Methylhexanamine (also known as methylhexamine, 1,3-dimethylamylamine, 1,3-DMAA, dimethylamylamine, and DMAA; trade names Forthane and Geranamine) is an indirect sympathomimetic drug invented and developed by Eli Lilly and Company and marketed as an inhaled nasal decongestant from 1948 until it was voluntarily withdrawn from the market in the 1980s. Since 2006 methylhexanamine has been sold extensively under many names as a stimulant or energy-boosting dietary supplement under the claim that it is similar to certain compounds found in geraniums, but its safety has been questioned as a number of adverse events and at least five deaths have been associated with methylhexanamine-containing supplements. It is banned by many sports authorities and governmental agencies. Despite multiple warning letters from the FDA, as of 2019, the stimulant remains available in sports and weight loss supplements in the US.
History In April 1944, Eli Lilly and Company introduced methylhexanamine under the brand name Forthane as an inhaled nasal decongestant; Lilly voluntarily withdrew methylhexanamine from the market in 1983. The compound is an aliphatic amine; the pharmaceutical industry had a strong interest in compounds in this class as nasal decongestants in the early 20th century, which led to methylhexanamine and four other similar compounds being brought to market for that use: tuaminoheptane, octin (isometheptene), oenethyl (2-methylaminoheptane), and propylhexedrine; octin and oenethyl were eventually approved for use in keeping blood pressure sufficiently high for patients under anesthesia.
Marketing as dietary supplement Patrick Arnold reintroduced methylhexanamine in 2006 as a dietary supplement, after the final ban of ephedrine in the United States in 2005. Arnold introduced it under the trademarked name Geranamine, a name held by his company, Proviant Technologies. A large number of supplements focusing on fat loss and workout energy (thermogenic or general-purpose stimulants) used the ingredient in concert with other substances such as caffeine, a combination similar to the combination of ephedrine and caffeine. Methylhexanamine-containing supplements sometimes list "geranium oil" or "geranium extract" as a source of methylhexanamine. However, geranium oils do not contain methylhexanamine, and the methylhexanamine in these supplements is added in the form of synthetic material. A variety of studies have explored the possibility that DMAA is found in some types of geraniums, but at present, high quality evidence of DMAA's presence in plants is lacking. Methylhexanamine is synthesized by reacting 4-methylhexan-2-one with hydroxylamine, which converts the 4-methylhexan-2-one to 4-methylhexan-2-one oxime, which is reduced via catalytic hydrogenation; the resulting methylhexanamine can be purified by distillation.
Pharmacology
Methylhexanamine is an indirect sympathomimetic drug that constricts blood vessels and thus has effects on the heart, lungs, and reproductive organs. It also causes bronchodilation, inhibits peristalsis in the intestines, and has diuretic effects. Most studies have been done on pharmacological effects when the drug is inhaled; the understanding of what methylhexanamine does when taken orally are mostly based on extrapolating from the activities of similar compounds. A 2013 review concluded that: "Pharmacological effects after oral intake can be expected on the lungs (bronchodilation) and the nasal mucosa following a single oral dose of about 4–15 mg. Pharmacological effects on the heart can be expected following a single oral dose of about 50–75 mg. Pharmacological effects on the blood pressure can be expected after a single oral dose of about 100 mg. Because of the long half-life, there is a risk that repeated doses within 24–36 hours could lead to steadily stronger pharmacological effects (build-up)." In 2019 and 2023, methylhexanamine was found to show activity consistent with being a norepinephrine and dopamine releasing agent (NDRA).
Detection in body fluids Methylhexanamine may be quantified in blood, plasma, or urine by gas or liquid chromatography-mass spectrometry to confirm a diagnosis of poisoning in hospitalized patients or to provide evidence in a medicolegal death investigation. Blood or plasma methylhexanamine concentrations are expected to be in a range of 10–100 μg/L in persons using the drug recreationally, >100 μg/L in intoxicated patients, and >300 μg/L in victims of acute overdosage.
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