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Tobramycin, dexamethasone used for postop infection, inflammation
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TobraDex (tobramycin dexamethasone, Alcon) is a widely used suspension drop or ointment for postoperative prophylaxis for infection and postsurgical inflammation. Because tobramycin is effective against a wide range of bacteria, this combination drug is also an effective tool against bacterial conjunctivitis with moderate to severe inflammation of the ocular tissue. The dexamethasone is a strong steroid that suppresses the body's autoimmune responses, inhibiting inflammation of the ocular tissue.
Tobramycin provides coverage for many bacterial strains, including:
- Staphylococcus aureus,
- Staphylococcus epidermidis,
- Streptococcus pneumoniae,
- Pseudomonas aeruginosa,
- Escherichia coli,
- some Neisseria species
- Hemophilus influenzae and
- a few other less common bacteria that cause anterior segment infection.
Reserve steroids
Dexamethasone is a corticoid (steroid) that inhibits the body's defense mechanism, which may slow healing and inhibit the natural defenses allowing bacteria, fungi or virus to multiply more rapidly. The message is this: if you are unsure of the diagnosis, reserve steroids until the cause of the infection is known.
Intraocular pressure (IOP) should be monitored when using a medication with dexamethasone. Steroid responders can have an increase in IOP after using the drop or ointment for more than 7 days. Long-term treatment requires weekly IOP checks.
TobraDex suspension (tobramycin 0.3% and dexamethasone 0.1%) is preserved with 0.01% benzalkonium chloride. Because the drop is in suspension form, the patient needs to shake the bottle for 5 to 10 seconds before instilling the drop. TobraDex ointment is preserved with chlorobutanol 0.5%, with mineral oil and white petrolatum used for the vehicle to carry the drugs. The suspension is supplied in 2.5-mL and 5.0-mL bottles. The ointment comes in a 3.5-g ophthalmic tube.
Use after refractive surgery
TobraDex is commonly used four times per day for 5 to 14 days following radial keratotomy (RK).
After photorefractive keratectomy (PRK), TobraDex is used four times a day for 3 to 5 days until the epithelium has covered the cornea. A weaker steroid, FML 0.1% (fluorometholone, Allergan) or Fluor-Op (fluorometholone ophthalmic suspension, Ciba Vision) is prescribed four times per day for 1 month and tapered over the next 3 months, depending on the rate of refractive change. With long-term use of FML or Fluor-Op, monitor the IOP at least monthly and always be concerned about secondary corneal herpes simplex infection.
Laser in situ keratomileusis (LASIK) leaves most of the epithelium intact, thus there is less corneal inflammation and less chance of infection. TobraDex is usually prescribed four times a day for 4 days and discontinued. Most often, the only drops used from that point on are artificial tears.
Postop cataract surgery
TobraDex provides protection against postoperative infection and helps reduce inflammation from the surgery. The type of cataract surgery determines how often TobraDex will be used. Clear cornea surgery may require drops for only a few days after surgery. More invasive surgery can require TobraDex drops and ointment for 2 weeks and then Pred Forte (prednisolone acetate, Allergan), Vexol (rimexolone, Alcon) or Flarex (fluorometholone acetate 0.1%, Alcon) for up to 4 more weeks after discontinuing the TobraDex. Most often, the use of TobraDex is four times per day for 1 week after surgery. Then, steroid drops are used for 1 to 3 weeks, depending on the surgeon and the patient's rate of recovery.
Factors such as lid disease, patient age, IOP and anterior chamber reaction are conditions that determine how often and how long each of the medications need to be used after cataract surgery.
When infection and inflammation are present, TobraDex is an excellent ophthalmic medication to fight the infection and reduce inflammation. For the more severe cases of bacterial conjunctivitis, TobraDex can be prescribed every 2 hours during the first 48 hours and then reduced to four times per day. Ointment is often prescribed for use at bedtime to increase the time of coverage for the medications. Most often the four times daily dosage can be tapered after 4 to 5 more days of treatment and the ointment discontinued.
Most bacterial infections will show some improvement using TobraDex for 2 to 3 days. If the infection shows no improvement within 2 to 3 days, consider culturing or changing to another medication. Other antibiotic options for bacterial infections include Polytrim (trimethoprim sulfate, polymyxin B sulfate, Allergan), Ocuflox (ofloxacin, Allergan) or Ciloxan (ciprofloxacin HCl, Alcon) if the patient is not responding to treatment with TobraDex. Bacteria typically associated with pediatric infections respond well to Polytrim. Nonbacterial causes of the infection could be viral or chlamydial.
Injury, scarring
With an anterior segment injury, you need to be concerned about infection. Tobramycin is a prophylactic against infection, and dexamethasone works to reduce scarring from the inflammation caused by the injury. Burns, chemical injury, lacerations and abrasions are common injuries that require broad-spectrum antibiotic coverage and often a steroid to reduce inflammation and the risk of scarring.
TobraDex is one of the most often used ophthalmic medications in North America. Its track record has been excellent, with few reactions when used appropriately. With the growth of the refractive surgery market, we will see this medication prescribed often by both the ophthalmologist and optometrist following refractive laser correction.
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For Your Information:
- Bobby Christensen, OD, FAAO, in in private practice and lectures widely on therapeutic pharmaceutical agents. He can be reached at Heritage Park Medical Center, 6912 E. Reno, Suite 101, Midwest City, OK 73110; (405) 732-2277; fax: (405) 737-4776. Dr. Christensen has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any company mentioned.
- TobraDex is available from Alcon Laboratories, 6201 South Freeway, Fort Worth, TX 76134; (800) 757-9195; fax: (817)551-8893.