Problems of cyclosporine absorption profiling using C2-monitoring

Area of Science:

• Pharmacokinetics and Therapeutic Drug Monitoring
• Transplant Medicine
• Immunosuppression Management

Background:

• Cyclosporine (CsA) is a critical immunosuppressant in organ transplantation.
• Optimizing CsA exposure is vital for graft survival and minimizing toxicity.
• C2 monitoring, a measure of CsA concentration at 2 hours post-dose, is proposed for therapeutic drug monitoring.

Purpose of the Study:

• To validate the clinical utility of C2 monitoring for optimizing CsA dosing in de-novo transplant recipients.
• To assess the achievement of target C2 levels and identify factors influencing CsA absorption.
• To evaluate the correlation between C2 levels, CsA toxicity, and patient/graft outcomes.

Main Methods:

• A prospective study involving 41 de-novo transplant patients treated with CsA microemulsion, mycophenolate sodium, steroids, and basiliximab.
• Regular monitoring of C2 and C0 (trough concentration) levels, along with CsA dosage adjustments.
• Assessment of patient and graft survival, rejection rates, and CsA-related toxicity over 6 months.

Main Results:

• After 6 months, patient and graft survival was 98% with a 19% rejection rate.
• In the first week, only 19% of patients achieved C2 > 1500 ng/ml despite increased CsA dose.
• By day 14, 63% reached C2 > 1500 ng/ml with decreased CsA dose; 35% showed poor absorption (high C0, low C2) and experienced CsA toxicity.

Conclusions:

• C2 monitoring may aid in individualizing CsA exposure estimation but has limitations.
• Many patients struggle to reach proposed C2 levels, indicating absorption variability.
• C2 monitoring alone may not detect CsA toxicity, and lower target levels might be adequate when using basiliximab and mycophenolate sodium.