Study Design
The current study is a triple-blind, placebo-controlled, cross-over,
4-week clinical trial with a 4-week washout period. Details and
procedures of the study were completely explained to patients through an
interview, consent was obtained before the start of study treatment.
This clinical trial was conducted in accordance with the ethical
principles that have their origin in the Declaration of Helsinki, and
that are consistent with Good Clinical Practice (GCP) and the applicable
regulatory requirements. Moreover, the study is in compliance with the
regulations of Iran and approved by an independent ethics committee of
Mashhad University of Medical Sciences, Mashhad, Iran (ethics committee
reference number and approval date: IR.MUMS.REC.1394.705, 2016-02-27).
This clinical trial was registered at the Iranian Registry of Clinical
Trials (www.irct.ir, IRCT registration number
and date: IRCT20130418013058N8, 2018-04-22). In the first step, 51
hypertensive patients were allocated into celery and placebo groups
(Figure 1). The patients received four capsules per day (2 capsules
every 12 hours before meal) for 4-weeks as a supplement to their usual
medication regimen. After a 4-week washout period, in the second step,
the patients were crossed over into another medication group. Therefore,
the patients who had received celery extract in the first step received
placebo capsules after the cross-over, and those who had received
placebo in the first step received celery extract capsules in the second
step. The participants were not allowed to change their medication
regimens or lifestyles during the study. Patient compliance with
medication and trial process was assessed through weekly phone calls and
at each visit to the physician.