Pharmstandard said it has finalized terms to buy the Singapore-based pharmaceutical ingredient supplier Bever Pharmaceutical for $590 million.

For Russia’s Pharmstandard, the deal secures a long-term fixed-cost source of pharmaceutical ingredients for two of its flagship, over-the counter brands, an anti-viral drug and an anti-anxiety drug. The deal is also expected to improve the profitability of the company’s over-the-counter business, which Pharmstandard has proposed to spin off as a separate company.

The deal, which must still be approved by Pharmstandard shareholders, will be financed by a combination of $542 million in stock and $48 million in cash. The money goes to Alexander Shuster, a Russian national that controls Bristley Enterprises, which owns 100 percent of Bever. After the deal is completed, Shuster will become the Russian drugmaker’s second largest shareholder, owning about 18.7 percent of the company. He is also a non-executive member of Pharmstandard’s board of directors.

Russia’s pharmaceutical industry is dominated by foreign companies. Pharmstandard is Russia’s biggest domestic pharmaceutical company with a market capitalization of about $2 billion.

The deal was originally valued at $630 million when first announced in July, but worries about the deal and its rationale triggered a sell-off of Pharmstandard shares, which are currently trading about 25 percent below their price before the deal was announced.