Novel derivatives of prostaglandin compounds of the F-series (PGF), specifically macrocyclic internal 1,15-lactones of fluprostenol and related PGF analogs, such as cloprostenol or latanoprost. The novel analogs can be formulated into ophthalmic solutions and topically applied for the treatment of the increased intraocular pressure caused by glaucoma and the reduction of ocular hypertension.