To the Editor.
—The editorial by Dr Selzer entitled "Digitalis in Cardiac Failure: Do Benefits Justify Risks?" in the Archives (1981;141-18-20) certainly raises some interesting concepts. However, the section on "Digitalis Dosage" needs clarification insofar as it applies to the use of the Lanoxin brand of digoxin in the United States.No manufacturing variation occurred in Lanoxin tablets manufactured and used in the United States. The Burroughs Wellcome Co in this country has maintained highly consistent manufacturing and formulation techniques on the 200 to 300 lots they produce yearly. Each lot undergoes rigid quality-control procedures, including one-hour dissolution rates that have correlated strongly with in vivo bioavailability determinations.1 Through this approach, Burroughs Wellcome Co produces a digoxin tablet with specifications that are even more rigid than the Food and Drug Administration's requirements. Such Lanoxin brand of digoxin tablets has been the in vivo standard for bioavailability studies in this