TRENTON, N.J. (AP) — As Hurricane Sandy barreled into the East Coast on Monday, drugmakers from Washington, D.C., to Massachusetts closed nearly all their facilities, although emergency personnel were at key sites.

None of the companies reported disruptions in the supply of medicines that might affect patients or hospitals, but the closures included numerous medicine factories and distribution centers. Several companies were extending the shutdown through Tuesday.

Express Scripts Holding Co., the huge prescription-benefit manager, said that it waived its restriction on "refill too soon" notices to help people in areas affected by the hurricane who lost their prescription medications. Its New Jersey office building and a mail-order pharmacy in Willingboro were open.

All of Johnson & Johnson's offices and factories in New Jersey and Pennsylvania were closed, as were most GlaxoSmithKline PLC facilities in the Northeast, Novo Nordisk A/S offices in Princeton, N.J., and Roche Group's Nutley, N.J., campus.

Merck & Co. Inc.'s New Jersey offices and a factory were running with limited personnel. But like virtually every company contacted by The Associated Press, most of Merck's staff was working from their homes.

Companies that closed their U.S. or world headquarters, research labs and sales offices in New York, New Jersey, Delaware and eastern Pennsylvania on Monday also included Pfizer Inc., Bristol Myers-Squibb Co., AstraZeneca PLC, Sanofi SA, GlaxoSmithKline PLC, Watson Pharmaceuticals Inc., Teva Pharmaceuticals, Daiichi Sankyo, and Novartis AG. Bayer HealthCare sent workers home at midday.

Medicine factories were closed by AstraZeneca, Daiichi Sankyo, Teva and Novartis, as well as J&J and Glaxo. Some companies said closed factories might reopen for the overnight shift.

In the Boston area, medical-device maker Boston Scientific Inc. closed two offices, a factory and a distribution center.