초록
This randomized, single-blind, two-sequence, two-period crossover study in 24 healthy volunteers with a 2-week washout interval compared pharmacokinetics of two salt forms of amlodipine formulations, the newly developed formulation (amlodipine orotate, $Orodipine^{(R)}$, Dong-A Pharmaceutical Company, Limited, Korea) to increase the dissolution rate at higher gastric pH conditions and the original formulation (amlodipine besylate, $Norvasc^{(R)}$, Pfizer Incorporated, Korea). Methods: Plasma samples were obtained over 144 h after a single oral dose of 10 mg amlodipine, two tablets for each formulation. Plasma amlodipine concentrations were analyzed by combined liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS) with positive ion electrospray ionization (ESI) using multiple reaction monitoring (MRM). From the amlodipine plasma concentration versus time curves, the amlodipine pharmacokinetic parameters were determined by non-compartmental method. Results: Mean of area under the plasma amlodipine concentration-time curve from time 0 to time infinity $(AUC_{0-{\infty}})$ of Orodipine was $336ng{\cdot}h/mL$ (coefficient of variation (CV)=31.3%) and that of $Norvasc^{(R)}$ was $329ng{\cdot}h/mL$ (CV=38.3%). Mean of maximum observed plasma amlodipine concentration $(C_{max})$ of Orodipine was 6.89 ng/mL (CV=25.8%) and that of $Norvasc^{(R)}$ was 6.46 ng/mL (CV=32.0%). The percent ratios of 90% confidence intervals of $Orodipine^{(R)}/Norvasc^{(R)}$ were $99{\sim}124%\;for\;(C_{max})\;and\;94{\sim}118%\;for\;AUC_{0-{\infty}}$ and the means of terminal elimination half-life $(t_1/2{\beta})$ of amlodipine were 44.0 h (CV=17.5%) for $Orodipine^{(R)}$ and 42.6 h (CV=16.7%) for $Norvasc^{(R)}$ respectively. Conclusion: Since amlodipine orotate and amlodipine besylate showed similar pharmacokinetic characteristics, alteration of the salt form did not affect the pharmacokinetics of amlodipine.