Pharmacokinetic Modeling of Reversible Interconversion between Prednisolone and Prednisone

가역적상호대사과정 모델을 이용한 Prednisolone과 Prednisone의 약동학적 분석

  • Shin, Jae-Gook (Department of Pharmacology, Inje University College of Medicine and Clinical Pharmacology Center/Pusan Paik Hospital) ;
  • Yoon, Young-Ran (Department of Pharmacology, Inje University College of Medicine and Clinical Pharmacology Center/Pusan Paik Hospital) ;
  • Cha, In-June (Department of Pharmacology, Inje University College of Medicine and Clinical Pharmacology Center/Pusan Paik Hospital) ;
  • Jang, In-Jin (Department of Pharmacology, Seoul National University College of Medicine and Clinical Pharmacology Unit/SNUH) ;
  • Lee, Kyung-Hoon (Department of Pharmacology, Seoul National University College of Medicine and Clinical Pharmacology Unit/SNUH) ;
  • Shin, Sang-Goo (Department of Pharmacology, Seoul National University College of Medicine and Clinical Pharmacology Unit/SNUH)
  • 신재국 (인제대학교 의과대학 약리학교실 및 부산백병원 임상약리센터) ;
  • 윤영란 (인제대학교 의과대학 약리학교실 및 부산백병원 임상약리센터) ;
  • 차인준 (인제대학교 의과대학 약리학교실 및 부산백병원 임상약리센터) ;
  • 장인진 (서울대학교 의과대학 약리학교실 및 서울대학교병원 임상약리실) ;
  • 이경훈 (서울대학교 의과대학 약리학교실 및 서울대학교병원 임상약리실) ;
  • 신상구 (서울대학교 의과대학 약리학교실 및 서울대학교병원 임상약리실)
  • Published : 1996.09.30

Abstract

Pharmacokinetics of prednisolone and prednisone undergoing reversible interconversion were analyzed from the model including this metabolic process. Blood samples were drawn serially upto 12 hours after I,V. bolus injection of 1 mg/kg prednisolone sodium phosphate and prednisone into 8 dogs as a crossover manner. Plasma concentrations of those two steroids were simultaneously measured with the method of HPLC. After injection, plasma concentrations of administered prednisolone and prednisone were declined with a biexponential pattern and their metabolic partner was rapidly formed. Plasma concentrations of those metaboite were decayed in parallel with their parent steroids throught the elimination phase. Apparent clearances of prednisolone and prednisone were $11.1{\pm}2.0\;ml/min/kg$ and $45.9{\pm}6.4\;ml/min/kg$, and they were underestimated by 29.4% and 33.6% compared to their real clearances$(15.7{\pm}4.4\;and\;69.2{\pm}17.7\;ml/min/kg)$ estimated using reversible interconversion model. Apparent volume of distribution of prednisolone$(1.32{\pm}0.43\;L/kg)$ and prednisone$(4.81{\pm}2.75\;L/kg)$ were overestimated by 53.5 and 52.7% and were compared to the real volumes $(0.86{\pm}0.30\;and\;3.15{\pm}2.13\;L/kg)$. Mean residence time of prednisolone$(2.0{\pm}0.61\;h)$ and prednisone$(1.74{\pm}0.74\;h)$ were much longer than the real sojourn time$(0.93{\pm}0.26\;and\;0.88{\pm}0.54\;h)$. Essential clearances In the reversible interconversion were greater as following orders: $Cl_{21}$(44.3 ml/min/kg) > $Cl_{20}$(24.2 ml/min/kg) > $Cl_{12}$ (7.9 ml/min/kg) > $Cl_{10}$(7.8 ml/min/kg). Estimated mean values of RF, EE, $%X^1_{ss}$ and $RHO^2_1$ were $0.31{\pm}0.10$, $1.49{\pm}0.23$, $69.3{\pm}16.7%$ and $0.65{\pm}0.10$, respectively. These results suggested that true pharmacokinetic parameters estimated from the model including reversible interconversion were significantly different from the apparent parameters estimated from the conventional mamillary model, and disposition of these two steroids seemed to be well explained by the model including reversible interconversion.

Keywords