Tobramycin-dexamethasone formulation boasts improved surface retention, stability.

In March, Eyevance Pharmaceuticals launched its fixed-dose topical antibiotic and corticosteroid combination to treat steroid-responsive inflammatory ocular conditions. It is intended to be used in cases with a high risk of superficial bacterial ocular infection, or when a potentially dangerous number of bacteria is expected in the eye.¹

Tobradex ST (tobramycin/dexamethasone ophthalmic suspension 0.3%/0.05%) contains XanGen, the company’s proprietary suspension technology that leverages pharmaceutical grade, inactive xanthan gum which is designed to stabilize the combination. The company also states that the agent increases viscosity and retention on the eye, improving the drug’s ocular availability.¹

A NEXT-GENERATION INFECTION FIGHTER

“I am very excited about Eyevance’s launch of Tobradex ST,” says Alice Epitropoulos, MD, clinical associate professor in the department of ophthalmology at The Ohio State University Wexner Medical Center and in private practice at Ophthalmic Surgeons & Consultants of Ohio and the Eye Center of Columbus. “I plan on prescribing it for my patients, providing them the improved, next generation of Tobradex for inflammatory ocular conditions where a risk of bacterial ocular infection exists.

“Tobradex ST utilizes a unique suspension technology formulated with pharmaceutical grade xanthan gum, called XanGen, designed to stabilize the combination and allow greater delivery and ocular surface retention of tobramycin and dexamethasone to the eye,” Dr. Epitropoulos explains. The combination drug is a next generation of the widely used Tobradex product; there is no therapeutic equivalent to the combination.²

The agent’s recommended dosing is the instillation of one drop into the conjunctival sac every 4 to 6 hours. The labeling suggests that during the initial 24 to 48 hours, the dosage may be increased to one drop for every 2 hours.

ADDITIONS, SUBTRACTIONS

Tobradex ST is a change from the original formulation Tobradex, as it has a decreased amount of steroid — from 0.1% to 0.05% — in addition to the added xanthan gum, an inactive agent that allows for increased contact time.² Scoper et al found that the higher viscosity of Tobradex leads to increased retention time and improved bactericidal activity.³

Specifically, the improved pharmacokinetics of Tobradex ST in target ocular tissue revealed concentrations of tobramycin up to 12.5-fold greater compared with original Tobradex.² Investigators also found that dexamethasone concentrations remained similar across the two products. Further, at 10 minutes post-dose, the concentration of tobramycin in the tear film was about eight times higher for the new formulation vs. the original.³

“I feel that this combination will help patients suffering from conditions such as meibomian gland dysfunction, acute blepharitis, conjunctivitis and other inflammatory ocular conditions with risk of infection,” Dr. Epitropoulos says.

CLINICAL DATA

Tobradex ST is associated with rapid relief of symptoms in a randomized, investigator-masked, active-controlled, parallel-group trial conducted at seven private-practice clinical sites in the United States with 122 adult patients who had moderate to severe blepharitis/blepharoconjunctivitis.⁴

After 1 week of dosing with the combination product, patients had significant reduction in symptoms as per a global symptom score determined from the following symptoms, often associated with blepharitis/blepharoconjunctivitis:

• Lid margin redness
• Ocular discharge
• Bulbar conjunctival redness
• Palpebral conjunctival redness
• Lid swelling
• Itchy eyelids
• Gritty eyes

Importantly, no IOP spikes were reported at week 1.⁴ OM

REFERENCES

1. Eyevance Pharmaceuticals. Home ­— TOBRADEX ST (tobramycin/dexamethasone ophthalmic suspension) 0.3%/0.05%. https://mytobradexst.com . Accessed April 14, 2020.
2. US Department of Health and Human Services, Food and Drug Administration. Approved drug products with therapeutic equivalence evaluations. (Orange Book). 38th ed. Washington, DC: US Department of Health and Human Services, Food and Drug Administration; 2018.
3. Scoper SV, Kabat AG, Owen GR, et al. Ocular distribution, bactericidal activity and settling characteristics of TobraDex ST ophthalmic suspension compared with TobraDex ophthalmic suspension. Adv Ther. 2008;25:77-88.
4. Torkildsen GL, Cockrum P, Meier E, et al. Evaluation of clinical efficacy and safety of tobramycin/dexamethasone ophthalmic suspension 0.3%/0.05% compared to azithromycin ophthalmic solution 1% in the treatment of moderate to severe acute blepharitis/blepharoconjunctivitis. Curr Med Res Opin. 2011;27:171-178