Jeetendra Harish Belani, 37, of Nagpur made the admission in the Pittsburgh federal court before Chief Federal District Judge Mark Hornak on Monday, federal prosecutor Scott Brady said.
Belani admitted that to evade detection he falsified customs declarations for the medicines that can only be sold with a doctor's prescription and had them sent to different addresses in small quantities, the prosecutor said.
He was arrested in the Czech Republic in early June and extradited to the US where he was charged later that month with drug and money laundering offences, according to officials.
According to Brady, Belani admitted that the drugs were imported to the US through his India-based company, LeeHPL Ventures, between 2015 and 2019 and maintained a website for it.
The medicines smuggled included Tapentadol, a Schedule II drug, as well as Tramadol, Carisoprodol, and Modafinil, which are Schedule IV controlled substances, officials said.
According to the Drug Enforcement Agency, Schedule II drugs "have a high potential for abuse which may lead to severe psychological or physical dependence" while Schedule IV drugs "have a low potential for abuse relative to substances".
Belani also admitted that he conspired with two others, William Kulakevich and Julia Fees, between 2015 and mid-2017 to smuggle a drug known as Etizolam for re-sale by the two through a website, Brady said.
Etizolam is "part of a class of drugs similar to benzodiazepines, which are often used to treat insomnia and anxiety and carry a potential for abuse and overdose," according to officials.
Belani also admitted to having money sent to his accounts in India and other countries leading to the money laundering charge, Brady said.
Persons facing charges admitting their guilt in court is known as pleading guilty and is often done in return for leniency as prosecutors can avoid a costly court case.
(Arul Louis can be contacted at arul.l@.in and followed on Twitter @arulouis)
( With inputs from IANS )