Patent ID: 8034376

Claim:
An association complex comprising: a. one or more compounds, each individually having a structure defined by formula (I) or a pharmaceutically acceptable salt thereof wherein: each X a and X b , for each occurrence, is independently C 1-6 alkylene; n is 0, 1, 2, 3, 4, or 5; each R is independently H or wherein: at least n+2 of the R moieties in at least about 80% of the molecules of the compound of formula (I) in the preparation are not H; m is 1, 2, 3 or 4; Y is O, NR 2 , or S; R 1 is alkyl or alkenyl; each of which is optionally substituted with one or more substituents; and R 2 is H, alkyl or alkenyl; each of which is optionally substituted each of which is optionally substituted with one or more substituents; provided that, if n=0, then at least n+3 of the R moieties are not H; b. PEG-lipid having the structure shown in formula (XV) wherein: each L 1 and L 2 are independently a bond or C(O); each R 1 and R 2 are independently alkyl alkenyl or alkynyl; each of which is optionally substituted with one or more substituents; X is —C(O)NH—, C(S)NH, —C(O)C 1-3 alkylC(O)NH—; or —C(O)C 1-3 alkyl-C(O)O—; m is an integer from 0-11 and n is an integer from 1-500; c. a steroid; and d. a nucleic acid.