Evidence of Different Pharmacokinetics Including Relationship among <i>AUC</i>, Peak, and Trough Levels between Cyclosporine and Tacrolimus in Renal Transplant Recipients Using New Pharmacokinetic Parameter&mdash;Why Cyclosporine Is Monitored by <i>C</i>₂ Level and Tacrolimus by Trough Level&mdash;

Abstract

Cyclosporine (CYA) and tacrolimus (TAC) are calcineurin inhibitors with similar action mechanisms. However, there have not been any detailed reports on the pharmacokinetic differences of relationship among are under the concentration time curve (AUC), peak concentration (C p ), and trough concentration (C t ), regarding CYA and TAC after oral administration in a controlled group. 1) AUC of CYA has been reported to be associated with clinical efficacy. [2][3][4][5] On the other hand, the relationship between AUC of TAC and the clinical efficacy of TAC has not been evaluated precisely. However, it is generally thought that AUC is the most reliable pharmacokinetic parameter to predict the clinical efficacy of calcineurin inhibitors including TAC. CYA blood concentration is often monitored by blood concentration at 2 h after administration (C 2 ) to be more significantly associated with AUC, 6) and TAC blood concentration is monitored by C t . It has yet to be explained why only AUC of CYA correlates more significantly with C 2 , and we could not clearly account for why the monitoring timings differ between CYA and TAC. Therefore, we investigated this issue to compare the blood concentration curve patterns and pharmacokinetic parameters of CYA and TAC in renal transplant recipients by using new pharmacokinetic parameters such as area under the trough level (AUTL) and area above the trough level (AATL). These parameters are parts of AUC and are dependent on C t and C p , respectively as described later. MATERIALS AND METHODSPatients Twelve hours of monitoring of CYA and TAC blood concentrations was performed on 20 patients who were administered a CYA microemulsion formulation at 41.8Ϯ 20.5 (meanϮS.D.) d after renal transplantation and on 24 patients who were administered TAC at 41.4Ϯ21.4 d after transplantation. This monitoring was routinely carried out once before hospital discharge. The CYA-administrated patients consisted of 11 males and 9 females aged 42.7Ϯ1.0 (meanϮS.D.) years, and the mean (S.D.) body weight of these patients was 53.5Ϯ10.0 kg. The TAC-administrated patients consisted of 15 males and 9 females aged 46.5Ϯ11.3 years, and their mean body weight was 52.3Ϯ9.9 kg ( Table 1). None of the patients had digestive or liver dysfunction, which may affect the absorption or metabolism of CYA or TAC. All patients received a triple immunosuppressive-drug regimen, which consisted of calcineurin inhibitors (CYA or TAC), methylprednisolone, and either mycophenolate mofetil or azathioprine. Other drugs known to affect the pharmacokinetics of CYA or TAC were not administered to these patients. Informed consent was obtained from all patients included in this study. The clinical efficacy of calcineurin inhibitors administered to renal transplant patients is considered to be a strong function of the area under the concentration time curve (AUC). Interestingly, monitoring timings of blood concentrations for two similar calcineurin inhibitors, cyclosporine (CYA; Neoral ® ) and tacrolimus (TAC; Prograf ® ) are different. ...

The effect of Maintenance Treatment with Twice-daily or Prolonged Once-daily Tacrolimus Formulation on Visual Evoked Potentials in Stable Kidney Transplant Recipients

“…However, it has been shown that AUC-guided tacrolimus dosing prevents progressive systemic overexposure in KTRs [ 30 ]. Moreover, due to specific pharmacokinetic relationships among AUC, peak and trough levels, the blood trough level is the preferable measure for tacrolimus therapy monitoring [ 31 ].…”

Hospital Pharmacometrics for Optimal Individual Administration of Antimicrobial Agents for Anti-methicillin-resistant <i>Staphylococcus aureus</i> Infected Patients

“…5) Methicillin-resistant Staphylococcus aureus (MRSA) causes severe infections, has a high mortality rate, and leads to prolonged hospitalization; therefore, the control and treatment of this infection is one of the most major problems for medical workers. [6][7][8] Nosocomial infections and community-acquired MRSA infections are growing public health concerns. Six antimicrobial agents have been clinically approved for the treatment of MRSA in Japan as of December 2020.…”