In a statement the 38-year-old said: “I have had independent doctors test me, both blood and urine and all of my results show that I am completely clean. I have never taken performance-enhancing drugs, and I never will.”
Caparello said he requested drug testing to be included in the contract negotiations for the Nyika fight.
Testing is not mandatory, as Nyika is not ranked in the top 15 of the World Boxing Council (WBC).
“I was not in the WBC top 15, nor was I defending a WBC belt so I had little obligation to take an out of contest VADA test however I had nothing to hide so I took the voluntary test.
“I intend to challenge VADA on all of these findings. Independent, highly qualified doctors have already gone on record stating that all my test results are within the required levels.”
Caparello said these allegations are deeply embarrassing for him, his team and his family.
“I have always honoured the rules of my sport. I will be contesting these findings and am very confident that my name will be cleared.”
Duco Events promoters David Higgins and Joseph Parker will announce a late replacement for Nyika on Thursday, with the event proceeding as planned.
“Higgins and Parker have secured a tough, credible and vastly experienced opponent who wants to take on Nyika at short notice,” Duco said.