The country's first over-the-counter sleeping pills hit shelves Thursday, with their maker forecasting that the drug could meet its original sales target for the year within the first month.

Yet it remains to be seen whether the drug, aimed at countering sleeping disorders, will become a long-term fixture within the medicine cabinets of Japanese households.

SSP Co. said it has received a huge number of drugstore orders for Drewell since its unveiling in mid-March. Shipments of Drewell are expected to amount to 600 million yen by the end of April, when it will be available at 40,000 drugstores.

"Usually in OTC, drugs can be called a hit when more than 500 million yen worth are sold," said Minao Kurita, a spokesman for SSP. "And in that sense, I think Drewell is on track to join these ranks."

Drewell, claimed to be the first sleep-improvement drug to be sold at Japanese pharmacies without a doctor's prescription, features diphenhydramine hydrochloride, a sleep-inducing antihistamine used in common cold medicines.

Six Drewell pills retail for 1,000 yen and 12 for 1,900 yen.

The firm, a subsidiary of German giant Boehringer Ingelheim GmbH, said it hopes to see solid demand from stressed-out workers who suffer from sleep depravation.

Kurita cautioned against an overly optimistic view of sales, however, noting that the initial volume of shipments reflects purchases by stores -- not end users.

"Selling 600 million yen in the first month does not mean that we will see that level of revenue every month," he said.

Indeed, there seemed to be more talking than buying going on at stores on the drug's first day.

Drugstore chain Matsumotokiyoshi Co. said that, as of noon Thursday, it had not sold a single box at its main stores in the Tokyo area, although these stores had received several inquiries.

The sleeping drug, however, has given investors a wake-up call, with SSP shares being snapped up on the strength of the strong orders for Drewell.

SSP shares hit their daily limit within the first hour of Thursday trading, surging 16.55 percent to finish at 704 yen.