A Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Trial of Extract Sceletium tortuosum (Zembrin) in Healthy Adults

Abstract Objectives: The objective of the study was to evaluate the safety and tolerability of two doses (8 mg and 25 mg once daily) of a 2:1 standardized extract of the South African medicinal plant Sceletium tortuosum (L.) N.E. Br., trademarked Zembrin,® in healthy adult volunteers over a three-month period. Design: This was a randomized, double-blind, parallel-group, placebo-controlled single center study. Setting: Tiervlei Trial Centre, Karl Bremer Hospital, Bellville, Cape Town, South Africa. Participants: The study took place between February 2 and July 27, 2009. Thirty-seven healthy adults were recruited from the general population. Intervention: Participants were randomized to receive either one of two doses of study medication, or an identical placebo, taken once daily for 3 months. Of the 37 subjects, 12, 12, and 13 subjects received 8 mg extract Sceletium tortuosum (Zembrin), 25 mg extract Sceletium tortuosum (Zembrin), and placebo treatment, respectively. Outcome measures: No efficacy variable...