Understanding the FDA Pregnancy Risk Categories
Healthcare providers use classifications to assess potential risks to the fetus when treating conditions like glaucoma during pregnancy. The FDA's previous letter-based system is often referenced and helps guide, but does not dictate, treatment decisions. The categories are:
- Category A: No demonstrated risk to the fetus in any trimester based on adequate human studies. No glaucoma medications are in this category.
- Category B: Animal studies show no fetal risk, but human studies are lacking, or animal studies show risk, but human studies do not.
- Category C: Animal studies show fetal risk, but human studies are lacking. Use may be warranted if potential benefits outweigh risks.
- Category D: Positive evidence of human fetal risk, but use may be warranted in life-threatening situations if benefits outweigh risks.
- Category X: Studies show fetal abnormalities or toxicity, with risks clearly outweighing benefits. Contraindicated in pregnancy.
Brimonidine: The Sole Category B Glaucoma Medication (With a Caveat)
Historically, brimonidine and dipivefrine were Category B, but dipivefrine is rarely used now, making brimonidine the primary Category B option. Brimonidine lowers intraocular pressure by decreasing aqueous humor production and increasing outflow.
Although Category B status suggests lower risk, brimonidine is linked to significant CNS depression and apnea in newborns. Therefore, it's typically discontinued weeks before the due date. It's also contraindicated during breastfeeding due to the risk of infant adverse effects.
A Comparative Look at Other Glaucoma Medication Classes
Most topical glaucoma medications are classified as Category C, requiring a careful risk-benefit assessment.
Glaucoma Medication Classes and Pregnancy Considerations
| Medication Class | Example Drugs | Pregnancy Category | Key Considerations During Pregnancy |
|---|---|---|---|
| Alpha-2 Agonists | Brimonidine | B | Preferred in first/second trimesters but discontinued in the third due to neonatal CNS depression/apnea risk. Contraindicated in lactation. |
| Prostaglandin Analogues (PGAs) | Latanoprost, Travoprost, Bimatoprost | C | Potential risk of uterine contractions; generally avoided, especially early in pregnancy. |
| Beta-Blockers | Timolol, Betaxolol | C | Cross placenta; may cause fetal bradycardia/arrhythmia. Can be used in later pregnancy with monitoring. May be used cautiously during breastfeeding. |
| Carbonic Anhydrase Inhibitors (CAIs) | Dorzolamide (topical), Acetazolamide (oral) | C | Topical forms have lower systemic absorption but used with caution. Oral forms generally avoided due to potential teratogenic effects in animal studies. |
| Rho Kinase Inhibitors | Netarsudil | Not assigned (older category system) | Limited human data; avoided in pregnancy and breastfeeding. |
Comprehensive Management Strategies for Pregnant Patients
Managing glaucoma during pregnancy requires a collaborative approach with an ophthalmologist and obstetrician.
- Preconception Counseling: Discussing treatment options before pregnancy is ideal for planning, including exploring laser therapy.
- Minimize Systemic Absorption: Reduce systemic absorption of eye drops with nasolacrimal occlusion (pressing on the inner corner of the eye) for 1-5 minutes after application and keeping eyes gently closed for several minutes.
- Explore Alternative Therapies: Non-medical options like Selective Laser Trabeculoplasty (SLT) can control IOP during pregnancy. Observation may be considered for mild cases or if pressures decrease naturally.
- Tailor Treatment by Trimester: Medication use is typically limited in the first trimester (organogenesis), with brimonidine being a primary choice if needed, using risk-reduction techniques. In the second trimester, other Category C drugs like beta-blockers may be considered with monitoring. Brimonidine must be stopped in the third trimester due to neonatal apnea risk.
Conclusion
While brimonidine is often cited as the only pregnancy category B glaucoma medication, its use is not without risk, particularly late in pregnancy and during breastfeeding. Managing glaucoma in pregnant patients requires collaboration between ophthalmologist and obstetrician, careful risk-benefit assessment, strategies to minimize systemic absorption, and consideration of alternative therapies like laser treatment, to prioritize the safety of both mother and child.
For more detailed information on glaucoma management during pregnancy, refer to resources like the article on Eyes On Eyecare, "A Guide to Glaucoma During Pregnancy".
