Pfizer Inc shares drop by 8.3%

Pfizer Inc shares slumped by as much as 8.3% after a doctor said in an article in the New England Journal of Medicine that drugmakers must prove that medications such as Pfizer’s Celebrex don’t carry the same risk of heart problems as Merck & Co’s Vioxx.

Pfizer, the world’s largest drugmaker, lost $2.18, or 7%, to $29 as of 10.19am New York time. The shares earlier dropped as low as $28.60. Merck shed $1.32 to $30.35.