Tobramycin and dexamethasone are two medications that are sometimes combined to treat medical conditions such as bacterial infections of the eye that involve inflammation. Dexamethasone is a steroid hormone, a type of compound that can reduce inflammation. Tobramycin is an antibiotic that tends to be effective against many species of bacteria, especially streptococci and staphylococci. For direct delivery into the eye, this drug combination usually comes in the form of liquid eye drops.
The types of infection that this combination can be used to treat is largely confined to those caused by bacteria. Cases where infections can be a result of viruses, including herpes, should not usually be treated with this drug. Additionally, infections from fungus or a type of bacteria known as mycobacteria normally require other treatments as well. These infections may actually be made worse if either tobramycin and dexamethasone is used because of the way that steroids can inhibit immune responses.
Careful dosing of tobramycin and dexamethasone can usually assist in treating infections quickly. Many individuals taking this medication apply one or two drops to the corner of each eye every two hours for the first day or two. After these initial larger doses, individuals may limit their use to one or two doses every four to six hours. Often, as the condition of the eye improves, the number of times that the medication is applied each day can be decreased. Usually, individuals use a complete 20 milliliter (mL) bottle of tobramycin and dexamethasone before stopping therapy, because ending it early can allow the infection to return.
Like most medications, this drug can have potential side effects. Some of the risks of tobramycin and dexamethasone include swollen or irritated eyelids, as well as sensitive eyes. Studies performed by the manufacturer of this medication have found that these effects only occur in around 4% of individuals. Very rarely, more serious side effects can occur. These problems include the development of glaucoma, cataracts, nerve damage, and slower healing of infection-related wounds.
Secondary infections are an uncommon, but possible, risk of tobramycin and dexamethasone. Fungal infections or subsequent bacterial infections can occur in some individuals after taking different steroid and antibiotic combinations, in part because steroids suppress the immune system. Ulceration, or damage, to the cornea of the eye that remains unresponsive to treatment can be a sign of this infection.
