Disclosed herein is a lipid composition comprising a compound having the formula IA, or a pharmaceutically acceptable salt thereof,whereinR3 is a linear or branched alkylene of 1-6 carbons;R4 and R5 are the same or different, each a hydrogen, or a linear or branched alkyl of 1-6 carbons; andL3 is a bond or an alkane of 1-6 carbons.