The present invention is directed to liposomal compositions comprising a camptothecin, which are optimized to reduce camptothecin degradation and/or precipitation of camptothecin degradation products in the external medium. The invention further provides improved methods of formulating liposomal camptothecins, kits comprising liposome-encapsulated camptothecins, and methods of using the same to treat a variety of diseases and disorders, including cancer.