How It Works
Bottom Line: Forskolin has not been shown to be an effective cancer therapy in human. More large scale clinical studies are needed to support its other uses.
Forskolin is a root extract of the Indian plant Coleus forskohlii. It is thought to stimulate a cell enzyme called adenylate cyclase, causing higher-than-normal levels of cAMP, a molecule that is responsible for many cellular effects. Some of these effects include the breakdown of fats, dilation of blood vessels and airways, inhibition of blood clotting, and improve of the heart's function. Recent animal study showed that forskolin can cause tanning when applied directly to the skin without exposure to the sun. It has been proposed to be used in sunless tanning lotion to reduce skin cancer risks. Although these effects have been studied in the laboratory setting, very few clinical trials have been performed to test whether these effects also occur in humans. In a number of studies, forskolin was found to lower pressure in the eye but this effect remains controversial.
Purported Uses
As a bronchodilator to treat asthma
Forskolin may cause cellular changes that stimulate the dilation of airways.
To treat cancer
Scientific evidence is limited to lab and animals studies. There is no human trial to support this use.
To increase cardiac output in congestive heart failure
Two clinical trials found positive effects of intravenous forskolin extract in patients with acute heart failure, but overall support for this use is not strong. Oral forms of this herb have not been tested in humans.
As an eye drop, to reduce intra-ocular pressure in glaucoma
Studies in humans have conflicting results.
To lower high blood pressure
Forskolin is known to cause cellular changes that lead to blood vessel dilation, which should lower blood pressure, but there is no proof from clinical trials that this effect occurs in humans.
For weight loss
A small clinical study suggests forskolin may have benefits in obese men.
For tanning
This has been studied in animals. More studies are needed in humans.
Research Evidence
Heart failure:
Two clinical trials conducted in Japan used an intravenous forskolin extract to treat patients with acute heart failure, with positive results, but overall there is no strong support for this use. In addition, it is not known whether forskolin taken by mouth will have the same effect as when it is given intravenously.
Warnings
- Forskolin formulations that are not designed for use in the eye (such as topical creams or extracts meant to be taken by mouth) SHOULD NOT BE PLACED DIRECTLY IN THE EYE.
- This product is regulated by the FDA as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. The product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
- Acute poisoning after the consumption of Coleus forskolii products, possibly from contaminants, have been reported in Europe
Do Not Take If
You are taking medication for high blood pressure such as beta-blockers, vasodilators, ACE inhibitors, or calcium channel blockers (Forskolin may lower your blood pressure even more).
You are taking warfarin or other blood thinners (Forskolin may have additive effects, increasing the risk of bleeding or bruising).
Side Effects
Low blood pressure
Slow heart rate
Special Point
Although forskolin is used to reduce intra-ocular pressure in glaucoma, no sterile eye drop formulation is available.
The intravenous form of forskolin is not available in the United States.
Scientific Name
Coleus forskohlii
Common Name
Makandi, colforsin
Clinical Summary
Forskolin is a diterpene derived from the root of Coleus forskohlii. It is used for a variety of conditions, including cancer, obesity, glaucoma, asthma, and heart failure. Forskolin was shown in animal studies to promote the activation of adenylate cyclase and increase intracellular concentrations of cyclic adenosine monophosphate(cAMP)
(1). Treatment of uropathogenic E.coli (UPEC)-infected mice with forskolin resulted in reduced number of bacteria via cyclicAMP-regulated exocytosis
(18). Forskolin and derivatives have also been studied for their anticancer effects in vitro
(1) and in animals
(3). However, this has yet to be confirmed in human studies. Small clinical trials did suggest forskolin can benefit obese men in weight management
(4). Forskolin eye drops may reduce intra-ocular pressure
(5) and oral forskolin capsules help reduce asthma attacks
(6). When administered intravenously or inhaled, Forskolin has bronchodilation effect
(7) (8). Other studies demonstrated forskolin to have cardiovascular benefits due to its inotropic
(9), antiinflammatory
(10) and antiplatelet properties
(11). Forskolin, when applied on the skin of mice, can stimulate the production of melanin in the absence of ultraviolet light
(12). It has been proposed for use in sunless tanning lotions to reduce the risk of skin cancer by decreasing exposure to sun. Patients using anticoagulants and antihypertensive medications should use forskolin with caution. Cases of acute poisoning after the consumption of Coleus forskolii products, possibly from contaminants, have been reported in Europe
(13).
Purported uses
Allergies
Asthma
Cancer treatment
Congestive heart failure
Glaucoma
Hypertension
Weight loss
Constituents
Diterpenes: Forskolin
Essential oils
Mechanism of Action
Forskolin activates adenylate cyclase through direct stimulation of enzyme and by modulating enzyme activities. These lead to increase in intracellular concentrations of cyclic adenosine monophosphate(cAMP)
(1). This may explain the bronchodilation
(6) (7) (8), inotropic
(9), vasodilatory
(14) and antiplatelet
(11) effects of Forskolin. Forskolin has also been reported to increase cellular acetylcholinesterase and protect neuronal cells from organophosphate toxicity
(15). Forskolin is thought to reduce body fat and has been studied as a weight loss agent
(4). In vitro and animals studies have shown forskolin and its derivative can induce apoptosis in human gastric cancer cells
(2) and can inhibit melanoma cell-induced platelet aggregation and reduce lung metastasis
(3). Forskolin upregulates the expression of cytochrome P450 3A (CYP3A) family through the pregnane-X-receptor that regulates the
CYP3A genes
(16) (17).
Adverse Reactions
Reported: Hypotension, tachycardia
(1)
Herb-Drug Interactions
Anti-hypertensives: Forskolin may have additive hypotensive effect with beta-blockers, vasodilators, calcium channel blockers, etc.
(9).
Anticoagulants: Forskolin may cause bleeding due to additive platelet inhibition
(11).
Forskolin can induce CYP3A gene expression and can potentially increase the metabolism of drugs that are substrates of related microsomal enzymes
(16) (17).
Literature Summary and Critique
Limited data are available concerning the efficacy of forskolin. Most studies performed with forskolin have been human trials; those performed on heart failure and glaucoma are inconclusive.
(6) (7)
References
- Seamon KB, Padgett W, Daly JW. Forskolin: unique diterpene activator of adenylate cyclase in membranes and in intact cells. Proc Natl Acad Sci U S A, 1981. 78(6):3363-7.
- Li Z, Wang J. A forskolin derivative, FSK88, induces apoptosis in human gastric cancer BGC823 cells through caspase activation involving regulation of Bcl-2 family gene expression, dissipation of mitochondrial membrane potential and cytochrome c release. Cell Biol Int, 2006.
- Agarwal KC, Parks RE, Jr. Forskolin: a potential antimetastatic agent. Int J Cancer, 1983. 32(6):801-4.
- Godard MP, Johnson BA, Richmond SR. Body composition and hormonal adaptations associated with forskolin consumption in overweight and obese men. Obes Res, 2005. 13(8):1335-43.
- Meyer BH, et al. The effects of forskolin eye drops on intra-ocular pressure. S Afr Med J, 1987. 71(9):570-1.
- Gonzalez-Sanchez R, et al. Forskolin versus sodium cromoglycate for prevention of asthma attacks: a single-blinded clinical trial. J Int Med Res, 2006. 34(2):200-7.
- Wajima Z, et al. Intravenous colforsin daropate, a water-soluble forskolin derivative, prevents thiamylal-fentanyl-induced bronchoconstriction in humans. Crit Care Med, 2002. 30(4):820-6.
- Bauer K, et al. Pharmacodynamic effects of inhaled dry powder formulations of fenoterol and colforsin in asthma. Clin Pharmacol Ther, 1993. 53(1):76-83.
- Metzger H, Lindner E. The positive inotropic-acting forskolin, a potent adenylate cyclase activator. Arzneimittelforschung, 1981. 31(8):1248-50.
- Hayashida N, et al. Antiinflammatory effects of colforsin daropate hydrochloride, a novel water-soluble forskolin derivative. Ann Thorac Surg, 2001. 71(6):1931-8.
- Christenson JT, Thulesius O, Nazzal MM. The effect of forskolin on blood flow, platelet metabolism, aggregation and ATP release. Vasa, 1995. 24(1):56-61.
- D'Orazio JA, et al. Topical drug rescue strategy and skin protection based on the role of Mc1r in UV-induced tanning. Nature, 2006. 443(7109):340-4.
- Daykin A. Acute Poisoning From Coleus Forskohlii Containing Products, Letter to Herbalists, UK. 2005. (Accessed on March 18, 2009)
- Baumann G, et al. Cardiovascular effects of forskolin (HL 362) in patients with idiopathic congestive cardiomyopathy--a comparative study with dobutamine and sodium nitroprusside. J Cardiovasc Pharmacol, 1990. 16(1):93-100.
- Curtin BF, et al. Forskolin, an inducer of cAMP, up-regulates acetylcholinesterase expression and protects against organophosphate exposure in neuro 2A cells. Mol Cell Biochem, 2006.
- Dowless MS, et al. Cyclic AMP-independent activation of CYP3A4 gene expression by forskolin. Eur J Pharmacol, 2005. 512(1):9-13.
- Ding X, Staudinger JL. Induction of drug metabolism by forskolin: the role of the pregnane X receptor and the protein kinase a signal transduction pathway. J Pharmacol Exp Ther, 2005. 312(2):849-56.
- Bishop BL, Duncan MJ, Song J, et al. Cyclic AMP-regulated exocytosis of Escherichia coli from infected bladder epithelial cells. Nat Med. 2007.
