A compound according to formula: or a pharmaceutically acceptable salt thereof, wherein: Y is selected from the group consisting of alkylene, aryl, heteroaryl, cycloalkyl, and heterocyclyl, any of which may be optionally substituted; B is selected from the group consisting of -NR 1 R 2, -CH 2 NR 1 R 2, -CH(R 10)R 2, -CCH 3 (R 10) R 2, -NHCH(R 10)R 2, -N(CH 3)R 2, -CH 2 CH 2 R 2, -CH(R 10)CH 2 R 2, and -CH 2 CH(R 10)R 2; R 1, R 2 and R 10 are each independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, amino, aryl, heteroaryl, cycloalkyl and heterocycloalkyl, any of which may be optionally substituted; X 1 and X 2 are independently selected from the group consisting of hydrogen, hydroxy, halogen, alkyl, amino, nitro, cyano, carbonyl, carbonylamino, alkoxy, aryloxy, sulfonyl, sulfonamido, thioalkyl, and carboxyl; and PG is an acyl radical of a prostaglandin selected from latanoprost, bimatoprost, travoprost, tafluprost, AR-102, cloprostenol, 13,14-dihydrocloprostenol, unoprostone, PGF 1α, PGF 2α, and PGF 3α, or an acyl radical of formula: or an optical isomer, diastereomer, or enantiomer thereof, wherein: the dashed lines independently indicate the presence or absence of a bond; A and B are independently -(CR a R b) n -, wherein each R a and R b is independently hydrogen or C 1 -C 6 alkyl, and n is 0, 1, 2, 3, or 4; R 1 is -C -; R 2 is hydrogen or C 1 -C 6 alkyl; R 3, R 4 and R 5 are independently hydrogen or an alcohol protecting group; Y is a bond, -O-, -S-, -S, -SO 2 -, -C(R g) 2 -, -CR h =CR i -, -NR j -, or - C=C-; Z is hydrogen, cycloalkyl, heterocyclyl, aryl, or heteroaryl; R g, R h and R i are independently hydrogen, C 1 -C 6 alkyl, alkoxy, or hydroxy; and R j is hydrogen or C 1 -C 6 alkyl. Y is selected from the group consisting of alkylene, aryl, heteroaryl, cycloalkyl, and heterocyclyl, any of which may be optionally substituted; B is selected from the group consisting of -NR 1 R 2, -CH 2 NR 1 R 2, -CH(R 10)R 2, -CCH 3 (R 10) R 2, -NHCH(R 10)R 2, -N(CH 3)R 2, -CH 2 CH 2 R 2, -CH(R 10)CH 2 R 2, and -CH 2 CH(R 10)R 2; R 1, R 2 and R 10 are each independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, amino, aryl, heteroaryl, cycloalkyl and heterocycloalkyl, any of which may be optionally substituted; X 1 and X 2 are independently selected from the group consisting of hydrogen, hydroxy, halogen, alkyl, amino, nitro, cyano, carbonyl, carbonylamino, alkoxy, aryloxy, sulfonyl, sulfonamido, thioalkyl, and carboxyl; and PG is an acyl radical of a prostaglandin selected from latanoprost, bimatoprost, travoprost, tafluprost, AR-102, cloprostenol, 13,14-dihydrocloprostenol, unoprostone, PGF 1α, PGF 2α, and PGF 3α, or an acyl radical of formula: or an optical isomer, diastereomer, or enantiomer thereof, wherein: the dashed lines independently indicate the presence or absence of a bond; A and B are independently -(CR a R b) n -, wherein each R a and R b is independently hydrogen or C 1 -C 6 alkyl, and n is 0, 1, 2, 3, or 4; R 1 is -C -; R 2 is hydrogen or C 1 -C 6 alkyl; R 3, R 4 and R 5 are independently hydrogen or an alcohol protecting group; Y is a bond, -O-, -S-, -S, -SO 2 -, -C(R g) 2 -, -CR h =CR i -, -NR j -, or - C=C-; Z is hydrogen, cycloalkyl, heterocyclyl, aryl, or heteroaryl; R g, R h and R i are independently hydrogen, C 1 -C 6 alkyl, alkoxy, or hydroxy; and R j is hydrogen or C 1 -C 6 alkyl. the dashed lines independently indicate the presence or absence of a bond; A and B are independently -(CR a R b) n -, wherein each R a and R b is independently hydrogen or C 1 -C 6 alkyl, and n is 0, 1, 2, 3, or 4; R 1 is -C -; R 2 is hydrogen or C 1 -C 6 alkyl; R 3, R 4 and R 5 are independently hydrogen or an alcohol protecting group; Y is a bond, -O-, -S-, -S, -SO 2 -, -C(R g) 2 -, -CR h =CR i -, -NR j -, or - C=C-; Z is hydrogen, cycloalkyl, heterocyclyl, aryl, or heteroaryl; R g, R h and R i are independently hydrogen, C 1 -C 6 alkyl, alkoxy, or hydroxy; and R j is hydrogen or C 1 -C 6 alkyl.