Is Bactrim (trimethoprim/sulfamethoxazole) safe to use in patients with glaucoma?

Trimethoprim/Sulfamethoxazole (Bactrim) and Glaucoma: Safety Considerations

Trimethoprim/sulfamethoxazole (Bactrim) should be used with caution in patients with glaucoma due to rare but potentially serious risks of angle-closure glaucoma and other ocular complications. While not absolutely contraindicated, alternative antibiotics should be considered when possible for patients with pre-existing glaucoma or risk factors for angle-closure.

Mechanism of Ocular Complications

• TMP-SMX can cause idiosyncratic reactions leading to:
  • Supraciliary choroidal effusion
  • Forward displacement of the lens-iris diaphragm
  • Anterior chamber shallowing
  • Secondary angle-closure glaucoma 1
  • Transient myopic shift (up to 6 diopters reported) 2

Risk Factors Requiring Special Consideration

Patients with the following characteristics are at higher risk for TMP-SMX induced angle-closure glaucoma:

• Pre-existing narrow anterior chamber angles
• Family history of angle-closure glaucoma
• Hyperopia
• Advanced age
• Asian ethnicity 3

Recommendations for Clinical Practice

For Patients Without Glaucoma:

1. Consider baseline ophthalmologic examination including intraocular pressure measurement before initiating TMP-SMX in high-risk patients
2. Educate patients about warning signs of angle-closure glaucoma:
   • Severe eye pain
   • Headache
   • Nausea/vomiting
   • Blurred vision
   • Halos around lights
3. Instruct patients to seek immediate ophthalmologic care if these symptoms develop

For Patients With Pre-existing Glaucoma:

1. Consider alternative antibiotics when possible:

   • Fluoroquinolones (moxifloxacin 0.5% or gatifloxacin 0.3%) are recommended as first-line alternatives for broad-spectrum coverage 3
   • For prophylaxis in specialized cases, polymyxin B with a fourth-generation fluoroquinolone may be considered 3

2. If TMP-SMX must be used:

   • Schedule close monitoring with ophthalmology during treatment
   • Consider more frequent IOP measurements
   • Lower threshold for discontinuation if any ocular symptoms develop

Management of TMP-SMX Induced Angle-Closure Glaucoma

If angle-closure glaucoma develops:

1. Immediately discontinue TMP-SMX
2. Initiate treatment with:
   • Topical steroids
   • Ocular hypotensive medications
   • Cycloplegic agents 3, 2

Important Caveats

• Onset can be rapid - symptoms may develop within days of starting the medication 4, 5
• In most cases, discontinuation leads to resolution of symptoms
• However, rare cases of permanent vision loss have been reported despite early diagnosis and drug withdrawal 4
• TMP-SMX can also cause other ocular complications including bilateral anterior uveitis 5

Alternative Considerations

When TMP-SMX is strongly indicated (e.g., for Pneumocystis prophylaxis in immunocompromised patients), the benefits may outweigh the risks even in patients with glaucoma 6. In such cases, close ophthalmologic monitoring is essential.

For bacterial keratitis, fluoroquinolones are generally preferred over TMP-SMX, as they have been shown to be effective and have FDA approval for this indication 6.