Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1997-04-24
1999-07-27
Mosley, Terressa
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
424486, 528176, C08G 6300
Patent
active
059291966
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns new polyesters consisting of a polyol containing substituents with electrolyte properties with polymeric hydroxycarboxylic acid esters, their production and use.
In particular, it concerns new branched-chain esters from a polyol containing substituents with electrolyte properties with groups consisting of polylactic or copolylactic-glycolic acid, their production and use as a matrix material for depot forms containing pharmacologically active substances.
BACKGROUND OF THE INVENTION
Depot forms can be administered in different ways, for example, orally, parenterally, ocularly, pulmonally or by sprinkling in wounds. Depot forms, also referred to as parenteral slow-release forms, appropriate for parenteral administration are of particular interest.
Parenteral slow-release forms can be formulated as microparticles, implants and fibers. Microparticles are of special interest, since, because of their limited dimensions, they can be suspended in an appropriate medium and administered comparatively painlessly by means of a syringe via an injection needle with limited diameter.
Such formulations are of interest for all pharmacologically active substances if long-persisting, uniform systemic or local active ingredient concentrations are desired. They are particularly advantageous for active ingredients that are destroyed or insufficiently resorbed during oral administration and can only be applied parenterally. This is the case, for example, in pharmacologically active peptides, like peptide hormones or proteins.
Of special interest are interleukins (IL-1 to IL-15), interferons (IFN), neurotrophins (NT-1 to NT-3), colony-stimulating factors (CSF), epidermal growth factors (EGF), neuronal growth factors, prolactin, luteinizing-hormone-releasing hormone (LH-RH), insulin, somatostatin, glucagon, gastrin, pentagastrin, urogastrone, calcitonin, secretin, enkephalins, endorphins, angiotensins, renin, bradykinin, tyrocidine, gramicidins, erythropoetin (EPO), angiopeptin, hirudin, oxytocin, vasopressin, calcitonin-gene-related peptide (CGRP), brain-derived growth factors (BDGF), their synthetic analogs and modifications, as well as their pharmacologically active fragments.
Generally the most constant possible active ingredient release over the entire release period is aimed for in parenteral slow-release formulations. Release of the active ingredients from depot forms made of biodegradable matrix polymers is dictated by their diffusion rate in the polymer and their degradation rate. To avoid accumulation of the matrix polymer during successive application this should be degraded as fully as possible after completion of active ingredient release.
Biodegradable matrix polymers for active ingredient embedding have already been described in 1973 in U.S. Pat. No. 3,773,919. Polymers from hydroxycarboxylic acids, especially lactic and/or glycolic acid were proposed. Polymers from lactic and/or glycolic acid are hydrolyzed in the body to lactic and/or glycolic acid, which are further metabolized to CO.sub.2 and water and are therefore particularly usable in the production of parenteral slow-release forms.
Depot forms from polylactic acid (PLA) or polylactic-glycolic acid (PLGA), especially microparticles, generally exhibit a multiphase release trend and initially display a sharply increased release because of active ingredient present on the surface. This is followed by a phase of sharply reduced or nonexistent release, especially in peptide active ingredients, which is then followed by later active ingredient liberation supported by polymer mass degradation. Polymer residues are still present at the time of completion of active ingredient liberation.
EP 0 058 481 B1 describes the use of a mixture of PLGA having different molecular weights. Liberation is supposed to be linearized by this and the degradation rate adjusted to the liberation period. Use of such polymer mixtures, however, imposes high requirements on the hydrolysis stability of the active ingredient and they are not su
REFERENCES:
patent: 3773919 (1973-11-01), Boswell et al.
patent: 4937254 (1990-06-01), Sheffield et al.
Kissel Thomas
Li Youxin
Mosley Terressa
Schwarz Pharma AG
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