Pharmacokinetic Comparison of Two Formulations Containing Silymarin : Legalon cap. $140^{\circledR}$vs. a Generic Formulation

레가론캅셀 $140^{\circledR}$ 및 국내 generic 제형의 약동학적 특성에 관한 비교 연구

  • Lim, Hyeong-Seok (Department of Pharmacology, Seoul National University College of Medicine, Clinical Pharmacology Unit and Clinical Trial Center, Seoul National University Hospital) ;
  • Yi, So-Young (Department of Pharmacology, Seoul National University College of Medicine, Clinical Pharmacology Unit and Clinical Trial Center, Seoul National University Hospital) ;
  • Cho, Joo-Youn (Department of Pharmacology, Seoul National University College of Medicine, Clinical Pharmacology Unit and Clinical Trial Center, Seoul National University Hospital) ;
  • Bae, Kyun-Seop (Department of Pharmacology, Seoul National University College of Medicine, Clinical Pharmacology Unit and Clinical Trial Center, Seoul National University Hospital) ;
  • Yu, Kyung-Sang (Department of Pharmacology, Seoul National University College of Medicine, Clinical Pharmacology Unit and Clinical Trial Center, Seoul National University Hospital) ;
  • Yim, Dong-Seok (Department of Pharmacology, Gachon Medical School) ;
  • Jang, In-Jin (Department of Pharmacology, Seoul National University College of Medicine, Clinical Pharmacology Unit and Clinical Trial Center, Seoul National University Hospital) ;
  • Shin, Sang-Goo (Department of Pharmacology, Seoul National University College of Medicine, Clinical Pharmacology Unit and Clinical Trial Center, Seoul National University Hospital)
  • 임형석 (서울대학교 의과대학 약리학교실,서울대학교병원 임상약리실,서울대학교병원 임상의학연구소 임상시험센터) ;
  • 이소영 (서울대학교 의과대학 약리학교실,서울대학교병원 임상약리실,서울대학교병원 임상의학연구소 임상시험센터) ;
  • 조주연 (서울대학교 의과대학 약리학교실,서울대학교병원 임상약리실,서울대학교병원 임상의학연구소 임상시험센터) ;
  • 배균섭 (서울대학교 의과대학 약리학교실,서울대학교병원 임상약리실,서울대학교병원 임상의학연구소 임상시험센터) ;
  • 유경상 (서울대학교 의과대학 약리학교실,서울대학교병원 임상약리실,서울대학교병원 임상의학연구소 임상시험센터) ;
  • 임동석 (가천의대 가천길병원 약리학과) ;
  • 장인진 (서울대학교 의과대학 약리학교실,서울대학교병원 임상약리실,서울대학교병원 임상의학연구소 임상시험센터) ;
  • 신상구 (서울대학교 의과대학 약리학교실,서울대학교병원 임상약리실,서울대학교병원 임상의학연구소 임상시험센터)
  • Published : 2001.06.30

Abstract

Background : Silymarin formulations show low bioavailability due to its poor solubility. Therefore, developing a formulation which could improve bioavailability was a major issue. In Korea, there are many kinds of silymarin-containing formulations, including Legalon cap. $140^{\circledR}$. We compared the pharmacokinetic characteristics of a generic silymarin formulation developed by H company with those of Legalon cap. $140^{\circledR}$. and speculated on the clinical implications. Methods : The study was conducted as a open-labeled, randomized, 2-way crossover Latin square design in 16 healthy subjects. Subjects were separated into two groups, A and B. Subjects in group A were administered a generic formulation orally, and 1 week later they were administered Legalon cap. $140^{\circledR}$. Subjects in group B were administered the drugs in opposite sequence in the same manner. Dosage administered was 60 mg as silibinin. Serial blood samples were collected till 24 hours after the drug administration. Plasma concentrations of silibinin diastereomers were assayed by HPLC and total silibinin concentrations were obtained. Pharmacokinetic parameters of the two formulations were analyzed by noncompartmental methods. We tested the sequence effect, period effect and differences of parameters between the two formulations by ANOVA. The pharmacokinetic characteristics of two test formulations were compared by 90% confidence intervals for ratios of $AUC_{0-\infty}$ and $C_{max}$, and the other kinetic parameters by student t-test. Results : Mean $AUC_{0-\infty}$ and $C_{max}$ of the generic formulation were 1.46 and 3.06 times higher than those of Legalon cap. $140^{\circledR}$, respectively $(AUC_{0-\infty}\;:\;3766{\pm}1475\;vs.\;2580{\pm}863\;ng{\cdot}hr/mL,\;C_{max}\;:\;1639{\pm}499\;vs.\;535{\pm}181\;ng/mL\;;\;generic\;vs.\;Legalon\;cap.\;140^{\circledR},\;mean\;{\pm}\;SD)$. The differences of $AUC_{0-\infty}$ and $C_{max}$ were statistically significant (p<0.001). $t_{max}$, MRT, and terminal half-life of the two drugs were also statistically different $(t_{max}\;:\;0.73{\pm}0.22\;vs\;1.67{\pm}0.98\;hr,\;MRT\;:\;5.38{\pm}1.65\;vs\;6.11{\pm}1.41\;hr,\;t_{1/2}\;:\;5.48{\pm}1.71\;vs.\;4.47{\pm}1.75\;hr,\;a\;generic\;vs.\;Legalon\;cap.\;140^{\circledR})$. The mean of individual relative bioavailability $(generic/Legalon\;Cap.\;140^{\circledR})$ was 1.46, and the 90% confidence interval was 1.31-1.62. The mean ratio of $C_{max}$ $(generic/Legalon\;Cap.\;140^{\circledR})$ was 3.1, and the 90% confidence interval was 2.47-3.82. Conclusion : The $AUC_{0-\infty}$ and $C_{max}$ of the new generic drug were significantly greater then those of Legalon cap. $140^{\circledR}$. The generic drug was rapidly absorbed, and the increase in oral bioavailability was primarily due to the increase in the early phase absorption. The two formulations were not bioequivalent, and the therapeutic equivalence needs to be evaluated. The clinical implications of greater $AUC_{0-\infty}$ and $C_{max}$ should be investigated by additional clinical studies. The dosage of the generic has not been established by clinical studies, in contrast to that of Legalon Cap. $140^{\circledR}$.

Keywords