From the Guidelines
Fidaxomicin is generally well-tolerated, but it can cause several adverse effects, including gastrointestinal disturbances, hypersensitivity reactions, and less frequently, anemia, neutropenia, and elevated liver enzymes 1. The most common side effects of fidaxomicin include:
- Gastrointestinal disturbances such as nausea, vomiting, abdominal pain, and gastrointestinal bleeding
- Constipation
- Hypersensitivity reactions Less frequently reported adverse effects include:
- Anemia
- Neutropenia
- Elevated liver enzymes
- Headache and dizziness Fidaxomicin has minimal systemic absorption, which contributes to its favorable safety profile compared to other antibiotics used for Clostridioides difficile infections 1. The localized action in the gut means that systemic side effects are less common. However, patients with a history of gastrointestinal disorders should be monitored closely when taking this medication. The standard dosage is 200 mg taken orally twice daily for 10 days, and patients should complete the full course even if symptoms improve before completion to prevent recurrence of infection 1. It is essential to note that the recommendations for the use of fidaxomicin are based on the latest guidelines, which suggest that fidaxomicin is a preferred treatment option for initial and recurrent Clostridioides difficile infection episodes 1.
From the FDA Drug Label
The most common selected adverse reactions occurring in ≥5% of pediatric patients treated with DIFICID in the Phase 3 trial are listed in Table 3
System Organ Class | DIFICID(N=98) | Vancomycin(N=44) Adverse Reaction | n (%) | n (%)
- Includes abdominal pain, abdominal pain lower, and abdominal pain upper † Includes alanine aminotransferase increased, aspartate aminotransferase increased, and hepatic enzyme increased ‡ Includes rash, rash follicular, rash maculo-papular, and exfoliative rash Gastrointestinal Disorders | Abdominal pain* | 8 (8.2) | 9 (20.5) | Vomiting | 7 (7.1) | 6 (13.6) | Diarrhea | 7 (7.1) | 5 (11.4) | Constipation | 5 (5.1) | 1 (2.3)
General Disorders and Administration Site Conditions | Pyrexia | 13 (13.3) | 10 (22.7) Investigations | Aminotransferases increased† | 5 (5.1) | 1 (2.3) Skin and Subcutaneous Tissue Disorders | Rash‡ | 5 (5.1) | 1 (2.3)
The following adverse reactions were reported in <5% of pediatric patients taking DIFICID in clinical trials: Skin and Subcutaneous Tissue Disorders: urticaria, pruritus
Post Marketing Experience The following adverse reactions have been identified during post-approval use of DIFICID. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure Hypersensitivity reactions (dyspnea, angioedema, rash, pruritus)
The adverse effects of fidaxomicin include:
- Gastrointestinal disorders: abdominal pain, vomiting, diarrhea, constipation
- General disorders and administration site conditions: pyrexia
- Investigations: aminotransferases increased
- Skin and subcutaneous tissue disorders: rash, urticaria, pruritus
- Hypersensitivity reactions: dyspnea, angioedema, rash, pruritus 2 2
From the Research
Adverse Effects of Fidaxomicin
- The adverse-effect profile of fidaxomicin is comparable to that of vancomycin 3
- Fidaxomicin has been generally well tolerated, with the most common adverse effects reported as mild gastrointestinal complaints 4, 5
- The most common adverse effects of fidaxomicin are mild gastrointestinal complaints, but the specific details of these complaints are not provided in the studies 4, 5
Comparison with Vancomycin
- Fidaxomicin has been shown to be noninferior to vancomycin in the management of mild-to-moderately severe CDI 3
- Fidaxomicin treatment was noninferior to vancomycin treatment with regard to clinical cure rates and was associated with statistically significantly lower C. difficile infection recurrence rates and statistically significantly higher global cure rates than vancomycin 6
Special Considerations
- Fidaxomicin appears to have minimal need for renal or hepatic adjustments and minimal concerns for drug-drug interactions 5
- The use of concomitant antibiotics during fidaxomicin treatment was associated with a lower cure rate and an extended time to resolution of diarrhea, but fidaxomicin was still more effective than vancomycin in achieving clinical cure in the presence of concomitant antibiotic therapy 7