MILWAUKEE (CBS 58/AP) -- The Milwaukee County Medical Examiner's Office (MCMEO) says two powerful drugs are adding to overdose deaths in the county.

There were 604 confirmed overdose deaths in Milwaukee County in 2021. 

Of those deaths, 146 involved para-fluorofentanyl and 21 involved metonitazene. 

The medical examiner says the additional cases are still pending.

Those two drugs are being seen more often in overdose deaths by medical examiners across the U.S.

Of the 604 confirmed OD deaths in Milwaukee County in 2021, 146 involved para-fluorofentanyl and 21 involved metonitazene. Additional cases still pending further toxicology. #fentanylhttps://t.co/mxaIwr7ccM

— Medical Examiner (@mkemedexamine) January 28, 2022

Often they are taken with — or mixed with — illicit fentanyl.

That drug is mainly responsible for the more than 100,000 U.S. deaths reported in the last year.