Mirabegron

Question 1

What are the contraindications of mirabegron ?

Answer 1

• Severe uncontrolled hypertension (systolic blood pressure 180 mmHg or higher, or diastolic blood pressure 110 mmHg or higher).
• Severe hepatic impairment.
• End stage renal disease.

Question 2

Usually the dose of mirabegron is 50 mg OD to start with, but if a patient has moderate hepatic impairment, what dose should be given ?

Answer 2

• start with 25 mg OD
• However you would need to avoid if the person is also taking a potent CYP3A4 inhibitor, clarithromycin, itraconazole, or ritonavir- as increase plasma conc of mirabegron

Question 3

If mirabegron is taken with the following drugs, what would happen ?
Beta blockers (metoprolol).
Colchicine.
Dabigatran.
Digoxin. 
Everolimus, sirolimus.
Fexofenadine.
Loperamide. 
Tricyclic antidepressants (for example imipramine).

Answer 3

increase the levels of these drugs: caution

Question 4

What are the cautions for mirabegron ?

Answer 4

History of QT-interval prolongation;

stage 2 hypertension

Question 5

What are common/very common s/e of mirabegron ?

Answer 5

Common adverse effects include:
Urinary tract infection.
Headache, dizziness.
Tachycardia (arrhythmias)
Nausea, constipation, diarrhoea

Question 6

What are the monitoring requirements for mirabegron ?

Answer 6

Blood pressure should be monitored before starting treatment and regularly during treatment, especially in patients with pre-existing hypertension.

Question 7

How does Betmiga work?

Answer 7

The active substance in Betmiga, mirabegron, is a beta-3-adrenergic-receptor agonist. It works by attaching to and activating beta-3 receptors that are found in the muscle cells of the bladder. Experimental studies have shown that, when activated, beta-3 receptors cause the bladder muscles to relax. This is thought to lead to an increase in the capacity of the bladder and changes in the way the bladder contracts, resulting in fewer bladder contractions and thus fewer unwanted urinations.