Liposome compositions comprising weak acid drugs and uses thereof

A pharmaceutical composition comprising liposomes, the liposomes comprising:

• (a) a lipid bilayer comprising a vesicle-forming lipid, the vesicle-forming lipid comprising a mixture of a first phospholipid and a second phospholipid or a mixture of a first phospholipid and a charged lipid;
• and
• (b) an internal aqueous medium inside the lipid bilayer, the internal aqueous medium comprising a bicarbonate salt and a weak acid drug with a pKa between about 1 to about 6, wherein a molar ratio of the weak acid drug to the bicarbonate salt is from about 0.004:1 to about 1:1;
• wherein the liposomes are suspended in an external medium having a pH above the pKa of the weak acid drug, and
• wherein the encapsulation efficiency of the weak acid drug is at least 50%.