Mirago Prescribing Guide

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name: mirago-prescribing-guide
description: Complete bedside prescribing reference for Mirago (mirabegron, beta-3 adrenoceptor agonist) for overactive bladder — covering contraindications, safety screening, drug interactions, dose selection in special populations, titration, and administration. Use when a clinician asks how to start mirabegron, what dose to use in renal or hepatic impairment, is mirabegron safe in this patient, mirabegron drug interactions, or Mirago for OAB.
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# Mirago (mirabegron) — Complete Prescribing Guide

**Indian brand:** Mirago | **Drug class:** Selective beta-3 adrenoceptor agonist  
**Available strengths:** 25 mg, 50 mg extended-release tablets (once daily)

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## STEP 1 — Confirm Indication

**Indicated for:** Overactive bladder (OAB) in adults with:
- Urgency
- Urgency urinary incontinence
- Urinary frequency

**Not established in:** Pediatrics (<18 years)  
**Geriatrics (≥65 years):** Safe to use — no dose adjustment needed

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## STEP 2 — Contraindications (Hard Stop)

Do NOT prescribe if ANY of these apply:

| Condition | Threshold |
|---|---|
| Severe uncontrolled hypertension | SBP ≥180 mmHg **and/or** DBP ≥110 mmHg |
| Pregnancy | Any trimester |
| Hypersensitivity to mirabegron | Any ingredient in the formulation |

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## STEP 3 — Safety Warnings (Proceed with Caution)

Work through each before prescribing:

**Cardiovascular**
- **Hypertension (controlled):** Check BP at baseline and periodically. Mirago raises BP ~0.5–1 mmHg in OAB patients; up to 4/3.7 mmHg in healthy volunteers at 50 mg.
- **QTc prolongation risk:** Mirago causes dose-dependent QTc prolongation (<5 ms at 50 mg — therapeutic dose). Use with caution if: known QT prolongation history, hypokalemia, or concurrent QTc-prolonging drugs.
- **Tachyarrhythmia / ischemic heart disease:** Mirago increases HR by ~1 bpm (OAB patients at 50 mg); up to 8.5 bpm in healthy female volunteers. Use caution.

**Genitourinary**
- **Bladder outlet obstruction (BOO):** Urinary retention reported post-marketing, especially with concurrent antimuscarinics. Use with caution.

**Immune**
- **Angioedema** (face, lips, tongue, larynx): Rare but life-threatening. Discontinue immediately; secure airway if upper airway involved.

**Ophthalmological**
- **Glaucoma:** Monitor IOP regularly during treatment (though 100 mg did not increase IOP in phase 1 studies).

**Nursing mothers:** Avoid — excreted in rodent milk; no human data.

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## STEP 4 — Drug Interaction Check

Run through this table for every patient:

| Co-medication | Mechanism | Action Required |
|---|---|---|
| **Flecainide, propafenone** (narrow TI CYP2D6 substrates) | Mirago ↑ their exposure substantially | **Cap Mirago at 25 mg/day. Do not escalate.** |
| **Metoprolol, desipramine** (CYP2D6 substrates, wider TI) | Mirago ↑ Cmax by ~79–90% | Caution; monitor for β-blocker/TCA side effects |
| **Digoxin** | Mirago weak P-gp inhibitor: ↑ digoxin Cmax 29%, AUC 27% | Start digoxin at lowest dose; titrate by serum levels |
| **Antimuscarinics for OAB** (solifenacin, oxybutynin, etc.) | Additive urinary retention risk in BOO | Caution in BOO; watch for retention |
| **QTc-prolonging drugs** (see list below) | Additive QTc risk | Avoid combination if patient has QT risk factors |
| **Warfarin** | Minor ↑ in warfarin Cmax/AUC (~4–9%); no INR effect on single dose | Monitor INR; long-term interaction not fully studied |
| Metformin, solifenacin, tamsulosin, ketoconazole, rifampicin | No clinically significant PK interaction | No dose adjustment needed |

**QTc-prolonging drugs to flag:**
Class IA/IC/III antiarrhythmics · Antipsychotics (haloperidol, chlorpromazine, ziprasidone) · TCAs (amitriptyline, imipramine) · Macrolides (erythromycin, clarithromycin) · Quinolones (moxifloxacin, levofloxacin) · Azole antifungals · Antimalarials (chloroquine, quinine) · Methadone · Domperidone · 5-HT3 antagonists (ondansetron) · SSRIs/SNRIs (fluoxetine, citalopram, venlafaxine)

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## STEP 5 — Dose Selection by Patient Profile

| Patient | Starting Dose | Maximum Dose |
|---|---|---|
| Standard adult | 25 mg OD | 50 mg OD |
| Elderly ≥65 years | 25 mg OD | 50 mg OD (no adjustment) |
| Mild renal impairment (CrCl/eGFR 30–89 mL/min) | 25 mg OD | 50 mg OD |
| **Severe renal impairment (CrCl/eGFR 15–29 mL/min)** | 25 mg OD | **25 mg OD — do not escalate** |
| **ESRD (CrCl/eGFR <15, or on dialysis)** | **NOT RECOMMENDED** | — |
| Mild hepatic impairment (Child-Pugh A) | 25 mg OD | 50 mg OD |
| **Moderate hepatic impairment (Child-Pugh B)** | 25 mg OD | **25 mg OD — do not escalate** |
| **Severe hepatic impairment (Child-Pugh C)** | **NOT RECOMMENDED** | — |
| **With flecainide or propafenone** | 25 mg OD | **25 mg OD — do not escalate** |

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## STEP 6 — Titration and Administration

- **Start:** 25 mg once daily, with or without food
- **Assess response:** At 8 weeks (effective within 8 weeks at 25 mg)
- **Escalate to 50 mg:** If inadequate response and well-tolerated; once daily
- **Do not exceed 50 mg/day** (supra-proportional bioavailability increases above this dose)
- **Administration:** Swallow whole with water — do NOT crush, chew, or divide tablet
- **Missed dose:** Take next scheduled dose as usual — never double-dose

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## STEP 7 — Clinical Guardrails

- **Urine dipstick protein:** Mirago may cause false-positive results. Always confirm with quantitative protein assay if dipstick is positive.
- **Liver enzymes:** ALT/AST rose >10-fold in 0.3% of patients on 50 mg in long-term studies (subsequently normalised). Monitor if hepatic symptoms develop.
- **Angioedema:** Can occur after first dose or after multiple doses. If tongue, hypopharynx, or larynx involved — STOP immediately, manage airway.
- **Stevens-Johnson syndrome:** Rare (single case report at 100 mg). Discontinue if severe skin reaction develops.
- **Do not use in pregnancy** — embryo-fetal toxicity in animals (wavy rib, cardiomegaly, reduced fetal weight).
- **Neoplasm signal:** 1.3% at 100 mg (long-term study) vs 0.1% at 50 mg and 0.5% active control — unclear significance; not a reason to avoid at therapeutic dose (50 mg), but worth noting in long-term users.

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**Source:** Myrbetriq (mirabegron) Canadian Product Monograph, Astellas Pharma Canada, June 2016. Submission No: 192447. Indian brand equivalent: Mirago (mirabegron).