echinacea

Findings:

Echinacea significantly reduced monthly RTI occurrence (RR 0.68), the number of patients with ≥1 RTI (RR = 0.75), risk of recurrent infections (RR = 0.60), RTI complications (RR = 0.44), and the need for antibiotic therapy (RR = 0.60), with total antibiotic therapy days reduced by 70%. Alcoholic extracts from freshly harvested Echinacea purpurea were the strongest, with an 80% reduction of antibiotic treatment days (IRR 0.21). An equal number of adverse events occurred with Echinacea and control treatment, suggesting Echinacea can safely prevent RTIs and associated complications, thereby decreasing the demand for antibiotics.

Participants:

5652 subjects from 30 clinical trials (39 comparisons) studying Echinacea for the prevention or treatment of RTIs.

Dosage:

Alcoholic extracts from freshly harvested Echinacea purpurea were the strongest, with an 80% reduction of antibiotic treatment days (IRR 0.21 [95% CI 0.15-0.28]). Relevant differences exist between Echinacea preparations.

Study Quality Assessment:

Meta-analysis of 30 clinical trials (39 comparisons) involving 5652 subjects. Searched EMBASE, PubMed, Google Scholar, Cochrane DARE and clinicaltrials.gov. Conflict of interest statement provided: R.S., W.C.A. and S.L.J. received honoraria from A.Vogel AG Switzerland for consulting work; G.H. received honoraria for statistical evaluation. Figures mentioned include Funnel plots and Abbey plots (related to bias assessment in meta-analyses).

All Effects:

Findings:

This review details Echinacea purpurea's phytochemistry (notably alkamides, caffeic acid derivatives, polysaccharides), pharmacology, and analysis methods. It highlights its traditional and studied immunostimulatory and anti-inflammatory properties, along with other reported activities such as antianxiety, antidepressant, cytotoxic, antimutagenic, antioxidant, antibacterial, antiviral (including against influenza viruses), and larvicidal effects. The review emphasizes that clinical trial findings, particularly concerning efficacy for cold symptoms and the nature of side effects (which range from none to serious ones like abdominal pain or angioedema), are controversial, underscoring the need for further research to elucidate its mechanisms of action.

Participants:

The review paper discusses various studies involving human participants, such as 'patients' in clinical trials (e.g., '108 patients' in a trial for colds), 'healthy volunteers' (including 'six healthy volunteers' for lozenge pharmacokinetics and 'healthy nonsmoking volunteers' for CYP enzyme studies). Animal models mentioned include 'rats' (e.g., 'healthy rats', 'male rats' for prolactin secretion studies), 'mice' (e.g., 'Swiss mice', 'normal, leukemic, and aging mice', 'female mice' for toxicity studies), and 'rabbits'.

Dosage:

The review mentions various dosages from different studies: 'plant root powder was administered to the male rats (in two doses: 30 and 100 mg/kg)', 'Dried root powder of the plant, administered to the mice (30-100 mg/kg)', 'High concentrations of the plant (8 mg/ml) reduced sperm motility'. Toxicity studies reported 'LD50 value was calculated as 2500 mg/kg in an intraperitoneal injection of the polysaccharide fraction of the plant in female mice', and for plant juice, 'LD50 values of oral... more than 30 g/kg... in mice, and 15 g/kg... in rats', and intravenous administration 'more than... 10 g/kg in mice, and 5 g/kg in rats'. Lozenges with E. purpurea extract showed effects where 'All the doses significantly decreased proinflammatory cytokines'.

Study Quality Assessment:

This text is a review article. It references various study types including 'clinical trials' (some described as 'randomized blinded trial', 'double-blind, placebo-controlled cross-over study'), 'in vivo studies', and 'in vitro studies'. Analytical methods like 'high-performance liquid chromatography (HPLC)', 'LC-MS/MS', 'capillary electrophoresis (CE)', and 'micellar electrokinetic chromatography (MEKC)' are mentioned for phytochemical analysis. The review notes that findings of clinical trials are 'controversial', 'many questions remain unanswered', and cites another review indicating that some studies on common cold treatment 'failed to meet the criteria of experimental design'.

All Effects:

Findings:

This systematic review of nine clinical trials concluded that Passiflora incarnata preparations generally reduced anxiety levels, with the effect being less evident in people with mild anxiety symptoms. No adverse effects, including memory loss or collapse of psychometric functions, were observed in the reviewed studies. The review suggests Passiflora incarnata may be helpful in treating some symptoms in neuropsychiatric patients, potentially alleviating stress reactivity, insomnia, and depression-like behaviors, with an anti-anxiety effect comparable to drugs like oxazepam or midazolam in some contexts.

Participants:

Systematic review of 9 clinical trials. Participants in the included studies were adults (no less than 18 years old). The vast majority of participants in these trials were healthy; one study included participants with a diagnosis of Generalized Anxiety Disorder (GAD). Sample sizes in the individual reviewed studies ranged from N=16 to N=128.

Dosage:

Dosages in the 9 reviewed clinical trials varied widely and included: 45 drops/day of extract; 700 mg/5 mL of syrup; 500 mg tablets; 260 mg pill; 192 mg of P. incarnata extract; 40 drops/day of extract; an infusion (2 g in 250 mL water); 1000 mg. Administration was typically oral. The duration of the studies included in the analysis varied from a single day up to 30 days.

Study Quality Assessment:

Systematic review of 9 randomized clinical trials (RCTs). Scientific databases (PubMed, ClinTrials.gov, Embase) were searched up to October 22, 2019. Data extraction followed PRISMA guidelines (no study protocol registration). The Cochrane Collaboration’s tool was used for assessing risk of bias (ROB) of the included studies; three studies were assessed as low quality (<5 points ROB), while six had higher scores (≥5 points ROB). The majority of the analyzed studies (7/9) were double-blind (DB), with some being single-blind (SB) or cross-over. Acknowledged limitations of the review include the small number of studies (9), small sample sizes in the primary studies (ranging from 16 to 128 persons), high heterogeneity precluding meta-analysis, and sometimes a lack of information on which part of the plant was used. Funding source for the review project was mentioned.

All Effects:

Findings:

This systematic review assesses safety data for orally used Echinacea preparations (Echinacea purpurea, Echinacea angustifolia, Echinacea pallida), emphasizing that safety data are product-specific. Key findings include: standardized E. purpurea preparations showed no significant in vivo inhibition of human CYP2D6 and CYP3A4 (though in vitro results using liver microsomes are contradictory); adverse events reported during clinical trials were generally mild and mostly without causality; long-term use (up to 6 months) is considered safe. Contraindications for autoimmune diseases, immune-suppression, and use during pregnancy are questioned, with a literature review finding no association with an increased risk for major or minor malformations during organogenesis; overall, evaluated Echinacea preparations are considered well-tolerated in children and adults.

Participants:

The review covers studies involving humans (including pregnant and nursing women, children, and adults) and mice (for embryonic angiogenesis studies).

Dosage:

Long term studies with continuous ingestion of different Echinacea preparations up to 6 months.

Study Quality Assessment:

Systematic review of available literature. Assesses data from pharmacokinetic herb-drug interaction studies (in vivo and in vitro using liver microsomes, noting contradictory results for the latter), clinical trials, and long-term studies (continuous ingestion up to 6 months). The document type is 'Review'.

All Effects: