Dextenza

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Overview

       Limits in patients physical dexterity, error in drug administration, contamination of dispenser, and complex dosing regimens are barriers to administration of topical eye drops. [1-3] Moreover, improper tapering of steroids can lead to rebound ocular inflammation. [4] Dexamethasone ophthalmic insert (Dextenza, Ocular Therapeutix, Inc) is an intracanalicular insert that uses a biodegradable polyethylene glycol hydrogel to deliver sustained and tapered release of dexamethasone over 30 days for ophthalmic post-operative pain and inflammation. [3,5] This novel drug delivery may circumvent compliance concerns, alleviate burden on patients, and provide optimal surgical outcomes. 

Indications

Dextenza is FDA approved for the treatment of ocular inflammation and pain following ophthalmic surgery. [5] This may be a good option for patients with physical or mental limitations that make drops challenging, patients at higher risk for inflammation such as uveitis, patients with severe dry eyes as the dexamethasone ophthalmic insert acts as a punctal plug for better lubrication, or a patient that wants the convenience of drop-less post-operative management. [3,5,7]

Contraindications

Dexamethasone ophthalmic insert is contraindicated in patients with an active infection in the corneal, conjunctiva, or canaliculus; fungal infection of the eye; and dacryocystitis. [5]

Clinical Pharmacology

       Dexamethasone is a potent corticosteroid that inhibits proinflammatory cytokines such as interleukin-1, tumor necrosis factor, interferon-gamma, and granulocyte-macrophage colony-stimulating factor. Ultimately, dexamethasone causes decreased migration of neutrophils, permeability of capillary membranes, and edema. [6]

A prospective multicenter randomized double-masked phase 3 study found that following cataract surgery, patients with dexamethasone insert, compared to placebo, had an absence of ocular pain (79.6% versus 61.3%; P < 0.0001) at day 8 and less anterior chamber cells (52.3% versus 31.1%; P < 0.0001) at day 14. Twice as many patients in the placebo group required rescue therapy at day 14. [7]

       Plasma levels of dexamethasone were measured in healthy volunteers before and after insertion of dexamethasone ophthalmic insert on days 1, 4, 8, 15, 22, and 29. The lower limit of detectable levels was 0.05 ng/mL and was found in 11% of samples ranging from 0.05 ng/mL to 0.81 ng/mL. [5] 

Adverse Reactions

       Ocular side effects of corticosteroids include rebound inflammation, increased intraocular pressure, steroid-induced glaucoma, cataract formation, delayed wound healing, and increased risk of infection. [5,8] 

Patient Experience

       In a cross-sectional, qualitative study that recruited twenty-five patients, 92% of patients reported the highest level of satisfaction for various reasons: absence of pain, ease of use compared to eye drops, comfort, and improvement in compliance. One patient reported dissatisfaction due to increased healing time and epiphora. All patients rated the insert as comfortable with 84% reporting unawareness of the insert. 84% of participants reported a willingness to pay more for the insert compared to eye drops. [3]

Dosage and Administration

      A single cylindrical insert is approximately 0.5 mm in diameter and 3 mm in length, containing 0.4 mg of dexamethasone that is released in a tapered manner over the course of 30 days. [5] 
      To administer, temporal traction is applied to the eyelid to open the angle of the canaliculus. Then, an ophthalmic dilator is used to dilate the punctum while avoiding perforation of the canaliculus. The punctal area is thoroughly dried before insertion as the hydrogel quickly swells upon contact with moisture. If the dexamethasone ophthalmic insert hydrates before fully inserted, a new insert should be used. The drug is advanced with blunt forceps until the distal end is slightly below the punctal opening. Swelling of the hydrogel ensures retention in the canaliculus. The hydrogel is conjugated with fluorescein so it can be visualized with a blue light with a yellow filter to confirm proper placement. [4,5]  

Dexamethasone ophthalmic insert remains in the vertical canaliculus for approximately thirty days. After treatment, subsequent removal by the surgeon is not necessary because the insert is liquified by hydrolysis and is cleared through the nasolacrimal duct.3 However, if necessary, the insert can be removed with saline irrigation or manual expression. [5]

Patient’s Instructions for Use

      Advise patients to contact their surgeon if pain, swelling, photophobia, ocular discharge, or redness occurs. [5,8]  

https://www.dextenza.com/wp-content/uploads/DEX_PatientAssistanceProgramApplicationForm.pdf

References

1. R K, Rj C, Yp J, Ym B. Multicenter Study of Compliance and Drop Administration in Glaucoma. Canadian journal of ophthalmology Journal canadien d'ophtalmologie. 2008. 2. Claxton AJ, Cramer J, Pierce C. A systematic review of the associations between dose regimens and medication compliance. Clin Ther. 2001;23(8):1296-1310. 3. Gira JP, Sampson R, Silverstein SM, Walters TR, Metzinger JL, Talamo JH. Evaluating the patient experience after implantation of a 0.4 mg sustained release dexamethasone intracanalicular insert (Dextenza™): results of a qualitative survey. Patient Prefer Adherence. 2017;11:487-494. 4. Blizzard C, Desai A, Driscoll A. Pharmacokinetic Studies of Sustained-Release Depot of Dexamethasone in Beagle Dogs. J Ocul Pharmacol Ther. 2016;32(9):595-600. 5. DEXTENZA [package insert]. Bedford, MA: Ocular Therapeutix Inc; 2019 6. Johnson DB, Kelley B. Dexamethasone. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2020. 7. Tyson SL, Bafna S, Gira JP, et al. Multicenter randomized phase 3 study of a sustained-release intracanalicular dexamethasone insert for treatment of ocular inflammation and pain after cataract surgery. J Cataract Refract Surg. 2019;45(2):204-212. 8. Renfro L, Snow JS. Ocular effects of topical and systemic steroids. Dermatol Clin. 1992;10(3):505-512.