:Coleus forskohlii

Safety:

Caution should be exercised if combining this herb with blood-pressure medications and "blood thinners." Aspirin should not be taken with Coleus forskohlii without first speaking with your physician or pharmacist. Theoretically Coleus forskohlii could potentiate anti-platelet drugs such as aspirin though this has never been documented.

Coleus forskohlii has a supportive effect when combined with certain medications and may reduce the needed dosage of:

• Albuterol (increase bronchodilation effect in vitro)
• Ephedrine and Pseudoephedrine
• Epinephrine (increase bronchodilation effect in vitro)
• Salmeterol (increase bronchodilation effect in vitro)

Animal model studies conducted on forskolin reported an extremely low order of toxicity (1, 2). Coleus forskohlii, a member of the mint (Lamiaceae) family, has a history of safe use as a spice in Asia. Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been specifically and positively established, although no major side effects have been reported.

The acute LD 50 values for forskolin in the mouse and rat models are (105 mg/kg i.p. & 3,100 mg/kg per oral) and (92 mg/kg i.p. & 2,550 mg/kg per oral), respectively (3).

It has been suggested that Coleus forskohlii should theoretically be avoided by patients gastric ulcers or low blood pressure. Coleus forskohlii should be used with caution by those on prescription antiasthmatics and antihypertensives since Coleus forskohlii may potentiate the effects of these prescription drugs, reducing the appropriate drug dosage (2). The addition or substitution of Coleus forskohlii in this way can help reduce the potential for serious side effects from asthma and blood pressure drugs. Forskolin lowers the blood pressure in dogs and cats and also in spontaneously hypertensive and renal hypertensive rats. (4)

The pharmacological properties of coleonol, a diterpene, isolated from Coleus forskohlii were investigated. Large doses of coleonol have a depressant action on the central nervous system. Note, however, that the overall CNS effect of the whole herb is mood elevation. (5)

Dosage:

Typical dosage recommendations are in the range of 100-300mg/day of a Coleus forskohlii extract (10-20% forskolin), taken in 2-3 divided doses (raw root powders may have only 0.2%-0.3% forskolin).

Eyedrops are 1% forskolin with the generic name Colforsin.

Mechanism:

Forskolin stimulates adenylate cyclase activity, increasing cellular levels of cyclic Adenosine Mono-Phosphate (cAMP), an intermediate communication molecule for many hormones, stimulating hundreds of cellular enzymes.

Effects:

Promotes weight loss and fat loss
Increases lean body mass (muscle)
Improves emotional outlook, elevates mood
Reduces allergies, asthma (anti-histamine effect)
Lowers blood pressure
Relaxes muscles: muscle cramps, stomach cramps, menstrual cramps
Lowers intraocular pressure

Active compound:

Forskolin is a diterpene found in coleus that inhibits the enzyme adenylate cyclase. 7 Adenylate cyclase regulates formation of cAMP, a compound that in turn exerts control over numerous activities in every cell. Forskolin-induced elevation of cAMP levels in cells leads to blood vessel dilation, 8 inhibition of mast cells (and hence reduction in allergic inflammation), 9 increase in thyroid hormone secretion, 10 and stimulation of fat release from fat cells. 11 Forskolin has other properties as well, including inhibition of the pro-inflammatory substance known as platelet-activating factor (PAF) 12 and inhibition of the spread of cancer cells. 13

Much of the research into the actions of forskolin has primarily been completed in an attempt to understand how cAMP is involved in various disease processes. As a result, there has been little human study of the medicinal properties of Coleus forskohlii. Studies in healthy humans, including at least one double-blind study, have repeatedly shown that direct application of forskolin to the eyes lowers pressure in them. 14, 15 Elevated eye pressure can lead to glaucoma.

One non-randomized study on humans has shown that forskolin can reduce blood pressure and improve heart function in people with cardiomyopathy. 16 Forskolin was given by injection in this study; it is unknown if oral coleus extracts would have the same effect. A small double-blind study found that inhaled forskolin could decrease lung spasms in asthmatics compared to placebo. 17

References:

1. Murray, M.T. (1995) The unique pharmacology of Coleus forskohlii . Health Counselor 7(2): 33-35.
2. American Botanical Council. Coleus Forskohlii Monograph. HerbClip May 1, 1997.
3. Agarwal, K.C. and Parks, R.E. (1983) Forskolin: A potential antimetastatic agent. Int. J. Cancer 32: 801-804.
4. Arzneimittelforschung 1978;28(2):284-9 -- Positive inotropic and blood pressure lowering activity of a diterpene derivative isolated from Coleus forskohli: Forskolin. - Lindner E, Dohadwalla AN, Bhattacharya BK.
5. J Ethnopharmacol 1981 Jan;3(1):1-13 -Pharmacological studies on coleonol, a hypotensive diterpene from Coleus forskohlii. - Dubey MP, Srimal RC, Nityanand S, Dhawan BN.
6. Dubey MP, Srimal RC, Nityanand S, Dhawan BN. Pharmacological studies on coleonol, a hypotensive diterpene from Coleus forskohlii. J Ethnopharmacol 1981;3:1–13.
7. Seamon KB, Daly JW. Forskolin: A unique diterpene activator of cAMP-generating systems. J Cyclic Nucleotide Res 1981;7:201–24 [review].
8. Wysham DG, Brotherton AF, Heistad DD. Effects of forskolin on cerebral blood flow: Implications for the role of adenylate cyclase. Stroke 1986;17:1299–303.
9. Marone G, Columbo M, Triggiani M, et al. Forskolin inhibits the release of histamine from human basophils and mast cells. Agents Actions 1986;18:96–9.
10. Roger PP, Servais P, Dumont JE. Regulation of dog thyroid epithelial cell cycle by forskolin, an adenylate cyclase activator. Exp Cell Res 1990;172:282–92.
11. Okuda H, Morimoto C, Tsujita T. Relationship between cyclic AMP production and lipolysis induced by forskolin in rat fat cells. J Lipid Res 1992;33:225–31.
12. Wong S, Mok W, Phaneuf S, et al. Forskolin inhibits platelet-activating factor binding to platelet receptors independently of adenylyl cyclase activation. Eur J Pharmacol 1993;245:55–61.
13. Agarwal KC, Parks RE. Forskolin: A potential antimetastatic agent. Int J Cancer 1983;32:801–4.
14. Caprioli J, Sears M. Forskolin lowers intraocular pressure in rabbits, monkeys and man. Lancet 1983;i:958–60.
15. Badian M, Dabrowski J, Grigoleit HG, et al. Effect of forskolin eyedrops on intraocular pressure in healthy males. Klin Monatsbl Augenheilkd 1984;185:522–6 [in German].
16. Kramer W, Thormann J, Kindler M, Schlepper M. Effects of forskolin on left ventricular function in dilated cardiomyopathy. Arzneim Forsch 1987;37:364–7.
17. Bauer K, Dietersdorfer F, Sertl K, et al. Pharmacodynamic effects of inhaled dry powder formulations of fenoterol and colforsin in asthma. Clin Pharmacol Ther 1993;43:76–83.