Coleus forskohlii

Alternative Medicine Review, March, 2006

In a randomized, double-blind, placebo-controlled, cross-over trial with two separate arms, 10 healthy, non-smoking men were given a forskolin (1%) suspension in one eye and placebo in the other eye; proxymetacaine (0.5%) was the local anesthetic. The forskolin suspension resulted in decreases in IOP, but the differences between the forskolin treatment and placebo treatment at eight hours post application were statistically insignificant. Six men participated in a second arm of the study and a different local anesthetic (0.4% oxybuprocaine) was used. In this study arm a highly significant 25-percent reduction of IOP was observed at six hours post application. The different results in the two arms may be attributable to the different topical anesthetics used prior to forskolin application. (26) These results suggest forskolin may be of benefit in reducing IOP in glaucoma patients.

Cancer Metastases

Many metastasizing tumor cell lines induce platelet aggregation both in vitro and in vivo. Upon aggregation, platelets release substances that promote tumor growth. (27) Researchers have demonstrated forskolin's ability to block platelet aggregation via its stimulation of platelet adenylate cyclase and increase of intracellular cAME (22) Agarwal and Parks gave 82 [micro]g forskolin to mice 30-60 minutes prior to injection with a highly metastatic melanoma cell line (B16 F10). Forskolin reduced tumor colonization in the lungs by 70 percent. (28)

Obesity and Weight Loss

In vitro and animal studies demonstrate lipolysis in fat cells is stimulated by forskolin (17,29,30) via activation of adenylate cyclase and increased levels of cAME In a study involving 34 women, researchers discovered adipocytes from morbidly obese women have decreased adenylate cyclase activity, compared to adipocytes from normal weight women. (31) In a small study, six overweight women were given 250 mg Coleusforskohlii, standardized to contain 10-percent forskolin, twice daily for eight weeks. Average weight loss at the end of the trial was 10 pounds, with an eight-percent reduction in body fat. Blood pressure tended to be lower in all women during the trial. No adverse effects were reported, indicating Coleus forskohlii might be safe and effective for losing weight and body fat. (32) More research with a larger study population is indicated.

Other Clinical Indications

Research has shown forskolin stimulates thyroid hormone release and increases thyroid hormone production. (15,16) Forskolin has been shown to stimulate digestive secretions, including hydrochloric acid, pepsin, amylase, and pancreatic enzymes, (4,7) suggesting clinical benefit in digestive disorders and malabsorption. Animal research indicates forskolin exerts an antidepressant action via activation of cAME (33) In vitro research indicates forskolin has potent immune-stimulating properties. (34, 35)

Drug/Botanical Interactions

Because forskolin has an inhibitory effect on platelet aggregation, it should be avoided or used with caution in conjunction with anticoagulant medications. (22) Caution should be used when giving forskolin with antihypertensive agents as it may have a potentiating effect on these drugs. (9)