U.S. application Ser.  No.  266,843, filed Jul. 5, 1994 (file HX59c) discloses .alpha.-phosphono-sulfonate compounds which are squalene synthetase inhibitors and thereby inhibit cholesterol biosynthesis, and thus are useful as hypocholes-terolemic and antiatherosclerotic agents.  These compounds include those of the following structure ##STR1## wherein R.sup.3 and R.sup.5 are the same or different and are H, alkyl, arylalkyl, aryl, cycloalkyl, a metal ion or other pharmaceutically acceptable cations as defined below, or a prodrug ester;
R.sup.4 is H, alkyl, cycloalkyl, aryl, aryl-alkyl, metal ion or other pharmaceutically acceptable cations as defined below, or a prodrug ester;
Z is H, halogen, lower alkyl or lower alkenyl;
R.sup.1 a lipophilic group containing at least 7 carbons, including pharmaceutically acceptable salts thereof.