From the Guidelines
Yes, a patient with a penicillin allergy can safely use Polytrim (polymyxin B and trimethoprim) eye drops, as Polytrim contains no penicillin-related compounds. The mechanisms of action of polymyxin B and trimethoprim are completely different from penicillin's, which works by interfering with bacterial cell wall synthesis. There is no cross-reactivity between penicillin and either component of Polytrim, making it a safe option for penicillin-allergic patients 1.
When using Polytrim eye drops, patients should typically apply 1 drop in the affected eye(s) every 3-4 hours for 7-10 days, or as directed by their healthcare provider. It's essential to wash hands before application, avoid touching the dropper tip to any surface, including the eye, and complete the full course of treatment even if symptoms improve before finishing.
The Dutch Working Party on Antibiotic Policy (SWAB) guideline for the approach to suspected antibiotic allergy suggests that most patients who report a β-lactam allergy are not truly allergic, and the risk of cross-reactivity is smaller than previously assumed 1. This guideline supports a more liberal approach towards patients with a suspected antibiotic allergy, which may result in the use of smaller spectrum antibiotics with fewer side effects, less toxicity, and potentially lower risks of antibiotic resistance.
In the context of penicillin allergy, it's crucial to note that the risk of recurrence of an allergic reaction upon re-exposure to the antibiotic depends on several factors, including the time elapsed since the index reaction and the nature of the index reaction 1. However, Polytrim's composition and mechanism of action make it a safe choice for patients with a penicillin allergy.
Key points to consider:
- Polytrim contains no penicillin-related compounds
- No cross-reactivity between penicillin and Polytrim components
- Safe to use in patients with a penicillin allergy
- Follow the recommended dosage and administration guidelines
- Complete the full course of treatment even if symptoms improve before finishing 1.
From the FDA Drug Label
CONTRAINDICATIONS Polymyxin B Sulfate and Trimethoprim Ophthalmic Solution is contraindicated in patients with known hypersensitivity to any of its components. The patient's allergy to penicillin does not directly relate to the components of Polytrim (polymyxin B and trimethoprim) eye drops.
- The key issue is whether the patient has a hypersensitivity to polymyxin B or trimethoprim.
- Since there is no information about the patient being allergic to polymyxin B or trimethoprim, and penicillin allergy is not relevant to the use of Polytrim,
- The patient can use Polytrim eye drops if they are not allergic to its components, polymyxin B or trimethoprim 2.
From the Research
Patient Allergy Considerations
- A patient with a penicillin allergy can be considered for the use of Polytrim (polymyxin B and trimethoprim) eye drops, as there is no direct cross-reactivity between penicillin and the components of Polytrim 3.
- The components of Polytrim, polymyxin B and trimethoprim, are not beta-lactam antibiotics like penicillin, and therefore, the risk of cross-reactivity is minimal.
Mechanism of Action and Safety
- Polytrim works by inhibiting protein synthesis in bacteria, which is a different mechanism of action compared to penicillin, which inhibits cell wall synthesis 3.
- Studies have shown that patients with a penicillin allergy can safely use cephalosporins, which are also beta-lactam antibiotics, with a low risk of cross-reactivity 4, 5, 6, 7.
- However, it is essential to note that Polytrim is not a cephalosporin, and its safety in patients with penicillin allergy is not directly related to the safety of cephalosporins.
Clinical Efficacy and Safety
- A study comparing the efficacy of Polytrim and moxifloxacin in the treatment of bacterial conjunctivitis found that moxifloxacin was more effective and faster in reducing symptoms 3.
- However, this study did not specifically address the safety of Polytrim in patients with penicillin allergy.
- In general, the use of Polytrim in patients with penicillin allergy is considered safe, but it is crucial to monitor patients for any signs of allergic reactions or adverse effects.