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Level of infection dictates choice of topical vs. systemic anti-infective
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While topical medications are often sufficient for treating various ocular infections, certain conditions warrant the use of systemic anti-infectives. Typically, the level of tissue that is infected will determine whether to prescribe a topical or oral medication.
Infections of the cornea and conjunctiva and any superficial lid infections, such as blepharitis, would require topical medication, virtually ruling out oral anti-infectives, said Bruce E. Onofrey, OD, FAAO, who is responsible for primary care eye services at Lovelace Medical Center in Albuquerque, N.M. “If you can access the condition with a topical antibiotic, it’s actually better to treat it topically,” he said. “For example, with infectious keratitis, there are no blood vessels in the cornea, so there is no way to access it systemically.”
Infections that occur in the deeper tissues of the ocular adnexa or the lacrimal system should be treated systemically. When determining whether or not to use orals, Southern California College of Optometry president Les Walls, OD, MD, said to keep a basic rule of thumb in mind. “Use the safest drug and the safest route of administration to do the job,” he advised. “If a topical won’t do it, then a systemic agent is the answer.”
Before prescribing orals
Before a practitioner makes the decision to prescribe an oral medication, he or she should take a thorough case history, focusing on the patient’s overall health. This history should include a list of any allergies and other medications that the patient may already be taking.
“When you use systemic medications, you can affect many systems of the body, and you want to make sure that the patient isn’t going to have an allergic reaction or any other adverse reaction,” said David Geffen, OD, who is responsible for primary eye care services at Vision Surgery and Laser Center in San Diego. “You want to make sure that you understand what his or her other medications are and how the medication you’re going to prescribe will react with them.”
Dr. Onofrey believes a thorough social and medical history should be obtained before initiating therapy. After the case history has been established, one-on-one counseling with the patient is important to ensure that the medication is taken correctly. “Be certain they finish their medication, and make them aware of potential side effects and adverse effects of the drug so they can report any occurrence,” he said.
Side effects: What to expect
The decision to change or discontinue a systemic medication depends heavily on the patient’s side effects. Discontinue the medication if the person is allergic or if he or she has been taking it for a sufficient period of time to treat the infection when the side effects begin, Dr. Walls said. “If they’re not far enough along and they are having substantial side effects, you have to switch medications to finish the treatment,” he said.
Some minor side effects can often be tolerated well if the patient is warned about the possibility ahead of time, Dr. Walls said.
Dr. Geffen said that while side effects such as nausea, diarrhea and, possibly, some light sensitivity should be noted, they are not usually considered serious enough to discontinue the medication altogether. Dr. Onofrey cautioned that diarrhea caused by pseudomembranous colitis is a serious condition.
If the side effects are particularly bothersome to the patient, switching medications is preferable to prescribing additional anti-infectives to be used simultaneously. “I believe that less is best,” Dr. Geffen said. “I’d rather get by with the minimal amount of medications you can get away with for effective treatment than just load patients up on several things and try to counteract the first problem.”
The penicillins and cephalosporins can produce allergic reactions as well as gastrointestinal upset, Dr. Onofrey said. Because a common side effect of drugs such as doxycycline and the tetracyclines is an increased level of light sensitivity, those patients should be advised to stay out of the sun to prevent sunburn and rash, he added.
Prescribing the correct anti-infective
In addition to safety and effectiveness, practitioners should consider the cost of the medication and determine if there is a generic version that will do the job, Dr. Walls said.
Dr. Onofrey said his first-line therapy for ocular infections such as preseptal cellulitis, dacryocystitis and dacryoadenitis would be penicillinase-resistant penicillin including dicloxacillin sodium, cloxacillin sodium, and Augmentin (amoxicillin and clavulanate, Smith Kline Beecham). When a patient exhibits allergic symptoms to these medications, he recommends first-generation cephalosporins such as Keflex (cephalexin, Lilly) for staphylococcal and streptococcal infections and Ceclor (cefaclor, Lilly) or another second-generation cephalosporin for Hemophilus gram-negative infections.
According to Dr. Onofrey, 3% of penicillin-sensitive patients are also sensitive to the cephalosporins. In cases like this, the macrolide antibiotics clarithromycin or azithromycin can be used. These agents are also useful for treating chlamydial infections, with a second-line therapy of erythromycin or tetracycline. He also suggested tetracycline for chronic marginal staphylococcal blepharitis and doxycycline for acne rosacea. Any of the antivirals, such as acyclovir, famcyclovir or valacyclovir, could be used to treat herpes simplex or zoster, he added, while considering the age of the patient exhibiting this type of infection.
“I am a little more resistant to treating people under the age of 50 with one of those expensive agents, because the incidence of postherpetic trigeminal neuralgia is really most significant in people older than 50. If a young person who is not immunocompromised has no ocular involvement, I would probably not consider treating him or her with those antivirals. It’s unnecessary.”
Dr. Onofrey suggested checking on the patient midway through the treatment period to ensure that the medication is producing the desired effect and not causing any problems. “If necessary, cultures should be done to determine if the antibiotic is the right drug to use in that particular patient.”
For Your Information:
- Bruce E. Onofrey, OD, RPh, may be reached at Lovelace Medical Center, Montgomery Eye Clinic, 9101 Montgomery Blvd., NE, Albuquerque, NM 87111; (505) 275-4226; fax: (505) 275-4203; e-mail: Eyedoc3@aol.com.
- Les Walls, OD, MD, may be reached at the Southern California College of Optometry, 2575 Yorba Linda Blvd., Fullerton, CA 92831; (714) 449-7450; fax: (714) 526-3907; e-mail: leswalls@scco.edu.
- David Geffen, OD, can be contacted at Vision Surgery and Laser Center, 8910 University Center La., Ste. 800, San Diego, CA 92122; (619) 455-9950; fax: (619) 455-9954. Drs. Onofrey, Walls and Geffen have no direct financial interest in the products mentioned in this article, nor are they paid consultants for any companies mentioned.