Validation of a capillary electrophoresis method for determination of 5-aminolevulinic acid and degradation products

Bunke, A.; Schmid, Helene; Burmeister, G.; Merkle, Hans P.; Gander, Bruno

doi:10.1016/s0021-9673(00)00334-4

Cited by 27 publications

(22 citation statements)

References 16 publications

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“…[10] This degradation mechanism has been subject to much elucidation. [11] Being an a-aminoketone, ALA dimerises readily in alkaline conditions to form 3,6-dihydropyrazine 2,5-dipropionic acid (DHPY), porphobilinogen and pseudo-porphobilinogen via an open-chain dimeric ketimine. DHPY is formed initially and is then oxidised to pyrazine 2,5-dipropionic acid (PY), which is the major degradation product in aerated solutions.…”

Section: Introductionmentioning

confidence: 99%

Aminolevulinic acid-loaded Witepsol microparticles manufactured using a spray congealing procedure: implications for topical photodynamic therapy

Al-Kassas¹,

Donnelly²,

McCarron³

2009

j pharm pharmacol

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Objectives The aim was to enhance aminolevulinic acid (ALA) stability by incorporation into low-melting microparticles prepared using a spray congealing procedure and to evaluate temperature-triggered release, allowing topical bioavailability following melting at skin temperature. Methods ALA-loaded Witepsol microparticles were prepared using a novel spray congealing technique. Entrapment efficiency was compared with conventional emulsionbased methods and modelled drug release profiles determined using a membrane separation technique. Raised receiver medium temperature was used to determine triggered release. Bioavailability and lipid-mediated enhancement of ALA penetration were determined in excised murine skin. Key findings ALA-loaded Witepsol microparticles were spherical, with a mean diameter of 20 mm. Loading and stability studies demonstrated effective encapsulation, ranging from 91% to 100%, with no evidence of degradation to pyrazine derivatives. ALA release correlated with dissolution medium temperature, triggered at temperatures close to that of skin. Results suggested that molten Witepsol enhanced cutaneous permeation, whereas incorporation of microparticles in a semi-solid vehicle attenuated ALA penetration. Optimal use was direct application under occlusion. Conclusions Spray congealing is superior to the emulsion-based procedures with respect to encapsulation efficiency of ALA in Witepsol matrices, providing temperature-triggered release, enhanced stability and improved penetration of ALA through keratinised skin. These features could improve ALA delivery to superficial lesions as part of photodynamic therapy.

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Section: Introductionmentioning

confidence: 99%

Aminolevulinic acid-loaded Witepsol microparticles manufactured using a spray congealing procedure: implications for topical photodynamic therapy

Al-Kassas¹,

Donnelly²,

McCarron³

2009

j pharm pharmacol

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show abstract

“…Other methods based on gas-liquid chromatography with electron-capture detection [17] or capillary electrophoresis coupled to UV detection [18] have been proposed, but the instruments they rely on are not readily available in most laboratories. Thus the most common methods to quantify ALA involve its detection after chemical derivatisation.…”

Section: Introductionmentioning

confidence: 99%

Quantitative determination of 5-aminolaevulinic acid and its esters in cell lysates by HPLC-fluorescence

Giuntini

Bourré

MacRobert

et al. 2008

Journal of Chromatography B

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“…ALA belongs to the class of alpha amino ketones with a weak chromophoric carbonyl group and consequently is unsuitable for quantification by conventional ultraviolet (UV) absorption spectroscopy. A number of methods have been used for ALA quantification including ion exchange chromatography [12] and capillary electrophoresis [13]. HPLC is one of the most routine tools for pharmaceutical analysis in both industrial and university laboratories.…”

Section: Introductionmentioning

confidence: 99%

Liquid chromatography assay for 5-aminolevulinic acid: Application to in vitro assessment of skin penetration via Dermaportation

Namjoshi

Caccetta

Edwards³

et al. 2007

Journal of Chromatography B

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Validation of a capillary electrophoresis method for determination of 5-aminolevulinic acid and degradation products

Cited by 27 publications

References 16 publications

Aminolevulinic acid-loaded Witepsol microparticles manufactured using a spray congealing procedure: implications for topical photodynamic therapy

Aminolevulinic acid-loaded Witepsol microparticles manufactured using a spray congealing procedure: implications for topical photodynamic therapy

Quantitative determination of 5-aminolaevulinic acid and its esters in cell lysates by HPLC-fluorescence

Liquid chromatography assay for 5-aminolevulinic acid: Application to in vitro assessment of skin penetration via Dermaportation

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