Key result
Cyclophilin binding assay yields ~2-fold higher cyclosporine concentrations than radioimmunoassay despite strong correlation.
Why the study?
Does the cyclophilin binding assay provide comparable cyclosporine concentration measurements to standard radioimmunoassay in blood samples?
Observational (n=100)
Does the cyclophilin binding assay provide comparable cyclosporine concentration measurements to standard radioimmunoassay in blood samples?
Effect estimate: r = 0.96
Absolute Event Rate: 520.4% vs 257.7%
p-value: p=<0.001
The cyclophilin binding assay correlates well with standard radioimmunoassay for monitoring blood cyclosporine but yields approximately two-fold higher concentration values.
Cyclosporine TDM requires assay-specific ranges to avoid dosing errors; leaves open outcome-based validation before routine adoption.
Cyclosporine binds with cyclophilin, an abundant protein found in almost all tissues, and the resulting complex interacts with calcineurin diminishing T-cell activation. Cyclophilin can be regarded as a cellular "receptor" for cyclosporine. Measuring cyclosporine binding to cyclophilin may offer a link between pharmacokinetics and pharmacodynamics that could improve monitoring of cyclosporine therapy. The authors investigated the feasibility of the cyclophilin binding assay and compared the results with a standard specific monoclonal radioimmunoassay in 100 blood samples taken for therapeutic drug monitoring. The results obtained with these methods were related closely with each other (r = 0.96; p < 0.001) but the mean (+/-SEM) concentrations were approximately two-fold higher in cyclophilin binding assay than in radioimmunoassay (520.4 +/- 49.9 ng/ml versus 257.7 +/- 28.6 ng/ml, respectively, p < 0.001). The shapes of the cyclosporine concentration versus time curves in two patients after a liver and heart transplantation, respectively, were similar after both methods but cyclophilin binding assay gave higher values than radioimmunoassay. Before firm conclusions on the clinical value of cyclophilin binding assay can be made, comparative studies in patients linking cyclosporine concentrations measured with cyclophilin binding assay and standard methods to the therapeutic outcome are needed.
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Huupponen et al. (1997) conducted an observational in Cyclosporine therapy monitoring (n=100). Cyclophilin binding assay vs. Standard specific monoclonal radioimmunoassay was evaluated on Blood cyclosporine concentration (r = 0.96, p=<0.001). The cyclophilin binding assay yielded approximately two-fold higher mean cyclosporine concentrations than radioimmunoassay (520.4 vs 257.7 ng/ml, p<0.001), despite a strong correlation (r=0.96).
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