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FDA Panel Questions Long-Term Efficacy of Blood Pressure Drug Droxidopa
Treatment lacks evidence of durability, reviewers say (January 10)
Reviewers on the FDA’s Cardiovascular and Renal Drug Advisory Committee have questioned the long-term efficacy of an investigational agent, droxidopa (Chelsea Therapeutics International), for the treatment of neurogenic orthostatic hypotension (NOH) — a rare, chronic form of low blood pressure that occurs on standing. The reviewers’ opinion was posted ahead of a scheduled Jan. 14 meeting to consider approval of the drug.
Arguments in favor of approval include “strong evidence” from one randomized controlled trial that droxidopa confers at least 1 week of symptomatic benefit, the panel members note. During this period, the drug provided a significant benefit (P < 0.001), as measured by the Orthostatic Hypotension Symptom Assessment (OHSA), a questionnaire designed to evaluate symptoms that are common in patients with symptomatic orthostatic hypotension as well as the effect of those symptoms on the patient’s ability to function.
However, arguments against approval include a lack of evidence that the symptomatic benefit of droxidopa extends beyond 1 week. According to the reviewers, two pivotal studies, while showing “the slightest of favorable trends” on OHSA, did not demonstrate a clinical or symptomatic benefit after 2 weeks and 3 months, respectively, of chronic use followed by a 2-week randomized withdrawal period.
Further, systolic blood pressure data failed to provide evidence of “consistency of effect,” the reviewers say. In fact, there was no difference between droxidopa and placebo in standing blood pressure in the two pivotal studies.
“The lack of evidence of durability is particularly concerning,” the reviewers write. “Patients should not be exposed to a drug chronically unless benefit is established over a reasonable amount of time — at least three months.”
The FDA is not obligated to follow the advice of its advisory committees, but it usually does so.