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Issue 35, 2018, Issue in Progress
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Poly(allylamine)/tripolyphosphate coacervates enable high loading and multiple-month release of weakly amphiphilic anionic drugs: an in vitro study with ibuprofen

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Abstract

When synthetic polyamines, such poly(allylamine hydrochloride) (PAH), are mixed with crosslink-forming multivalent anions, they can undergo complex coacervation. This phenomenon has recently been exploited in various applications, ranging from inorganic material synthesis, to underwater adhesion, to multiple-month release of small, water-soluble molecules. Here, using ibuprofen as a model drug molecule, we show that these coacervates may be especially effective in the long-term release of weakly amphiphilic anionic drugs. Colloidal amphiphile/polyelectrolyte complex dispersions are first prepared by mixing the amphiphilic drug (ibuprofen) with PAH. Pentavalent tripolyphosphate (TPP) ions are then added to these dispersions to form ibuprofen-loaded PAH/TPP coacervates (where the strongly-binding TPP displaces the weaker-bound ibuprofen from the PAH amine groups). The initial ibuprofen/PAH binding leads to extremely high drug loading capacities (LC-values), where the ibuprofen comprises up to roughly 30% of the coacervate mass. Conversely, the dense ionic crosslinking of PAH by TPP results in very slow release rates, where the release of ibuprofen (a small, water-soluble drug) is extended over timescales that exceed 6 months. When ibuprofen is replaced with strong anionic amphiphiles, however (i.e., sodium dodecyl sulfate and sodium dodecylbenzenesulfonate), the stronger amphiphile/polyelectrolyte binding disrupts PAH/TPP association and sharply increases the coacervate solute permeability. These findings suggest that: (1) as sustained release vehicles, PAH/TPP coacervates might be very attractive for the encapsulation and multiple-month release of weakly amphiphilic anionic payloads; and (2) strong amphiphile incorporation could be useful for tailoring PAH/TPP coacervate properties.

Graphical abstract: Poly(allylamine)/tripolyphosphate coacervates enable high loading and multiple-month release of weakly amphiphilic anionic drugs: an in vitro study with ibuprofen

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Publication details

The article was received on 25 Mar 2018, accepted on 14 May 2018 and first published on 25 May 2018


Article type: Paper
DOI: 10.1039/C8RA02588F
RSC Adv., 2018,8, 19409-19419
  • Open access: Creative Commons BY-NC license
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    Poly(allylamine)/tripolyphosphate coacervates enable high loading and multiple-month release of weakly amphiphilic anionic drugs: an in vitro study with ibuprofen

    U. K. de Silva, Jennifer L. Brown and Y. Lapitsky, RSC Adv., 2018, 8, 19409
    DOI: 10.1039/C8RA02588F

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