Netarsudil and latanoprost

Uses

Latanoprost Sterile Ophthalmic Solution is used for the reduction of elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension.

Netarsudil is a rho kinase inhibitor used to reduce intraocular pressure in patients with open angle glaucoma or ocular hypertension.

Netarsudil is indicated for the reduction of elevated intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension .

Netarsudil and latanoprost is also used to associated treatment for these conditions: Increased Intra Ocular Pressure (IOP), Ocular Hypertension, Open Angle Glaucoma (OAG)Increased Intra Ocular Pressure (IOP)

How Netarsudil and latanoprost works

Elevated intraocular pressure leads to an increased risk of glaucomatous visual field loss. The higher the intraocular pressure, the higher the risk of damage to the optic nerve and loss of visual field. Latanoprost selectively stimulates the prostaglandin F2 alpha receptor and this results in a decreased intraocular pressure (IOP) via the increased outflow of aqueous humor, which is often implicated in cases of elevated intraocular pressure. Possible specific mechanisms of the abovementioned increased aqueous outflow are the remodeling of the extracellular matrix and regulation of matrix metalloproteinases. These actions result in higher tissue permeability related to humor outflow pathways, which likely change outflow resistance and/or outflow rates.

The medical condition glaucoma is a leading cause of progressive visual impairment and blindness across the world with primary open-angle glaucoma (POAG) being the major type of glaucoma .

Elevated intraocular pressure (IOP) resulting from increased resistance to aqueous humor outflow is considered a major risk for the development and progression of POAG, but various clinical studies have demonstrated that the reduction and tight control of IOP can delay or prevent POAG and the vision loss associated with it. Ordinary physiological IOP results from aqueous humor produced by the ocular ciliary body and its outflow through two main outflow pathways: the conventional (trabecular) and the unconventional (uveoscleral) pathways .

Under ordinary physiological conditions, diagnostic tracers have shown that the conventional trabecular pathway accounts for up to 90% of aqueous humor outflow. Through this pathway, aqueous humor drains from the anterior chamber sequentially through the uveal and corneoscleral meshwork beams, juxtacanalicular connective tissue (JCT) region, and inner wall (IW) endothelial cells of Schlemm's canal (SC) until finally entering the lumen of SC. From there aqueous humor drains into the collector channels, intravascular plexus, epscleral veins, and finally into the blood circulation .

In glaucomatous eyes, elevated IOP is the result of abnormally increased resistance to aqueous outflow in the conventional trabecular pathway due to apparent increases in the contractile tone and stiffness of the trabecular pathway meshwork (TM), changes in extracellular matrix composition, and/or a decrease in the conductance of the IW endothelial cells of SC .

Subsequently, as a rho kinase inhibitor, the novelty of netarsudil lies in its ability or specificity to apply its mechanism of action directly and specifically at the diseased TM of the conventional trabecular outflow pathway. In particular, rho kinases are serine/threonine kinases that function as important downstream effectors of Rho GTPase. Such activity in the TM and SC drives actomysin contraction, promotes extracellular matrix production, and increases cell stiffness. Acting as an inhibitor of rho kinase, netarsudil consequently reduces cell contraction, decreases the expression of fibrosis-related proteins, and reduces cell stiffness in the TM and SC cells. As a result, netarsudil has been able to demonstrate increases in trabecular outflow facility, increases in the effective filtration area of the TM, cause expansion of the TM tissue, and dilate episcleral veins .

Furthermore, netarsudil is also believed to possess inhibitory action against the norepinephrine transporter (NET). Such inhibition of the NET prevents reuptake of norepinephrine at noradrenergic synapses, which results in an increase in the strength and duration of endogenous norepinephrine signaling. As a consequence of this enhanced signaling, norepinephrine-induced vasoconstriction that can reduce blood flow to the ciliary body may subsequently be responsible for a mechanism in which the formation of aqueous humor may be delayed, prolonged, or reduced as well .

Dosage

Netarsudil and latanoprost dosage

The recommended dosage is 1 drop (1.5 mcg) in the affected eye(s) once daily in the evening. This is for topical ophthalmic use only. Not for injection or oral use.

Side Effects

Eyelash changes (increased length, thickness, pigmentation, and number of lashes); eyelid skin darkening; intraocular inflammation (iritis/uveitis); iris pigmentation changes; and macular edema, including cystoid macular edema. The ocular adverse events and ocular signs and symptoms reported in 5- 15% of the patients on latanoprost in the 6 month, multicenter, double-masked, active-controlled trials were blurred vision, burning and stinging, conjunctival hyperemia, foreign body sensation, itching, increased pigmentation of the iris, and punctate epithelial keratopathy. Local conjunctiva hyperemia was observed; however, less than 1% of the latanoprost treated patients required discontinuation of therapy because of intolerance to conjunctival hyperemia.

Toxicity

The oral LD50 in the rat is > 50 mg/kg.

An overdose of latanoprost is not expected to result in dangerous patient outcomes, however, conjunctival or episcleral hyperemia may occur.An intravenous infusion of 3 μg/kg of latanoprost in healthy volunteers led to mean plasma concentrations of 200 times higher than a normally administered therapeutic dose and no adverse effects were noted. One study suggested that an overdose of latanoprost lead to cystoid macular edema after a large, unintended overdose. This resolved within 4 weeks after 4 weeks following treatment with nepafenac 0.3% eye drops in addition to oral acetazolamide. Contact the local poison control center for updated guidance on the management of a latanoprost overdose.

The most common adverse reaction associated with netarsudil dosed once daily in controlled clinical studies was conjunctival hyperemia which was reported by 53% of patients. Other common adverse affects reported (about 20%) include corneal verticillata, instillation site pain, and even conjunctival hemorrhage. Still other reactions include instillation site erythema, corneal staining, blurred vision, increased lacrimiation, erythema of eyelid, and reduced visual acuity being reported by 5-10% of patients in clinical studies .

When using multiple dose containers of topical ophthalmic products there is a possibilty of contaminating the containers with agents that may cause bacterial keratitis by patients who in many cases have a concurrent corneal disease or a disruption of the ocular epithelial surface .

Although systemic exposure to netarsudil from ocular administration is low, there is no formal available data on the safe use of netarsudil in pregnant women .

There is no formal data available on whether significant netarsudil levels could be present in human milk following ocular administration, on the effects on the breastfed enfant, or on the effects on milk production .

The safety and effectiveness of using netarsudil in pediatric patients below the age of 18 years have not been established .

No overall differences in safety or effectiveness have been observed between elderly and other aduly patients .

Long-term studies in animals have not been performed to evaluate the carcinogenic potential of netarsudil. Netarsudil was not mutagenic in the Ames test, in the mouse lymphoma test, or in the in vivo rat micronucleus test. Studies to evaluate the effects of netarsudil on male or female fertility in animals have not been performed .

Precaution

Ophthalmic Solution may gradually increase the pigmentation of the iris. The eye color change is due to increased melanin content in the stromal melanocytes of the iris rather than to an increase in the number of melanocytes. During clinical trials, the increase in brown iris pigment has not been shown to progress further upon discontinuation of treatment, but the resultant color change may be permanent. Eyelid skin darkening, which may be reversible. There may be increased length, thickness, pigmentation, the number of lashes or hairs, and misdirected growth of eyelashes. Eyelash changes are usually reversible upon discontinuation of treatment. It should be used with caution in patients with a history of intraocular inflammation (iritis/uveitis) and should generally not be used in patients with active intraocular inflammation. This drug should be used with caution in patients who do not have an intact posterior capsule or who have known risk factors for macular edema.

Interaction

In vitro studies have shown that precipitation occurs when eye drops containing thimerosal are mixed with latanoprost. If such drugs are used they should be administered with an interval of at least 5 minutes between applications.

Volume of Distribution

The volume of distribution of latanoprost is 0.16 ± 0.02 L/kg. The activated acid form of latanoprost can be measured in aqueous humor in the initial 4 hours post-administration, and it is measured in the plasma only for 1 hour following ophthalmic administration. This drug is more lipophilic than its parent prostaglandin and easily penetrates the cornea. It has been shown to cross the placenta in rats.

As netarsudil and its active metabolite demonstrate a high degree of protein binding , it is expected to exhibit a low volume of distribution.

Elimination Route

This drug is rapidly absorbed in the cornea as an isopropyl ester prodrug and is then activated by the process of hydrolysis. A small amount of this drug is systemically absorbed. The Cmax of latanoprost in the systemic circulation is reached after 5 minutes and is measured to be 53 pg/mL. The Cmax in the aqueous humor is attained within 2 hours after administration. and has been estimated to be 15-30 ng/mL.

The systemic exposure of netarsudil and its active metabolite, AR-13503, after topical ocular administration of netarsudil opthalmic solution 0.02% once daily (one drop bilaterally in the morning) for eight days in 18 healthy subjects demonstrated no quantifiable plasma concentrations of netarsudil (lower limit of quantitation [LLOQ] 0.100 ng/mL) post dose on Day 1 and Day 8. Only one plasma concentration at 0.11 ng/mL for the active metabolite was observed for one subject on Day 8 at 8 hours post dose .

Half Life

The elimination half-life of latanoprost from the plasma is about 17 minutes. The elimination half-life of latanoprost from the eye is estimated at 2–3 hours.

The half-life of netarsudil incubated in vitro with human corneal tissue is 175 minutes .

Clearance

The systemic clearance of latanoprost is 7 mL/min/kg.

The clearance of netarsudil is strongly influenced by its low plasma concetrations following topical administration and absorption and high protein binding in human plasma inn .

Elimination Route

After hepatic beta-oxidation, the metabolites of latanoprost are primarily found to be excreted by the kidneys. About 88% of the latanoprost dose is recovered in the urine after topical administration. About 15% of a dose is reported to be excreted in the feces.

Clinical studies assessing the in vitro metabolism of netarsudil using corneal tissue from humans, human plasma, and human liver microsomes and microsomal S9 fractions demonstrated that netarsudil metabolism occurs through esterase activity. Subsequent metabolism of netarsudil's esterase metabolite, AR-13503, was not detectable. In fact, esterase metabolism in human plasma was not detected during a 3 hour incubation .

Pregnancy & Breastfeeding use

Pregnancy Category C. There are no adequate and well controlled studies in pregnant women. The drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Contraindication

Known hypersensitivity to latanoprost, benzalkonium chloride or any other ingredients in this product.

Special Warning

Pediatric Use: Safety and effectiveness in pediatric patients have not been established.

Geriatric Use: No overall differences in safety or effectiveness have been observed between elderly and younger patients.

Storage Condition

Before opening the cap, keep the bottle in its box in a refrigerator (2°-8° C) protected from light. After opening, keep the bottle in its box in a cool place below 25° C. The contents should be used within one month after the dropper is opened. Keep out of reach of children

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