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Joshi, Rajashree; Arora, Vikram; Desjardins, John; Robinson, Dennis H.; Himmelstein, Kenneth J.; Iversen, Patrick L.

doi:10.1023/a:1011979505697

Cited by 19 publications

(6 citation statements)

References 9 publications

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“…Aqueous solutions of P407 above a concentrations of about 20% (w/w) are liquid when refrigerated, but gel upon warming 11. However, application of concentrated polymer solutions (>16%) in drug delivery may be disadvantageous as it changes the osmolality of the formulation, kinetics of gelation, and causes discomfort in ophthalmic applications due to vision blurring and crusting 12. It has been shown that such concentration cause notable toxicity and increased cholesterol and triglycerides levels in plasma after intraperitoneal injection in rats 13.…”

Section: Introductionmentioning

confidence: 99%

In situ gel forming systems of poloxamer 407 and hydroxypropyl cellulose or hydroxypropyl methyl cellulose mixtures for controlled delivery of vancomycin

Talasaz¹,

Ghahremankhani²,

Moghadam³

et al. 2008

J of Applied Polymer Sci

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Poloxamers are a family of triblock copolymers consisting of two hydrophilic blocks of polyoxyethylene separated by a hydrophobic block of polyoxypropylene, which form micelles at low concentrations and form clear thermally reversible gels at high concentrations. The objective of this study was to develop an in situ gel forming drug delivery system for vancomycin using the minimum possible ratio of poloxamer 407 (P407). Decreasing the concentration of poloxamer could reduce the risk of hypertriglyceridemia induction. Different additives were added to the poloxamer formulations. It was observed that among different additives, hydroxypropyl methyl cellulose (HPMC) and hydroxypropyl cellulose (HPC) can decrease poloxamer concentration required to form in situ gelation from 18 to 10%. The dynamic viscoelastic properties of the samples were determined. Both the storage modulus and the loss modulus of the samples increased abruptly as the temperature passed a certain point. The gelling temperature was in the order of P407 : HPC (10 : 10 w/w) < P407 : HPMC (10 : 10 w/w) < P407 : HPMC (15 : 5 w/w) < P407 : HPC (15 : 5 w/w). Drug release rate could be controlled by changing the type and ratio of additives as well as the amount of drug loaded. It can be concluded that combining P407 and cellulose derivatives could be a promising strategy for preparation of thermally reversible in situ gel forming delivery systems with low poloxamer concentration.

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Section: Introductionmentioning

confidence: 99%

In situ gel forming systems of poloxamer 407 and hydroxypropyl cellulose or hydroxypropyl methyl cellulose mixtures for controlled delivery of vancomycin

Talasaz¹,

Ghahremankhani²,

Moghadam³

et al. 2008

J of Applied Polymer Sci

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“…Hence, for a model study, we have chosen the hydroxypropylcellulose (HPC) as a proton-accepting polymer and poly(acrylic acid) (PAA) as a proton-donating polymer to study how the complexation between these two polymers affect the LCST of the HPC polymer under various conditions. Our literature survey shows that studies of the structure and properties of interpolymer complexes between poly(acrylic acid) and nonionic cellulose ethers have been reported. − Specifically, Budtova and co-workers 15-17 investigated the formation and properties of the interpolymer complexation between PAA and cellulose ethers including hydroxyethylcellulose (HEC) and methylcellulose (MC). Their experimental results showed that the mixtures of the cellulose ethers and nonionized PAA in aqueous solution formed interpolymer complexes due to hydrogen bonding.…”

Section: Introductionmentioning

confidence: 99%

“…Our literature survey shows that studies of the structure and properties of interpolymer complexes between poly(acrylic acid) and nonionic cellulose ethers have been reported. [15][16][17][18][19][20][21][22][23] Specifically, Budtova and co-workers [15][16][17] investigated the formation and properties of the interpolymer complexation between PAA and cellulose ethers including hydroxyethylcellulose (HEC) and methylcellulose (MC). Their experimental results showed that the mixtures of the cellulose ethers and nonionized PAA in aqueous solution formed interpolymer complexes due to hydrogen bonding.…”

Section: Introductionmentioning

confidence: 99%

Phase Transition Behavior of Hydroxypropylcellulose under Interpolymer Complexation with Poly(acrylic acid)

Schwartz

2002

Macromolecules

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The phase transition behavior of hydroxypropylcellulose (HPC) under interpolymer complexation with poly(acrylic acid) (PAA) has been studied by turbidity and laser light scattering measurements. It has been found that the lower critical solution temperature (LCST) of the HPC was drastically reduced after adding 1 wt % of PAA into the HPC solution. The LCST of the HPC/PAA complexes decreased with the increase of the molecular weight of either the HPC or the PAA. The driving force shifting the LCST is attributed to the hydrogen bonding and hydrophobic interaction of the macromolecules. As the pH value increases from at 4.0 to 6.0, the LCST of the HPC−PAA complex decreases. This may be due to the salt effect of the polyelectrolyte on the nonionic polymer. The HPC/PAA complexation has been observed even at very dilute solution of 1.6 × 10-5 g/mL at pH = 3.2. The study of complexation between the HPC and the PAA leads to a new method for synthesis of surfactant-free microgels at room temperature. The resultant microgels swell and collapse at the pH value higher and lower than the pK α value of the PAA, respectively.

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“…The high concentrations of these polymers may cause unfavorable interactions during use under physiological conditions. While US Patent 5252318 [28] reports reversible gelling compositions which are made of physical blends of a pHsensitive gelling polymer (such as a cross-linked polyacrylic acid) and a temperature-sensitive gelling polymer (such as methyl cellulose or block copolymers of polyoxoethylne and polyoxopropylene). This patent also describes a gel system from the mixtures of polyoxyethylene and polyoxypropylene condensed with ethylenediamine.…”

Section: Thermo-responsive Pulsatile/ Triggered Releasementioning

confidence: 99%

Stimuli-induced Pulsatile or Triggered Release Delivery Systems for Bioactive Compounds

Anal¹

2007

EMI

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As is frequently found in the living body, many vital functions are regulated by pulsed or triggered release of bioactive substances at a specific site and time. Thus it is important to develop new drug delivery devices to achieve pulsed delivery of a certain amount of drugs in order to mimic the function of the living systems to minimize the undesired side effects. The pulsed or triggered delivery systems are designed to alter their rate of drug delivery in response to stimuli such as changes in a specific molecule, a magnetic or electric field, temperature, light or mechanical forces. Such systems are suitable for the release of therapeutics that benefit from non-constant plasma concentrations. In this article, several types of drug delivery systems which cause the pulsed or triggered release of bioactive compounds due to certain external stimuli, mostly focuses on thermally-, electrically-and magnetically-induced release are described in detail. The recent patents on various delivery systems which release the active compounds only with the external stimuli are described in detail.

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Untitled

Abstract: The IPC solutions exhibit phase transformation in vivo. and demonstrate no evidence of toxicity. The pharmacological effects observed from the of release of 3A2-ATG-psODNs suggest that the formulation can entrap, protect, and sustain the delivery of macromolecules. .

Cited by 19 publications

References 9 publications

In situ gel forming systems of poloxamer 407 and hydroxypropyl cellulose or hydroxypropyl methyl cellulose mixtures for controlled delivery of vancomycin

In situ gel forming systems of poloxamer 407 and hydroxypropyl cellulose or hydroxypropyl methyl cellulose mixtures for controlled delivery of vancomycin

Phase Transition Behavior of Hydroxypropylcellulose under Interpolymer Complexation with Poly(acrylic acid)

Stimuli-induced Pulsatile or Triggered Release Delivery Systems for Bioactive Compounds

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