Taisho Pharmaceutical Holdings will purchase the French over-the-counter drugmaker UPSA from Bristol-Myers Squibb, the latest move by Japan's top seller of nonprescription medicines to expand overseas.

Taisho said Wednesday it will pay $1.6 billion for UPSA in a transaction scheduled for completion by June next year. 

A household name in Japan, Taisho faces a languishing domestic market for over-the-counter medication. A boost in demand from tourists visiting the country has run its course, adding urgency to its search for overseas growth.

Taisho in 2009 bought Bristol-Myers' Southeast Asian operations, including businesses in Indonesia and the Philippines. The latest purchase is expected to increase Taisho's overseas sales to 25% of the total, from 11% currently.

Founded in 1935, UPSA sells such products as painkillers and suppositories. It generated $480 million in sales, mostly in France, and a $66 million net profit last year. The company was acquired by U.S.-based Bristol-Myers in 1994.

Taisho's core Taisho Pharmaceutical unit has products such as the Lipovitan D energy drink and Pabron cold medicine. Group revenue for the fiscal year ended in March came to 280 billion yen ($2.5 billion).

The $1.6 billion purchase price is roughly six times Taisho's annual net profit and amounts to 24 years' worth of earnings at UPSA.

Taisho held 250 billion yen in cash and securities as of the end of March. The company aims to plow funds into strengthening its overseas business.

Many of the world's leading pharmaceutical groups are unloading their over-the-counter drug operations to focus on higher-value prescription medications.

On Wednesday, U.S.-based Pfizer and the U.K.'s GlaxoSmithKline announced plans to merge their over-the-counter products businesses into a joint venture.

Switzerland-based Novartis sold off its OTC business for $13 billion in March, and Germany's Merck in April sold its consumer health care business to U.S. consumer goods company Procter & Gamble for 3.4 billion euros ($3.89 billion).