Mirabegron

September 10, 2018
I can minimize your need to go to the bathroom during the night.
What molecule am I?

Mirabegron, a compound with multiple functional groups, is the active ingredient of drugs used for treating an overactive bladder. It is sold under the trade names Myrbetriq and Betmiga, both marketed by Astellas Pharma (Tokyo).

Mirabegron activates the β3 adrenergic receptor in the detrusor muscle of the bladder. Activating the receptor relaxes the muscle, allowing the bladder to accommodate a greater quantity of urine.

The drug, however, is not without adverse side effects. The most common is elevated blood pressure; but there are many others, including dry mouth, susceptibility to colds, and urinary tract infection.

Although mirabegron is taken orally, one of the hazards listed in its safety data sheets (see hazard information box) is oral toxicity. But the medicine is not toxic unless the patient consumes 5–10 times the normally prescribed dosage.

Mirabegron hazard information

GHS classification*: acute toxicity, oral, category 4
H302—Harmful if swallowed Chemical Safety Warning
GHS classification: skin sensitization, category 1
H317—May cause an allergic skin reaction Chemical Safety Warning
GHS classification: serious eye irritation, category 2A
H319—Causes serious eye irritation Chemical Safety Warning
GHS classification: reproductive toxicity, category 2
H361—Suspected of damaging fertility or the unborn child Chemical Safety Warning
GHS classification: specific target organ toxicity, repeated exposure, category 2
H373—Causes damage to organs through prolonged or repeated exposure Chemical Safety Warning
GHS classification: hazardous to the aquatic environment, long-term hazard, category 1
H410—Very toxic to aquatic life with long-lasting effects Chemical Safety Warning

*Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

Mirabegron fast facts

CAS Reg. No.

223673-61-8

Molar mass 396.51 g/mol
Empirical formula C21H24N4O2S
Appearance White to off-white crystals or powder
Melting point

138–140 ºC

Water solubility Insoluble
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