A pharmaceutical composition comprising discrete composite particles comprising: at least one 20-camptothecin derivative; at least one surfactant, which is a poloxamer; at least one stabilizer, which is at least one of a cellulose and a cellulose derivative selected from the group consisting of methylcellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, sodium carboxymethyl cellulose, cellulose acetate, cellulose actetate butyrate, cellulose phthalate, cellulose acetate phthalate, hydroxypropylmethylcellulose phthalate, or any combinations thereof; and at least one diluent, which is mannitol, xylitol, lactitol, sorbitol, maltitol, cellobitol, erythritol, isomalt, lactose, potato starch, corn starch, glucose, sucrose, dextran, or any combinations thereof; wherein at least 50 vol.% of the particles have a particle size of 2500 nm or less, the particle size referring to the actual diameter of the particles where they are spherical or an equivalent diameter when they are non-spherical; wherein the active pharmaceutical ingredient, the surfactant, the stabilizer, and the diluent each are in solid form; and wherein the 20-camptothecin derivative is at least one camptothecin ester having the formula: wherein R represents H, NO 2, NH 2, N 3, -OH, a halogen, carboxyl, a C 1-16 alkyl group, C 2-16 alkenyl group, a C 3-8 cycloalkyl group, a C 1-8 alkoxyl group, an aroxyl group, CN, SO 3 H, a C 1-8 halogenated alkyl group, (CH 2) n NR 2 7 where R 7 can be H or a C 1-8 alkyl group and n can be an integer of from 1 to 8, hydroxyl, SH, SR 8 where R 8 can be a C 1-8 alkyl group or an unsubstituted phenyl group or a substituted phenyl group, a carbonyl group COR 9 where R 9 can be a C 1-8 alkyl group or an unsubstituted phenyl group or a substituted phenyl group, or a SiR 3 10 where R 10 can be a C 1-4 alkyl group, and R 2 can be an alkyl group, a cycloalkyl group, an alkenyl group, or an epoxy group. at least one 20-camptothecin derivative; at least one surfactant, which is a poloxamer; at least one stabilizer, which is at least one of a cellulose and a cellulose derivative selected from the group consisting of methylcellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, sodium carboxymethyl cellulose, cellulose acetate, cellulose actetate butyrate, cellulose phthalate, cellulose acetate phthalate, hydroxypropylmethylcellulose phthalate, or any combinations thereof; and at least one diluent, which is mannitol, xylitol, lactitol, sorbitol, maltitol, cellobitol, erythritol, isomalt, lactose, potato starch, corn starch, glucose, sucrose, dextran, or any combinations thereof; wherein at least 50 vol.% of the particles have a particle size of 2500 nm or less, the particle size referring to the actual diameter of the particles where they are spherical or an equivalent diameter when they are non-spherical; wherein the active pharmaceutical ingredient, the surfactant, the stabilizer, and the diluent each are in solid form; and wherein the 20-camptothecin derivative is at least one camptothecin ester having the formula: wherein R represents H, NO 2, NH 2, N 3, -OH, a halogen, carboxyl, a C 1-16 alkyl group, C 2-16 alkenyl group, a C 3-8 cycloalkyl group, a C 1-8 alkoxyl group, an aroxyl group, CN, SO 3 H, a C 1-8 halogenated alkyl group, (CH 2) n NR 2 7 where R 7 can be H or a C 1-8 alkyl group and n can be an integer of from 1 to 8, hydroxyl, SH, SR 8 where R 8 can be a C 1-8 alkyl group or an unsubstituted phenyl group or a substituted phenyl group, a carbonyl group COR 9 where R 9 can be a C 1-8 alkyl group or an unsubstituted phenyl group or a substituted phenyl group, or a SiR 3 10 where R 10 can be a C 1-4 alkyl group, and R 2 can be an alkyl group, a cycloalkyl group, an alkenyl group, or an epoxy group.