Whole blood is the preferred matrix for CsA measurement, primarily for analytical reasons. It is inappropriate to multiply CsA concentrations measured in one matrix by a correction factor in an attempt to estimate values in another matrix. EDTA is preferred over heparin as anticoagulant, because clots, which result in an inhomogeneous sample, do not usually form with the former but can with the latter, especially in samples that stand for prolonged periods of time before analysis or that are subjected to freezing and thawing. The method for measurement of CsA should be specific. This is consistent with recommended analytical laboratory practice for other monitored drugs[e.g., tricyclic antidepressants (149), digoxin (150), and phenytoin (151)]. Appropriately validated HPLC methods measure CsA specifically, and this appears to be true of the new generation of monoclonal immunoassays that currently are under evaluation (22, 148, 152). Large concentrations of metabolites 17 and 1 are present in the blood and renal tissue of kidney-transplant patients. These metabolites have in vitro immunosuppressive activity. Their toxicity is unknown. The clinical significance of the contribution of the metabolites to immunosuppression or toxicity, and whether or not to monitor them in addition to CsA, all requires further study. Should these or other metabolites be shown to be clinically significant, specific assays for their measurement are recommended. It is recommended that laboratories measuring CsA participate in an accredited proficiency-testing program that can provide feedback about the accuracy and reproducibility of their methods. As is true for other commonly monitored drugs, CsA concentrations need to be interpreted in conjunction with other laboratory data and clinical considerations. The usual transplant patient during the immediate post-operative period should be monitored at the least every other day. However, in special transplant populations during the early post-transplant period (liver- and heart-transplant patients), more frequent monitoring may be necessary. The clinical significance of long-term routine CsA monitoring after transplantation has yet to be established. However, it can be anticipated that periodic checks will be of value, both as a measure of compliance and because of the potential for clinically significant drug interactions if concomitant drug therapy is altered.
|Original language||English (US)|
|Number of pages||20|
|State||Published - Jan 1 1987|
All Science Journal Classification (ASJC) codes
- Clinical Biochemistry
- Biochemistry, medical