March 31 (Bloomberg) -- Caraco Pharmaceutical Laboratories Ltd. recalled generic heart tablets that may contain the wrong amount of medicine, sending the drugmaker down the most in four months in New York trading.

The voluntary recall covers 0.125 milligram and 0.25 milligram digoxin tablets distributed before today and within the expiration date of September 2011, according to statements released today by the company and the U.S. Food and Drug Administration. Size differences among the pills may mean they have too much or too little of the active ingredient.

Caraco’s voluntary recall follows a similar move by Actavis Group hf almost a year ago over concerns that some of its generic digoxin tablets may be twice as thick as intended. The medicine has a narrow margin between recommended and lethal doses, and errors in pill size may lead to heart instability, serious side effects or death, especially in patients with kidney failure.

The company and the FDA didn’t say whether anyone has been harmed by the Caraco products. The agency said last year that it received “several reports of illnesses and injuries” tied to the Actavis pills, distributed by Mylan Inc.

Detroit-based Caraco fell $1.03 cents, or 23 percent, to $3.52 at 4 p.m. in New York Stock Exchange composite trading. The drop was the biggest single-day decline since Dec. 1. The company is majority owned by Sun Pharmaceutical Industries Ltd., of Mumbai.

Digoxin is sold by several makers of generic drugs to treat heart failure and abnormal heart rhythms. It is a form of digitalis, a chemical derived from foxglove plants that has been used in cardiology since the 18th century.

To contact the reporter on this story: Catherine Larkin in Washington at clarkin4@bloomberg.net.

Last Updated: March 31, 2009 16:09 EDT