Efficacy of a Topical Application of Ageratum conyzoides on Increasing Hair Growth and in Males and Females: A Randomised Double-blind Placebo-controlled Study

Paul Clayton^1*, Ruchitha Venkatesh², Shama², Nathasha Bogoda², Silma Subah² and Amanda Rao^3
*Correspondence: Paul Clayton, Institute of Food, Brain and Behaviour, Beaver House, 23-28 Hythe Bridge Street, Oxford OX1 2EP, UK, Tel: +44 800 644 0322, Email:

Keywords

Ageratum conyzoides • Hair loss • Hair growth • Alopecia • Topical application

Abbreviations

AG: Androgenetic Alopecia • HLR: Hair Loss Ratio • PGD2: Prostaglandin D2 • PGDS: Prostaglandin D Synthase • DHT: Dihydrotestosterone • IGF-1: Insulin-Like Growth Factor 1 • HDL: High-Density Lipoprotein • LDL: Low-Density Lipoprotein • TSH: Thyroid Stimulating Hormone • ALT: Alanine Transaminase • AST: Aspartate Aminotransferase • GGT: Gamma-Glutamyl Transferase • PGEM: Prostaglandin E Metabolite • FBC: Full Blood Count

Introduction

Alopecia is a common condition experienced by both males and females. Although not debilitating, it can cause significant psychological distress and billions of dollars are spent on hair loss treatments per year. The most common type of male and female pattern baldness is androgenetic alopecia (AGA), genetically determined androgen-induced pattern baldness (Clarke 2016). It affects up to 80% of men and 40% of women during their lifetime and although its prevalence increases over time, it can occur at almost an age.

Dihydrotestosterone has been identified as an underlying driver of AGA and inhibition of 5-alpha-reductase, an enzyme responsible for converting testosterone to dihydrotestosterone, is a recognised treatment approach [1]. Recent studies have found Prostaglandin D2 synthase (PTGDS) and its enzymatic product, PGD2 to be increased in the bald scalp of men with AGA, giving rise to new avenues of intervention [2,3].

Available treatments for AGA include surgery and pharmacological approaches utilising topical gels/creams and oral medications. The two most commonly used are Finasteride and Minoxidil. Finasteride is a type 2 5-alpha reductase inhibitor which blocks the conversion of testosterone to dihydrotestosterone and improves scalp hair growth in men by reducing DHT levels in the scalp [4]. It does not provide the same benefit in women. Minoxidil, a vasodilator initially used as a treatment for high blood pressure, is thought to enhance hair growth via activity at potassium channels and/or prostaglandin levels [2]. Surgical treatments are expensive and invasive and the drugs in current use combine relatively low efficacy with a non-insignificant risk of adverse effects.

Ageratum conyzoides Linn, (A. conyzoides) commonly known as Billy Goat Weed, is a widely available annual herb which belongs to the family Asteraceae, tribe Eupatoriae. It has long-standing medicinal use in the tropical and subtropical regions [5] especially in Africa, Asia and South America where it has been traditionally used for skin disorders, gastrointestinal complaints, headache, rheumatism, pneumonia and wound healing [6]. The plant possesses antimicrobial, antioxidant, anti-inflammatory and analgesic pharmacological activities and has allelopathic properties useful in horticulture [6].

The plant has known toxic effects due to low but measurable levels of pyrrolizidine alkaloids [7]. An alkaloid-free A. conyzoides extract showed no adverse effects in vitro and in vivo acute and semi-acute models, or in a 90-day repeated-dose oral toxicity study [8]. The same alkaloid-free extract was devoid of fetotoxic and teratological toxicity in a prenatal developmental toxicological study in rats [9].

Constituents within A. conyzoides inhibit 5-alpha-reductase gene expression and were therefore considered likely to reduce dihydrotestosterone production [10]. In recently published open-label and in vitro studies, daily topical A. conyzoides application for a period of 8 weeks was confirmed to inhibit 5α-reductase, reduce levels of PGD2 and act as an effective and safe treatment option for hair loss in men and in women [11].

Methodology

The study was a double-blind, randomised, clinical trial with 12-week treatment duration. It was conducted by RDC Clinical between September 2020 and March 2022 in Queensland, Australia in compliance with the International Conference on Harmonization (ICH) Guideline for Good Clinical Practice (GCP).

80 healthy males and females over 18 years of age with self-reporting hair loss were enrolled in this study. Exclusion criteria included history of clinically significant medical conditions including, but not limited to, cardiovascular, neurological, psychiatric, renal, immunological, endocrine (including uncontrolled diabetes or thyroid disease) or haematological abnormalities that are uncontrolled. Scalp conditions or any other genetic disease or issue that could contribute to baldness, current use of hair growth formulations, history of radiotherapy to scalp for cancer treatment, current or past history of cicatricial alopecia, participation in another hair growth trial 3 months before the start of this study, alternation in hair style, extreme hair types (e.g., dreadlocks, afro), colouring, bleaching, straightening or curling. Females with clinical diagnosis of menstrual and/or endocrine disorders, PCOS, hyperandrogenism, pregnant, up to 12 months postpartum or lactating, or not on a suitable form of birth control (i.e., oral contraceptive pill) were excluded. Males who have used or continue to use antihypertensive, steroids, spironolactone, ketoconazole, cytotoxic compounds, anticonvulsant drugs, oestrogens or progesterone within the last six months were also excluded.

Participants were randomized into two groups: A. conyzoides topical gel 0.5% strength (supplied by Gencor Pacific Ltd) and topical gel placebo. They were required to apply 2 teaspoons of gel onto the scalp twice a day (morning and evening) for the duration of the study. Participants were required to attend the study site for hair density assessment tests, hair tug & pull test and blood tests for measurement of blood serum markers (DHT, IGF-1, HDL, Erdr1, PTGDS, PGDT, GPR44, FBC, E/LFT, TSH, ferritin and Vitamin D). Quality of life, diet and improvement in hair were recorded through self-reported questionnaires.

Change in hair growth over a 12-week period was determined by measurement of hair density using the Hair Check instrument. Other assessments included the Norwood/Hamilton scale (for males) and Ludwig Savin scale (for females) and photographs of affected scalp regions.

Decrease in hair loss over a 12-week period was measured by the mean number of hairs lost during a one minute combing test. In this test >150 hairs was graded as ‘poor’, 100-150 hairs was graded ‘fair’ and 50-100 hairs was graded ‘good’. Hair tug or pull test and photographs of affected regions of the scalp were also used to measure the decrease in hair loss. Change in hair color over a 12-week period was determined by comparing photographs of the scalp at baseline and at 12 weeks. Participants monitored hair quality evaluation and quality of life impact using self-assessment questionnaires.

Statistical analysis

ANOVA and t-tests or Mann-Whitney test were conducted to compare change from baseline to 12 weeks data where statistical significance was defined as p<0.05.

Results

80 participants enrolled in the study. 15 dropped out or were lost to follow-up. Participants who completed at least week 4 were included as intention to treat; one participant was excluded as an outlier as their baseline measures were over 3 times SD. Data for 67 participants are presented below.

Baseline demographics

There were no statistical differences between groups at baseline or week 4, 8 or 12 for any of the demographic or anthropometric measures above (Table 1).

Hair density (as measured by Hair check device)

The hair mass index is a measure of hair density in an area of the scalp. The hair mass measured in the thinning area is calculated against an area of control hair (not thinning) to generate the hair loss ratio.

The hair density significantly increased from baseline in the A. conyzoides group from week 8 and the change was significantly different between groups at week 12.

The hair loss ratio was also significantly different from baseline in the Ageratum group at week 8 and 12 and there was a significant difference between groups at week 12 (Table 2).

Other hair measures

No significant differences were seen in either group from baseline or between groups for hair fall (comb test), the hair pull test or the Hamilton-Norwood and Savin hair scales (Table 3).

The hair fall (comb) test measures the number of hairs lost. The hairline measure is from the eyebrow to first hair growth at hairline (cm) (Figure 1).

Quality of life

No differences were seen between groups for the quality-of-life questionnaires.

Biochemical and haematological analysis

No significant differences were observed between groups either at baseline or at week 12. All measured blood serum markers remained within the normal physiological levels (Table 4).

Discussion

The results of this double-blind, randomised, placebo-controlled clinical trial confirmed the results of an earlier pilot study [11]. It demonstrated that a topical A. conyzoides formulation increased hair growth in males and females over a period of 12 weeks. There was a significant increase in hair density in affected areas in participants who applied a 0.5% strength A. conyzoides topical gel twice daily when compared to both baseline hair density levels and participants who applied a placebo gel twice daily for 12 weeks. Significant changes in hair density from baseline levels in the A. conyzoides group were seen as early as 8 weeks, while the placebo group showed no difference from baseline at any time-point. Hair growth was assessed by the use of HairCheck®, a sensitive and validated tool which measures hair mass by cross-section trichometry [12].

Hair density scores were used to determine the Hair Loss Ratio (HLR), which compares the hair in the affected area to an area of control (not thinning) hair. The HLR is a measure of hair growth in an affected area. A. conyzoides treatment significantly decreased the HLR between baseline and week 12 and the HLR was significantly lower in the A. conyzoides group compared to the placebo group. Representative photographs show observable increases in hair mass in areas of thinning, at week 12 compared to baseline.

There were no significant differences seen in either group from baseline or between active and placebo groups for hair fall, as assessed by a one-minute combing test, a hair pull test and assessment by the Hamilton-Norwood and Savin hair loss scales. No differences were seen between groups for participant’s quality of life. Assessed biochemical and haematological remained within normal parameters in both groups, with no significant changes between groups either at baseline or the end of the study.

Ageratum conyzoides is believed to improve symptoms of hair loss through inhibition of 5α-reductase and reduction of prostglandin PGD2, both of which are implicated in androgenetic alopecia (AGA) [1-3,13]. While 5α-reductase converts testosterone to the potent AGA-causing androgen Dihydrotestosterone (DHT) [1,14,15], PGD2, has been linked to hair growth inhibition through G-protein-coupled receptor 44 (GPCR 44) signalling [2,3,13] and up-regulation of pro-inflammatory mediators [16]. DHT and PGD2 are elevated in the balding scalp and correlate with reduced hair growth [2,3,17].

Previously, we demonstrated that an A. conyzoides extract dose-dependently inhibited 5α-reductase gene expression and PGD2, release, in human hair dermal papilla cells [11]. These are in line with other in vitro studies, which have shown A. conyzoides inhibition of PGD2 precursor, prostaglandin D synthase (PGDS) and 5α-reductase mRNA expression [10,18]. The absence of change in serum testosterone and DHT in this study reflects basic pharmacokinetics; the topical application of small amounts of A. conyzoides extract would not be expected to exert systemic effects and their absence here can be regarded as a secondary safety indication.

Our open-label pilot study on 28 adult males and females exhibiting pattern baldness documented an improvement in temporal recession in men, self-reported hair loss symptoms and quality of life in men and women after applying 0.5% or 1% strength A. conyzoides topical gel formulation twice daily over 8 weeks.

The pilot study was limited by its open-label design, lack of placebo control, small sample size and low number of female participants. Our current clinical trial has a more robust design with a greater number of participants. Female participants were still considerably less than a male, which reflects the increased prevalence of hair loss among males.

Compared to Finasteride and Minoxidil, A. conyzoides has a good safety and tolerability profile [1,10,13,19]. The lack of adverse effects in vitro and in pre-clinical toxicology testing is consistent with our previous pilot study [11] and the current clinical study, in which the product was well tolerated by the participants. We conclude that A. conyzoides topical gel formulation is a safe and effective treatment for enhancing hair growth in adults.

Conclusion

The results of the present study demonstrate the safety and efficacy of a short-term topical A. conyzoides application in both men and women. While no significant changes were reported in overall hair loss, there was a clear improvement in hair growth in affected areas, indicating net hair growth due to application of A. conyzoides.

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