Given the low propensity for fidaxomicin to disrupt colonic flora, it may be hypothesized that its greatest benefit would be for use as first-line therapy in patients with a high risk of CDI recurrence prior to disruption of colonic flora with the treatment of vancomycin or metronidazole. A clinical prediction tool is needed to identify patients at high risk of CDI recurrence who would most benefit from initial fidaxomicin therapy. However, clinically relevant prediction tools are not currently used.19
Evidence exists that demonstrates the role of fidaxomicin for the treatment of recurrent CDI episodes. Cornely and colleagues pooled data from the 2 NI trials that led to the approval of fidaxomicin (n = 1,164).3,4,20 Of these, 128 participants had a recent CDI episode prior to study enrollment. For the treatment of first recurrence, 20% of patients treated with fidaxomicin experienced a second recurrence within 28 days compared with 36% of vancomycin patients (P = .045). Similarly, fewer fidaxomicin patients experienced an early recurrence within 14 days of treatment than with vancomycin for early recurrence within 14 days of treatment (8% vs 27%, respectively; P = .003).
Limitations of Fidaxomicin
One limitation of fidaxomicin is the paucity of data existing for its use in severe, life-threatening CDI, and it is currently not recommended in this indication.18 The main limitation behind the use of fidaxomicin is cost. The average wholesale price of a 10-day course of therapy of fidaxomicin is $3,360 compared with $1,273 for vancomycin capsules, $32 for compounded vancomycin oral solution, and $21 for oral metronidazole.21,22 Despite the price, cost-analysis studies have found that fidaxomicin compared with oral vancomycin is cost-effective for clinical cure rates and recurrences.23,24 Fidaxomicin also was found to be cost-effective in patients with mild-to-moderate CDI and in those using concomitant antibiotics.23 Given that 2 studies demonstrated that fidaxomicin has lower recurrence rates than that of oral vancomycin, the economical use of fidaxomicin would be of most benefit to patients at highest risk for CDI recurrence.3,4
Conclusion
In light of increased CDI treatment failure, recurrence rates, and virulence of CDI, fidaxomicin is an emerging treatment strategy. Through 2 pivotal trials, fidaxomicin has been shown to be a safe and effective first-line agent for CDI.3,4 New U.S. clinical guidelines for CDI are expected to be published in spring 2016, which will likely include the recommendation for fidaxomicin use in recurrent CDI. Current evidence suggests the most cost-effective use of fidaxomicin is in patients at highest risk of CDI recurrence.
