Managing glaucoma in pregnancy bears discussion

January 15, 2014

Glaucoma medications should be used judiciously in women of childbearing age as they may pose risks to the infants of pregnant or nursing patients.

Take-home:

Glaucoma medications should be used judiciously in women of childbearing age as they may pose risks to the infants of pregnant or nursing patients.

 

Dr. Wright

By Nancy Groves; Reviewed by Martha M. Wright, MD

Minneapolis-Glaucoma is often thought of as a disease of aging, but it can affect patients who are much younger and more interested in starting a family than planning for retirement. With women in this age group, ophthalmologists should take extra time before reaching for the prescription pad.

“Glaucoma medication exposure is of concern to our patients and to us, not only in pregnancy, but during labor and delivery and in nursing patients,” said Martha M. Wright, MD, Haven Professor of Glaucoma, Department of Ophthalmology, University of Minnesota, Minneapolis.

“My rule of thumb in treating women of childbearing age is that when you start a medication for glaucoma, you should discuss the risks of these medications with pregnancy even if they are not pregnant or planning to be pregnant at the time,” she said. “Revisit the topic periodically. In some cases, we have the advantage of being told in advance that a pregnancy is being planned so that the ophthalmologist, the patient, and the obstetrician can work together to come up with the best possible plan.”

Management approach

Choosing the best management approach is complicated by the fact that many questions about glaucoma medication use during pregnancy are unanswered.

“We have limited information to help us,” Dr. Wright said, explaining that animal studies do not necessarily translate into risks for humans, and there have been few studies of glaucoma medications in pregnant women since they are unlikely to enroll in drug studies.

What is known is that the dose and timing of medication can be important, with an earlier exposure in pregnancy having a different outcome than later exposure, Dr. Wright said.

However, it’s unclear how the customary eye drop-size dose of a medication used in clinical practice relates to the much larger doses used in pregnancy risk studies.

The best available guide to help physicians assess the risk of glaucoma medications is the FDA Use in Pregnancy ratings.

·      Category A is for drugs for which no risk was shown in well-controlled studies.

·      In Category B, there is no evidence of risk in humans. Either animal findings show risk but human findings do not; or, if no adequate human studies have been done, animal findings are negative.

·      A Category C drug is one for which risk cannot be ruled out but potential benefits may justify the potential risk.

·      Category D drugs show positive evidence of risk, but again, potential benefits may outweigh potential risk.

·      Category X medications are contraindicated in pregnancy.

How should the ophthalmologist use these guidelines?

“The ‘obvious’ answer is to pick only category A drugs for pregnant patients, but unfortunately there aren’t any,” Dr. Wright said.

The only readily available drug in FDA Category B is brimonidine tartrate 0.1%, 0.15%, or 2% (Alphagan, Allergan), and most of the routinely prescribed glaucoma agents are in Category C.

While high doses of brimonidine in animal studies did not cause fetal damage, it is known that this drug, secreted in breast milk, causes apnea in human infants.

“It’s recommended that if you have a patient on brimonidine, that it be stopped prior to delivery,” Dr. Wright said.

Prostaglandin analogs are a mainstay of glaucoma treatment, but they are Category C drugs in which risks cannot be ruled out. This class of medication is used to induce labor at much higher doses, and the prostaglandins are embryocidal at higher doses in animals; no human studies have been performed.

Beta-blockers have been used systemically for many years to treat hypertension in pregnant women.

However, there may be an association with small for gestational age births, preterm births, and increased perinatal mortality in patients taking oral beta-blockers at doses hundreds to thousands of times the human dose by weight. Beta-blockers are Category C medications.

Beta-blockers are also of concern in nursing women, as these medications are actively secreted and concentrated in breast milk.

“Babies of mothers taking these medications should be monitored for apnea and bradycardia,” Dr. Wright said.

Carbonic anhydrase inhibitors (CAIs) are also Category C medications and are known to cause fetal malformation in animal studies at high doses. However, a study in which pregnant women were prescribed acetazolomide (Diamox) for treatment of intracranial hypertension did not show any adverse effects on the fetus.

Regardless of the medication prescribed to a pregnant or nursing patient, one of the goals should be to minimize systemic absorption with a punctal occlusion method.

“And if either you or your patient are not willing to use medication during pregnancy, then laser trabeculoplasty can be used as a temporizing measure,” Dr. Wright said.

“Or, if you can do it in advance, some surgical options may be best for these patients. But remember, you want to be sure that your patient is not pregnant at the time that you use an antifibrotic because these are Category X,” she continued.

Birth defects and miscarriages have been reported with topical use of 5-fluorouracil on mucous membranes, and mitomycin-C has known teratogenic effects in animals; safe use in pregnant women has not been established.

 

Martha M. Wright, MD

P: 612/625-4400

E: wrigh004@umn.edu

Dr. Wright did not report any financial interests.

 

 

 

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