Mirabegron

Oral
Overactive bladder
Adult: For the symptomatic treatment of urinary frequency, urgency, and/or urge urinary incontinence: As extended-release or prolonged-release tab: Initially, 25 mg once daily, may be increased to 50 mg once daily after 4-8 weeks according to patient's response and tolerability. Dosage and treatment recommendations may vary among individual products or between countries (refer to specific product or local guidelines).
Renal impairment: ESRD (eGFR <15 mL/min/1.73 m²) or patient on haemodialysis: Not recommended. eGFR 15-29 mL/min/1.73 m²: Do not exceed 25 mg once daily.
Hepatic impairment: Moderate (Child-Pugh class B): Do not exceed 25 mg once daily. Severe (Child-Pugh class C): Not recommended.

Special Populations: Patients with renal impairment who are concurrently taking strong CYP3A inhibitors (e.g. ketoconazole, itraconazole, ritonavir, clarithromycin): Severe (eGFR 15-29 mL/min/1.73 m²): Not recommended. Mild to moderate (eGFR 30-89 mL/min/1.73 m²): Reduce dose to 25 mg once daily. Patients with hepatic impairment who are concurrently taking strong CYP3A inhibitors (e.g. ketoconazole, itraconazole, ritonavir, clarithromycin): Mild (Child-Pugh class A): Reduce dose to 25 mg once daily. Moderate (Child-Pugh class B): Not recommended.

XR tab: May be taken with or without food. Swallow whole, do not chew/crush/divide.

Severe uncontrolled hypertension (systolic blood pressure ≥180 mmHg and/or diastolic blood pressure ≥110 mmHg).

Patient with controlled and less severe hypertension, history of QT prolongation, clinically significant bladder outlet obstruction, benign prostatic hyperplasia, history of post-void residual (PVR) volume >200 mL. Patients receiving antimuscarinic agents to treat overactive bladder or drugs known to prolong QT interval. Patients with renal or hepatic impairment concurrently taking strong CYP3A inhibitors. Renal and hepatic impairment. Children. Pregnancy and lactation. Patient Counselling Women of childbearing potential should use effective contraception during treatment. Monitoring Parameters Monitor blood pressure at baseline and periodically during treatment; PVR at baseline and when clinically indicated. Assess for signs and symptoms of urinary retention.

Significant: CV effects (e.g. hypertension, tachycardia, palpitation); urinary retention, particularly in patients with bladder outlet obstruction. Cardiac disorders: Atrial fibrillation. Gastrointestinal disorders: Nausea, constipation, diarrhoea, dry mouth, dyspepsia, gastritis. Investigations: Increased GGT, AST, and ALT. Musculoskeletal and connective tissue disorders: Joint swelling, back pain. Nervous system disorders: Headache, dizziness. Psychiatric disorders: Insomnia, confusion. Renal and urinary disorders: UTI, cystitis. Reproductive system and breast disorders: Vaginal infection, vulvovaginal pruritus. Respiratory, thoracic and mediastinal disorders: Nasopharyngitis, sinusitis. Skin and subcutaneous tissue disorders: Urticaria, macular or papular rash, pruritus.
Potentially Fatal: Angioedema involving the face, lips, tongue and/or larynx.

Symptoms: Increased pulse rate and systolic blood pressure. Management: Symptomatic and supportive treatment. Monitor pulse rate, blood pressure and ECG.

Increased exposure with strong CYP3A inhibitors (e.g. ketoconazole, itraconazole, ritonavir, clarithromycin). Decreased serum concentration with CYP3A or P-gp inducers. May increase the serum concentration and exposure of CYP2D6 substrates (e.g. metoprolol, thioridazine, desipramine, imipramine, flecainide, propafenone), P-gp substrates (e.g. digoxin, dabigatran), and warfarin. Increased risk of urinary retention with antimuscarinic agents (e.g. solifenacin, tolterodine, darifenacin).

Mirabegron is a potent and selective β₃-adrenergic receptor agonist. It activates β₃-adrenergic receptors in the bladder which results in the relaxation of detrusor smooth muscles during urine storage phase, thus increasing bladder capacity.
Onset: Overactive bladder: Within 8 weeks.
Absorption: Absolute bioavailability: 29-35%. Time to peak plasma concentration: Approx 3-5 hours (extended-release tab).
Distribution: Widely distributed in the body. Plasma protein binding: Approx 71%, mainly to albumin and α₁-acid glycoprotein.
Metabolism: Extensively metabolised via multiple pathways including dealkylation, oxidation glucuronidation, and amide hydrolysis by multiple enzymes (involving UGT, butyrylcholinesterase, CYP3A4, CYP2D6, and possibly alcohol dehydrogenase) into 2 major inactive metabolites.
Excretion: Via urine (55%; approx 25% as unchanged drug); faeces (34%). Terminal elimination half-life: Approx 50 hours.

Oral: Extended-release or prolonged-release tab: Store between 15-30°C.

Drugs for Bladder & Prostate Disorders

G04BD12 - mirabegron ; Belongs to the class of urinary antispasmodics.