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  • Masking the bitter taste of injectable lidocaine HCl formulation for dental procedures.

Masking the bitter taste of injectable lidocaine HCl formulation for dental procedures.

AAPS PharmSciTech (2014-11-02)
Yangjie Wei, Michael P Nedley, Sarit B Bhaduri, Xavier Bredzinski, Sai H S Boddu
ABSTRACT

Several attempts have been made to mask the bitter taste of oral formulations, but none have been made for injectable formulations. This study aims to mask the bitter taste of dental lidocaine HCl (LID) injection using hydroxypropyl-β-cyclodextrin (HP-β-CD) and sodium saccharin. Inclusion complexes of LID and HP-β-CD were prepared by the solution method in 1:1 and 1:2 M ratios. Inclusion complexes in solution were studied using phase solubility in phosphate buffer solutions (pH 8, 9, and 10). Freeze-dried inclusion complexes were characterized using differential scanning calorimetry (DSC), X-ray, Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and in vitro release. Injectable formulations were prepared using inclusion complexes and characterized for stability and for taste using an Alpha MOS ASTREE electronic tongue (ETongue). The association constants of HP-β-CD with lidocaine-free base and its ionized form were found to be 26.23 ± 0.00025 and 0.8694 ± 0.00045 M(-1), respectively. Characterization studies confirmed the formation of stable inclusion complexes of LID and HP-β-CD. Injectable formulations were found to be stable for up to 6 months at 4°C, 25°C, and 40°C. The taste evaluation study indicated that HP-β-CD (1:1 and 1:2 M ratios) significantly improved the bitter taste of LID injectable formulation. In conclusion, inclusion complex in the 1:1 M ratio with 0.09% sodium saccharin was considered to be optimum in masking the bitter taste of LID.

MATERIALS
Product Number
Brand
Product Description

Lidocaine, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
N,N′-Disuccinimidyl carbonate, purum, ≥95.0% (NMR)
Sigma-Aldrich
Lidocaine, analytical standard
Sigma-Aldrich
Lidocaine, powder
Supelco
Lidocaine, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
N,N′-Disuccinimidyl carbonate, ≥95%
USP
Lidocaine, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
(−)-Epinephrine (+)-bitartrate salt, solid
Supelco
Sodium Saccharin, analytical standard
Supelco
Saccharin Sodium, Pharmaceutical Secondary Standard; Certified Reference Material
USP
Epinephrine bitartrate, United States Pharmacopeia (USP) Reference Standard
Adrenaline tartrate with impurity A, European Pharmacopoeia (EP) Reference Standard
Saccharin sodium, European Pharmacopoeia (EP) Reference Standard