Usage
Dexamethasone intravitreal implant is a corticosteroid indicated for the treatment of macular edema following branch retinal vein occlusion (BRVO) or central retinal vein occlusion (CRVO), non-infectious uveitis affecting the posterior segment of the eye, and diabetic macular edema in patients who are pseudophakic or who are phakic and scheduled for cataract surgery. It belongs to the pharmacological class of corticosteroids, specifically glucocorticoids. The mechanism of action involves suppressing inflammation by inhibiting multiple inflammatory cytokines, resulting in decreased edema, fibrin deposition, capillary leakage, and migration of inflammatory cells.
Alternate Names
The International Nonproprietary Name (INN) is dexamethasone. A commonly used brand name is Ozurdex®.
How It Works
Pharmacodynamics: Dexamethasone, a potent corticosteroid, exerts its effects by binding to glucocorticoid receptors in the cytoplasm. This complex then translocates to the nucleus, modulating gene expression and ultimately suppressing inflammation. It inhibits multiple inflammatory cytokines, leading to decreased edema, fibrin deposition, capillary leakage, and migration of inflammatory cells.
Pharmacokinetics: The dexamethasone intravitreal implant is administered via intravitreal injection. The implant is biodegradable and slowly releases dexamethasone into the vitreous humor. Systemic absorption is minimal. Elimination pathways have not been fully characterized for the intravitreal implant, however, systemically administered dexamethasone is primarily metabolized in the liver and excreted by the kidneys. Specific details on the metabolism by CYP enzymes are not available for the intravitreal formulation.
Dosage
Standard Dosage
Adults:
The standard dose is one Ozurdex® implant (0.7 mg dexamethasone) administered via intravitreal injection into the affected eye. Repeat administration should be considered approximately every 6 months if the patient experiences a recurrence of symptoms and, in the physician’s judgment, may benefit without being exposed to a significant risk.
Children:
Safety and efficacy have not been established in pediatric patients. Ozurdex® is not recommended for pediatric use.
Special Cases:
- Elderly Patients: No dose adjustment is necessary.
- Patients with Renal Impairment: No dose adjustment is necessary.
- Patients with Hepatic Dysfunction: No dose adjustment is necessary.
- Patients with Comorbid Conditions: Use with caution in patients with glaucoma, a history of ocular herpes simplex, or those taking anticoagulants or antiplatelet medications.
Clinical Use Cases
The dosage recommendations for specific clinical use cases like intubation, surgical procedures, mechanical ventilation, ICU use, and emergency situations are not applicable as this is a locally administered intravitreal implant designed specifically for ophthalmic conditions.
Dosage Adjustments
No specific dosage adjustments are necessary based on renal or hepatic function, metabolic disorders, or genetic polymorphisms as systemic exposure following intravitreal administration is minimal.
Side Effects
Common Side Effects
Increased intraocular pressure, conjunctival hemorrhage, cataract, eye pain, vitreous detachment, headache, ocular hypertension.
Rare but Serious Side Effects
Endophthalmitis, retinal detachment, implant migration to the anterior chamber (especially in patients with a compromised posterior lens capsule).
Long-Term Effects
Cataract formation or progression, glaucoma.
Adverse Drug Reactions (ADR)
Severe increase in intraocular pressure requiring surgery, retinal tears or detachments, endophthalmitis.
Contraindications
Ocular or periocular infection, advanced glaucoma, non-intact posterior lens capsule (aphakia with rupture, ACIOL with rupture, etc.), hypersensitivity to any component of the product.
Drug Interactions
No formal drug interaction studies have been conducted; however, caution should be exercised in patients taking anticoagulants or antiplatelet medications due to an increased risk of conjunctival or vitreous hemorrhage. Concomitant use of other ophthalmic medications should be discussed with the ophthalmologist.
Pregnancy and Breastfeeding
Pregnancy Safety Category: C. Ozurdex® is not recommended during pregnancy unless the potential benefit justifies the potential risk to the fetus. There are limited data on the use in breastfeeding; systemic absorption is low, but caution should be exercised. It is unknown if dexamethasone from the intravitreal implant is present in human milk.
Drug Profile Summary
- Mechanism of Action: Suppresses inflammation by inhibiting multiple inflammatory cytokines.
- Side Effects: Increased intraocular pressure, conjunctival hemorrhage, cataract, eye pain.
- Contraindications: Active eye infection, advanced glaucoma, non-intact posterior lens capsule.
- Drug Interactions: Use with caution in patients taking anticoagulants or antiplatelet agents.
- Pregnancy & Breastfeeding: Not recommended unless potential benefit outweighs risk.
- Dosage: 0.7 mg intravitreal implant every 6 months (approximately) as needed.
- Monitoring Parameters: Intraocular pressure, visual acuity, cataract development.
Popular Combinations
Data on popular drug combinations specifically with Ozurdex® is limited. Concomitant use of other ophthalmic medications for glaucoma or other ocular conditions may be necessary. The decision to use concomitant medications rests with the treating ophthalmologist.
Precautions
- General Precautions: Monitor for increased intraocular pressure and signs of infection.
- Specific Populations:
- Pregnant Women: Not recommended.
- Breastfeeding Mothers: Exercise caution.
- Children & Elderly: Not recommended for pediatric use. No dose adjustment is necessary for elderly patients.
- Lifestyle Considerations: Patients may experience temporarily blurred vision after the injection and should avoid driving or operating machinery until vision clears.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Dexamethasone Intravitreal Implant?
A: 0.7 mg administered as a single intravitreal injection into the affected eye. Retreatment may be considered approximately every 6 months if needed.
Q2: How long does the Ozurdex® implant last?
A: The implant releases dexamethasone for up to 6 months.
Q3: Can Ozurdex® be used in both eyes at the same time?
A: Concurrent bilateral administration is not recommended.
Q4: What are the most common side effects of the Dexamethasone Intravitreal Implant?
A: Increased intraocular pressure, conjunctival hemorrhage, and cataract formation or progression.
Q5: Is Ozurdex® safe for pregnant or breastfeeding women?
A: Ozurdex® is generally not recommended during pregnancy or breastfeeding unless the potential benefit outweighs the risk.
Q6: Can Ozurdex® be used in patients with glaucoma?
A: Ozurdex® is contraindicated in patients with advanced glaucoma. Caution should be exercised in patients with mild to moderate glaucoma, and intraocular pressure should be closely monitored.
Q7: What should I do if a patient develops an eye infection after receiving Ozurdex®?
A: Ocular or periocular infections are a contraindication to Ozurdex®. If an infection develops after injection, prompt treatment is essential. Consult an ophthalmologist immediately.
Q8: Can the Ozurdex® implant be removed if necessary?
A: In rare cases where complications arise, such as migration to the anterior chamber or uncontrolled intraocular pressure elevation, surgical removal of the implant may be considered.
Q9: What is the difference between the dexamethasone intravitreal implant and dexamethasone eye drops?
A: The intravitreal implant provides a sustained, localized release of dexamethasone directly into the vitreous, whereas eye drops deliver dexamethasone to the surface of the eye. The implant is used for specific conditions like macular edema and uveitis, while eye drops are typically used for more superficial ocular inflammation.
Q10: How soon after the injection can a patient resume normal activities?
A: Patients may experience some blurring of vision immediately after the injection. They should avoid driving or operating machinery until their vision clears, which typically occurs within a few days. Other normal activities can generally be resumed as tolerated.
