Determination of an echinocandin, MK-0991, in mammalian plasma by radioimmunoassay

J Pharm Biomed Anal. 2001 Jul;25(5-6):811-20. doi: 10.1016/s0731-7085(01)00344-2.


A quantitative method based on radioimmunoassay for the determination of the antifungal agent, CANCIDAS (MK-0991) has been developed and validated. The immunogen was prepared by coupling MK-0991 to bovine serum albumin through a two-step reaction with difluorodinitrobenzene. An antiserum specific to MK-0991 was selected for RIA. The assay was based on the competitive immunoassay principle in which the drug competes with iodinated drug for a limited quantity of specific antibody. The bound tracer was separated via goat anti-rabbit globulin. The assay demonstrates good accuracy and reproducibility at plasma concentration down to 10 ng/ml. The specificity of the RIA method was confirmed by cross-validating against an established HPLC method.

MeSH terms

  • Animals
  • Anti-Bacterial Agents / blood*
  • Anti-Bacterial Agents / metabolism
  • Caspofungin
  • Echinocandins
  • Lipopeptides
  • Peptides*
  • Peptides, Cyclic*
  • Rabbits
  • Radioimmunoassay / methods*
  • Radioligand Assay
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Serum Albumin, Bovine / metabolism


  • Anti-Bacterial Agents
  • Echinocandins
  • Lipopeptides
  • Peptides
  • Peptides, Cyclic
  • Serum Albumin, Bovine
  • Caspofungin