A stable-labeled internal standard of cyclosporin A, an immunosuppressant and narrow therapeutic index drug used to prevent rejection in organ transplantation. This internal standard is suitable for critical quantitative applications in clinical and diagnostic testing such as therapeutic drug monitoring assays to ensure patients remain within the drug’s narrow therapeutic range. The Snap-N-Spike® format allows laboratories to eliminate weighing operations of hazardous substances such as cyclosporin A, significantly reducing occupational exposure hazards related to handling of acutely toxic powders and provides the ability to spike into their matrix of choice before use.