymeric material is said polycarboxylic acid polymer that is at least partially neutralised, said method comprising dispersing a polycarboxylic acid polymer in a solvent, optionally with a buffer agent, and adding base to at least partially neutralise the polycarboxylic acid polymer to form the inner coating preparation. coating the core using an inner coating preparation comprising a third polymeric material that is soluble in intestinal fluid or gastrointestinal fluid, in a solvent system to form an inner coated core and; coating the inner coated core with an outer coating preparation comprising a first polymeric material which is susceptible to attack by colonic bacteria and a second polymeric material which has a pH threshold of about pH 5 or above in a solvent system, to form an outer coated core, wherein the third polymeric material is selected from the group consisting of a polycarboxylic acid that is at least partially neutralised, and a non-ionic polymer, provided that, where the third polymeric material is a non-ionic polymer, said inner coating preparation comprises at least one additive selected from a buffer agent and a base.
Generally, sustained and controlled-release products provide a desired therapeutic effect, but fall short of diseases following biological rhythms. Circadian disorders such as hypertension, osteoarthritis, asthma etc., which require chronopharmacotherapy. PSDDS can effectively tackle this problem as it is modulated according to body’s circadian clock giving release of drug.
Zaino et al. prepared pH sensitive PEC hydrogels comprising of N -trimethyl chitosan (cationic component) and N -carboxymethyl chitosan (anionic component) to study the drug delivery profile of dexamethasone . Colon drug delivery can also be achieved using enteric polymers. As protein and peptide drugs are easily degraded by enzymes, which are more abundant in the small intestine than in the colon [40-44], colon is considered a target for more efficient delivery of enzyme-liable drugs. In a colon-targeted delivery system (CODES), tablets containing drugs and lactulose were first coated with an acid-soluble polymer and subsequently coated with an additional layer of enteric polymer [40-43].