CONCURRENTLY USED WITH IMMUNOSUPPRESSANTS (CYCLOSPORIN), FIBRIC ACID DERIVATIVES OR NICOTINIC ACID, THERE IS AN INCREASED RISK OF MYOPATHY & RENAL FAILURE. BLEEDING AND PROTHROMBIN TIME HAVE BEEN INCREASED WHEN LOVASTATIN USED WITH COUMARIN ANTICOAGULANTS. MIBEFRADIL RAISED CONCENTRATIONS OF LOVASTATIN. CONCURRENT ADMINISTRATION OF DIGOXIN MAY CAUSE A SLIGHT ELEVATION IN SERUM DIGOXIN CONCENTRATION. CONCURRENT USE OF CHOLESTYRAMINE OR COLESTRIPOL MAY DECREASE THE BIOAVAILABILITY OF SIMVASTATIN.