Characterization of freeze-dried gallic acid/xyloglucan.
BACKGROUND
Tamarind seed xyloglucan (TSX) is generally used for drug delivery systems. Gallic acid (GA) possesses various pharmacological activities. It has a good solubility and bioavailability but short half-life.


OBJECTIVE
To prepare a sustained-release of GA to overcome its relatively short half-life. GA was blended with TSX and freeze-dried. The physicochemical properties of freeze-dried GA and freeze-dried GA/TSX were characterized, and the release profiles of GA from these freeze-dried samples were investigated.


METHODS
All freeze-dried samples were characterized by PXRD, spectroscopic and thermal analyses. The dissolution studies were performed according to the United States Pharmacopeia (USP) XXX.


RESULTS
According to FTIR, FT-Raman and (13)C CP/MAS NMR, the spectra of freeze-dried GA were similar to that of the anhydrous form. Nevertheless, DRIFTS and DSC were able to differentiate these two forms. The crystallinity of GA in the freeze-dried GA/TSX was the same as that of the freeze-dried GA. DSC indicates that there were interactions between GA and TSX. It was of interest that a freeze-dried sample with low amount of GA, 0.2% GA/1% TSX was mostly in an amorphous form. Moreover, all freeze-dried GA/TSX preparations demonstrated a sustained-release of GA compared to GA alone. The freeze-dried 1% GA/1% TSX provided the best sustained-release of GA of up to 240 min.


CONCLUSIONS
TSX could change a crystal form of a small molecule to a mostly amorphous form. It was of importance that the freeze-dried GA/TSX could effectively retard the release of GA. These samples may be able to overcome the limitation for the therapeutic use of GA due to its short biological half-life.
Department of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Nanotec-PSU Center of Excellence for Drug Delivery Systems, Prince of Songkla University , Hat-Yai , Thailand.
Namon
N
Hirun
Tanatchaporn
T
Sangfai
Vimon
V
Tantishaiyakul
D000975:Antioxidants / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D002152:Calorimetry, Differential Scanning; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D016503:Drug Delivery Systems; D005612:Freeze Drying; D005707:Gallic Acid / Q000008:administration & dosage* / Q000737:chemistry* / Q000493:pharmacokinetics; D005936:Glucans / Q000008:administration & dosage* / Q000737:chemistry* / Q000493:pharmacokinetics; D006207:Half-Life; D006801:Humans; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D012639:Seeds / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D029861:Tamarindus / Q000737:chemistry; D014961:X-Ray Diffraction; D014990:Xylans / Q000008:administration & dosage* / Q000737:chemistry* / Q000493:pharmacokinetics
D000975:Antioxidants; D003692:Delayed-Action Preparations; D005936:Glucans; D014990:Xylans; C029353:xyloglucan; D005707:Gallic Acid
DRIFTS; DSC; Dissolution; gallic acid; xyloglucan