WHAT IS THIS MEDICINE AND
WHAT IS IT USED FOR?
Betmiga contains mirabegron, a medicine
that relaxes the muscle wall of the bladder, allowing it to hold more urine. It
belongs to a new class of bladder medicines called beta-3 adrenergic agonists —
different from older bladder treatments (anticholinergics) and generally with
fewer dry-mouth and constipation side effects. Betmiga is prescribed for
overactive bladder (OAB) — a condition where the bladder contracts too
frequently or suddenly, causing: a sudden strong urge to urinate (urgency),
needing to urinate very often (frequency), and involuntary leakage of urine
(urge incontinence).
3. HOW TO TAKE THIS MEDICINE
Take one 25-50 mg tablet once a day at
the same time each day. Swallow the tablet whole with a glass of water — do not
crush, break, or chew it, as it is a prolonged-release tablet designed to
release slowly. You can take it with or without food. It may take 4–8 weeks to
feel the full benefit of Betmiga.
|
💡
PATIENT TIP: Starting at 25 mg once daily is an option for those who need to
start slowly (e.g., older adults or those on certain medications). Dose
reduction to 25 mg is recommended for patients with severe kidney impairment
combined with certain CYP3A4-inhibiting medicines. Not recommended for severe
liver disease. |
4. POSSIBLE SIDE EFFECTS
|
How Common? |
Side Effects to Know About |
|
Common (>1 in 10) |
Urinary tract infection
(up to 3%), rapid heartbeat/palpitations (about 1%), headache, stuffy nose,
nausea, constipation, dry mouth (much lower rate than older bladder
medicines) |
|
Less Common |
Raised blood pressure,
dizziness, irregular heartbeat (atrial fibrillation), ankle swelling, skin
rash or itching, joint pain |
|
Seek Medical Help |
Severe allergic reaction
(stop and seek emergency help if face/throat swelling or difficulty
breathing). Inability to urinate (urinary retention) — especially if also
taking anticholinergic medicines. Atrial fibrillation (irregular heart
rhythm). |
5. WHO SHOULD NOT TAKE THIS
MEDICINE
Severe, uncontrolled high blood pressure
(systolic ≥180 mmHg or diastolic ≥110 mmHg). End-stage kidney disease (eGFR
<15 mL/min). Severe liver disease (Child-Pugh Class C). Known allergy to
mirabegron or any ingredient in Betmiga.
|
⚠
IMPORTANT SAFETY INFORMATION: BLOOD PRESSURE: Mirabegron
can raise blood pressure. Check your blood pressure regularly, especially
when first starting treatment. If you have high blood pressure, ensure it is
well controlled before starting. URINARY RETENTION: If you
are also taking anticholinergic bladder medicines, or have a bladder outlet
obstruction, the risk of being unable to urinate at all is increased. HEART:
Betmiga may cause a fast or irregular heartbeat — tell your doctor if you feel
palpitations or chest discomfort. |
6. MEDICINES THAT INTERACT
WITH THIS TREATMENT
Digoxin (heart medicine): Mirabegron
increases digoxin levels — a digoxin blood test is recommended before starting
Betmiga. Certain heart medicines (metoprolol, flecainide) and some
antidepressants, such as mirabegron, may increase their levels in the blood. Ketoconazole
and other strong CYP3A4 inhibitors: increase mirabegron levels. Anticholinergic
bladder medicines (solifenacin, darifenacin, tolterodine): combination is
approved but monitor for urinary retention.
7. HOW TO STORE THIS
MEDICINE
Store below 30°C. Keep in the original
blister packaging away from heat and moisture. Keep out of reach of children.
8. PRESCRIPTION REQUIREMENT
|
Status |
Prescription Only Medicine
(POM) |
9. GUIDANCE FOR PATIENTS
& CAREGIVERS
Take one Betmiga tablet at the same time
each day. Do not crush or split the tablet. Betmiga may take up to 8 weeks to
make a noticeable difference — do not stop taking it if you do not feel
immediate results. Check your blood pressure regularly. If you notice a fast heartbeat,
inability to urinate, facial swelling, or shortness of breath, contact your
doctor. Betmiga works differently from older bladder tablets (like oxybutynin)
and is less likely to cause dry mouth and constipation. Keep taking it as
prescribed even as your symptoms improve.
10. PHARMACIST &
PRESCRIBER NOTES
|
Clinical Dispensing Notes |
Betmiga is a beta-3
agonist — different mechanism from anticholinergics, lower dry-mouth burden.
Check BP and heart rate before initiation. Key interaction: check for digoxin
co-prescription (check digoxin levels) and CYP2D6 substrates (metoprolol,
TCAs). Counsel that therapeutic benefit takes 4–8 weeks. Combination with
anticholinergics is possible (approved) but increases urinary retention risk
— monitor. |
11.
FREQUENTLY ASKED QUESTIONS
Q: How is Betmiga different from other
overactive bladder tablets like oxybutynin?
A: Betmiga works through a completely
different mechanism — it activates beta-3 receptors to relax the bladder,
whereas older medicines (anticholinergics) block bladder nerve signals. The
practical difference is that Betmiga causes far less dry mouth and constipation
than anticholinergic medicines, which many patients find more tolerable.
Q: How long does it take for Betmiga to
work?
A: Most patients notice some improvement
within the first 4 weeks, with the full benefit usually seen after 8 weeks of
consistent daily use. Do not give up after just a few days — it takes time.
Q: Can I take Betmiga if I have high
blood pressure?
A: Betmiga can raise blood pressure
slightly, so your blood pressure must be well-controlled before you start. It is not recommended for people with severe
uncontrolled hypertension. Regular BP monitoring is advised during treatment.
Q: Can Betmiga be taken with other
bladder medicines?
A: Yes — Betmiga can be combined with
anticholinergic bladder medicines like solifenacin for better results in some
patients. However, the combination slightly increases the risk of being unable
to urinate (urinary retention). Discuss this with your doctor.
Q: Does Betmiga cause weight gain?