Panache was established by McKillen and James Dale, another Kiwi founding shareholder of 42 Below, in 2004.
It operated as the exclusive US importer of the New Zealand vodka brand until its sale to Bacardi.
McKillen's involvement with Panache ended after 42 Below was sold and he no longer holds shares in the firm, which is listed on New York's OTC Markets exchange, an alternative trading system.
Panache is involved in the development, sales and marketing ofspirits.
Its three brands are Wodka Vodka, Alchemia Infused Vodka and Alibi American Whiskey.
McKillen said that after the acquisition, which would require approval from New Zealand's Overseas Investment Office, Panache and VnC would benefit from combined distribution channels and "synergies in manufacturing".
Last year McKillen said he had exploited his distribution networks from his days with 42 Below to establish VnC in 30 markets around the globe.
VnC exported 120,000 cases of product in the 12 months to March 2011, valued at about $10 million.