Latanoprostene bunod

Open-angle glaucoma (OAG) is a medical condition that is associated with progressive visual field damage and the loss of vision.

Occular hypertension (OHT) is considered a key risk factor for OAG and reducing intraocular pressure (IOP) and being able to maintain unique and appropriate target IOPs for various different patients having OHT can delay or prevent the onset of primary OAG or slow the disease progression of established glaucoma.

Ordinary physiological IOP results from aqueous humor produced by the ocular ciliary body and its outflow through a) the trabecular meshwork (TM) and Schlemm's canal (SC) in what is called the conventional pathway, and b) the uveoscleral pathway via the ciliary muscle/choroid/sclera in what is refered to as the unconventional pathway.

In patients with OHT or OAG there is increased resistance to aqueous humor outflow by way of the TM/SC pathway, which causes increased IOP. This increase in IOP is believed to be the cause of mechanical stress on the posterior structures of the eye which can result in the dysfunction of optic nerve fibers and the destruction of retinal ganglion cells - all of which ultimately contributes to vision loss.

As there is no cure for glaucoma, therapeutic management is predominantly focused on minimizing disease progression and clinical sequelae via the reduction and maintainenance of appropriate target IOPs.

Subsequently, latanoprostene bunod is thought to lower intraocular pressure via a dual mechanism of action since the medication is metabolized into two relevant moieties upon administration: (1) latanoprost acid, and (2) butanediol mononitrate.

As a prostaglandin F2-alpha analog, the latanoprost acid moiety operates as a selective PGF2-alpha (FP) receptor agonist. Since FP receptors occur in the ciliary muscle, ciliary epithelium, and sclera the latanoprost acid moiety primarily acts in the uveoscleral pathway where it increases the expression of matrix metalloproteinases (MMPs) like MMP-1, -3, and -9 which promote the degradation of collagen types I, III, and IV in the longitudinal bundles of the ciliary musicle and surrounding sclera. The resultant extracellular matrix remodeling of the ciliary muscle consequently produces reduced outflow resistance via increased permeability and increased aqueous humor outflow through the uveoscleral route.

Conversely, the butanediol mononitrate undergoes further metabolism to NO and an inactive 1,4-butanediol moiety. As a gas that can freely diffuse across plasma membranes, it is proposed that the relaxing effect of NO to induce reductions in the cell volume and contractility of vascular smooth muscle like cells is dependant upon activation of the sGC/cGMP/PKG cascade pathway. NO released from butanediol mononitrate consequently enters the cells of the TM and inner wall of SC, causing decreases in myosin light chain-2 phosphorylation, increased phosphorylation of large-conductance calcium-activated potassium (BKCa) channels, and a subsequent efflux of potassium ions through such BKCa channels. All of these changes serve to decrease the cell contractility and volume, as well as to rearrange the actin cytoskeleton of the TM and SC cells. These biomechanical changes ultimately allow for enhanced conventional outflow of aqueous humor.