Bumetanide


Bumetanide, sold under the trade name Bumex among others, is a medication used to treat swelling and high blood pressure. This includes swelling as a result of heart failure, liver failure, or kidney problems. It may work for swelling when other medications have not. For high blood pressure it is not a preferred treatment. It is taken by mouth, or by injection into a vein or muscle. Effects generally begin within an hour and lasts for about six hours.
Common side effects include dizziness, low blood pressure, low blood potassium, muscle cramps, and kidney problems. Other serious side effects may include hearing loss and low blood platelets. People with a sulfa allergy, may also be allergic to bumetanide. Blood tests are recommended regularly for those on treatment. Safety during pregnancy and breastfeeding is unclear. Bumetanide is a loop diuretic and works by decreasing the reabsorption of sodium by the kidneys.
Bumetanide was patented in 1968 and came into medical use in 1972. It is available as a generic medication. A month supply in the United Kingdom costs the NHS about £1.20 as of 2019. In the United States the wholesale cost of this amount is about US$12. In 2017, it was the 277th most commonly prescribed medication in the United States, with more than one million prescriptions.

Uses

Medical uses

It used to treat swelling and high blood pressure. This include swelling as a result of heart failure, liver failure, or kidney problems. For high blood pressure it is not a preferred treatment. It is taken by mouth, or by injection into a vein or muscle.

Other uses

It 2008, ESPN reported that four NFL players were being suspended under the steroid policy as a result of taking bumetanide. It is sometimes used for weight loss because, as a diuretic, it removes water, but it also masks other drugs, including steroids, by diluting the contents of the user's urine, yielding a lower concentration of filtered substances, which makes them less likely to be detected.
Bumetanide was an undisclosed active ingredient in the over-the-counter weight loss supplement StarCaps, which was removed from the market after its presence was discovered by the United States Food and Drug Administration.

Side effects

Common side effects include dizziness, low blood pressure, low blood potassium, muscle cramps, and kidney problems. Other serious side effects may include hearing loss and low blood platelets. People with a sulfa allergy may also be allergic to bumetanide. Blood tests are recommended regularly for those on treatment. Safety during pregnancy and breastfeeding is unclear.

Mechanism of action

Bumetanide is a loop diuretic and works by decreasing the reabsorption of sodium by the kidneys.
The main difference between bumetanide and furosemide is in their bioavailability and potency. About 60% of furosemide is absorbed in the intestine, and there are substantial inter- and intraindividual differences in bioavailability. About 80% of bumetanide is absorbed, and its absorption does not change when it is taken with food. It is said to be a more predictable diuretic, meaning that the predictable absorption is reflected in a more predictable effect. Bumetanide is 40 times more potent than furosemide for people with normal renal function.

Synthesis

Bumetanide, 3-butylamino-4-phenoxy-5-sulfamoylbenzoic acid, is synthesized from 4-chlorobenzoic acid. In the first stage of synthesis, it undergoes sulfonylchlorination by chlorosulfonic acid, forming 4-chloro-3-chlorosulfonylbenzoic acid, which is further nitrated with nitric acid to 4-chloro-3-chlorosulfonyl-5-nitrobenzoic acid. Reacting this with ammonia gives 5-aminosulfonyl-4-chloro-3-nitrobenzoic acid, which when reacted with sodium phenolate is transformed into 5-amino-sulfonyl-3-nitro-5-phenoxybenzoid acid. Reduction of the nitro group in this product by hydrogen using a palladium on carbon catalyst gives 3-amino-5-aminosulfonyl- 5-phenoxybenzoic acid. Finally, reacting this with butyl alcohol in the presence of sulfuric acid gives the desired bumetanide.

Research

In the brain, bumetanide blocks the NKCC1 cation-chloride co-transporter, and thus decreases internal chloride concentration in neurons. In turn, this concentration change makes the action of GABA more hyperpolarizing, which may be useful for treatment of neonatal seizures, which quite often are not responsive to traditional GABA-targeted treatment, such as barbiturates. Bumetanide is therefore under evaluation as a prospective antiepileptic drug.