The Food and Drug Administration (FDA) is revoking the temporary exemption that has allowed single-entity coronary vasodilator drug products containing erythrityl tetranitrate to remain on the market beyond the time limits scheduled for implementation of the Drug Efficacy Study. FDA is announcing that the products lack substantial evidence of effectiveness and is offering an opportunity for a hearing on a proposal to withdraw approval of any applicable new drug applications (NDA's) or abbreviated new drug applications (ANDA's).