cyclosporin A in blood

Indications

• therapeutic drug monitoring, cyclosporine A
  • organ transplantation
  • rheumatoid arthritis
  • inflammatory bowel disease
  • severe asthma

Reference interval

• trough < 300 ng/mL
• renal tranplantation (trough)
  • 200-300 ng/mL (1st few weeks)
  • 50-75 ng/mL (after 3 months)

Principle

The ABBOTT TDx Cyclosporine Monoclonal Antibody Whole Blood assay is an -in vitro- reagent system for the quantitative measurement of cyclosporine (Sandimmune Cyclosporine A) in human whole blood samples.

The TDx Cyclosporine Monoclonal Whole Blood assay utilizes Fluorescence Polarization Technology. The antigen in the specimen competes with the antigen-tracer in the reagent for binding sites in the antibody. When the amount of antigen in the unknown specimen is high, more antigen will bind to the antibody leaving the antigen-tracer free in solution, i.e., small molecules rotating rapidly. When the amount of antigen in the specimen is low, less will bind to the antibody, & more antigen-tracer will bind, i.e., large molecule rotating slowly.

Clinical significance

Cyclosporine may be administered IV or orally. Absorption from the gastrointestinal tract is variable, unpredictable & incomplete. Bio-availability increases during treatment so that oral doses must be gradually reduced in order to maintain a constant cyclosporine concentration is the blood. Cyclosporine is almost completely metabolized in the liver by cyt P-450 3A4. 10-20 metabolites have been identified; several of these have been found in the whole blood. It is not clear whether the nephrotoxicity of cyclosporine is the result of toxic levels of the parent drug, or of the metabolites, or combination of both.

A number of drugs affect the blood concentration of cyclosporine. Inducers of cyt P-450 3A4, including phenytoin, phenobarbital & rifampin, are reported to increase cyclosporine blood concentrations, presumably through increased metabolism; erythromycin increases blood concentration by inhibiting clearance. The use of cyclosporine is associated with serious toxic side effects, primarily nephrotoxicity & hepatotoxicity. Other adverse effects include diarrhea, gum hyperplasia, nausea, vomiting, hirsutism, tremor & hypertension.

Specimen

• Whole Blood specimens (EDTA) are used in this assay.
• The specimens should be kept at room temperature.

SAMPLE VOLUME: 150 uL of specimen is the minimum volume required.

More general terms

• cyclosporin A in body fluid
• therapeutic drug measurement

More specific terms

• cyclosporin A in blood 1 hour post dose
• cyclosporin A in blood 2 hours post dose
• cyclosporin A in blood 3 hours post dose
• cyclosporin A in blood 4 hours post dose
• cyclosporin A in blood by immunoassay
• cyclosporin A in blood by LC/MS/MS
• cyclosporin A in blood peak
• cyclosporin A in blood trough
• cyclosporin A in dried blood spot

Additional terms

• cyclosporin A (Sandimmune, Neoral [CsA])