Betmiga 50 mg

Indications

• Overactive bladder (OAB) symptoms
• Urinary urgency
• Urinary frequency
• Urge incontinence

Dosage

Children: Safety and efficacy in children have not been established; refer to the BNF for Children for further guidance.

Adults: The recommended dose for adults is 60 mg once daily. For patients with renal impairment, dose adjustments may be required.

Mechanism of action

Mirabegron acts as a potent and selective agonist of the beta-3 adrenergic receptors. Upon activation, these receptors relax the detrusor smooth muscle during the storage phase of the bladder fill-void cycle, which enhances the bladder's storage capacity and alleviates feelings of urinary urgency and frequency.

Pharmacodynamics

The pharmacologic effects of mirabegron include the relaxation of bladder smooth muscle, which allows for increased capacity and relief from urgency. Unlike anticholinergic medications, mirabegron does not significantly impact the mean maximum flow rate or detrusor pressure in patients with lower urinary tract symptoms or bladder outlet obstruction (BOO). However, it can increase blood pressure and heart rate in a dose-dependent manner, warranting caution in patients with severely uncontrolled hypertension or those at risk for cardiovascular events.

Pharmacokinetics

Mirabegron is well-absorbed after oral administration, with peak plasma concentrations typically occurring within 3 to 4 hours. It undergoes extensive hepatic metabolism primarily via CYP2D6, with renal excretion of metabolites. The half-life of mirabegron is approximately 50 hours, allowing for once-daily dosing. Its pharmacokinetics may be affected by renal and hepatic function, requiring caution and possible dose adjustments in patients with varying degrees of impairment.

Adverse effects

• Hypertension
• Urinary retention
• Tachycardia
• Headache
• Dry mouth
• Nausea
• Diarrhea
• Constipation
• Dizziness
• Fatigue

Interactions

• Digoxin (moderate - increases exposure)
• Eliglustat (moderate - increases exposure)
• Aliskiren (unknown - increases exposure)
• Fexofenadine (unknown - increases exposure)
• Metoprolol (unknown - increases exposure)
• Cobicistat (unknown - increases exposure)
• Colchicine (unknown - increases exposure)
• Everolimus (unknown - increases exposure)
• Edoxaban (unknown - increases exposure)
• Idelalisib (unknown - increases exposure)

Precautions

• History of QT-interval prolongation
• Severe uncontrolled hypertension
• Bladder outlet obstruction (BOO)
• Hepatic impairment
• Renal impairment

Pregnancy

Manufacturer advises caution due to potential toxicity in animal studies.

Breast-feeding

Manufacturer advises caution, no information available on excretion in breast milk.

Storage

Store at room temperature, protect from moisture and light.

Formulations

• Modified-release capsules
• Tablets

Dosage

Children: Refer to the specific drug's prescribing information for paediatric dosage recommendations, as it can vary based on the active ingredient and condition treated.

Adults: Refer to the specific drug's prescribing information for adult dosage recommendations, as it can vary widely based on the active ingredient and condition treated.

Mechanism of action

The mechanism of action for prolonged-release formulations typically involves the controlled release of active ingredients through various matrix systems, such as hydrophilic or hydrophobic matrices. These systems allow the drug to be released slowly over time, maintaining therapeutic levels in the bloodstream and reducing the frequency of dosing.

Pharmacodynamics

The pharmacodynamics of prolonged-release drugs depend on the active component and formulation. Generally, these medications aim to provide a steady-state concentration of the drug in the plasma, leading to sustained therapeutic effects with minimized peak-trough fluctuations. This can enhance efficacy and reduce side effects.

Pharmacokinetics

Pharmacokinetics of prolonged-release formulations usually involve altered absorption profiles, with slower absorption rates compared to immediate-release forms. The distribution, metabolism, and excretion of the active ingredient may remain similar to the parent compound, but the extended release can affect the overall bioavailability and duration of action. Factors like food intake, gastrointestinal motility, and patient-specific variables (age, weight, organ function) can influence the pharmacokinetics of these formulations.

Pregnancy

The safety of prolonged use during pregnancy is not well established. Consult a healthcare provider for advice on specific situations.

Breast-feeding

It is not clear whether prolonged use affects breast milk. Consult a healthcare provider for guidance on breastfeeding while using this drug.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Dosage

Children: Refer to specific drug guidelines for dosing information, as it varies by medication.

Adults: Refer to specific drug guidelines for dosing information, as it varies by medication.

Mechanism of action

The mechanism of action would depend on the specific drug referred to as 'released'. Generally, pharmacological agents may act through various pathways such as receptor binding, enzyme inhibition, or modulation of physiological processes. For example, some medications may function as agonists or antagonists at specific receptors, influencing cellular signaling pathways and physiological responses.

Pharmacodynamics

Pharmacodynamics describes the effects of the drug on the body, including the relationship between drug concentration and effect. This may vary significantly based on the specific medication. Factors such as drug-receptor interactions, therapeutic index, and side effects are crucial to understanding its pharmacodynamics. Typically, the efficacy and potency of the drug are assessed through clinical outcomes and dose-response relationships.

Pharmacokinetics

Pharmacokinetics involves the absorption, distribution, metabolism, and excretion of the drug. The specific pharmacokinetic profile would depend on the drug in question. Generally, pharmacokinetic parameters such as bioavailability, half-life, volume of distribution, and clearance rates are essential for determining dosing regimens and predicting therapeutic outcomes.

Pregnancy

Safety during pregnancy has not been established. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Use with caution. It is not known whether released is excreted in human milk.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Mechanism of action

Mirabegron is a potent and selective agonist of beta-3 adrenergic receptors. The activation of beta-3 receptors relaxes detrusor smooth muscle during the storage phase of the urinary bladder fill-void cycle, which increases the bladder's storage capacity thereby alleviating feelings of urgency and frequency.

Pharmacodynamics

Mirabegron exerts its pharmacologic effects by forcing bladder smooth muscle to relax, thereby expanding its capacity and relieving urgency. Mirabegron does not appear to adversely affect the mean maximum flow rate or mean detrusor pressure at maximum flow rate in patients with lower urinary tract symptoms and bladder outlet obstruction (BOO), but should be used with in patients with BOO due to reports of significant urinary retention. Furthermore, mirabegron increases both blood pressure and heart rate in a dose-dependent manner and should therefore be used with caution in patients with severely uncontrolled hypertension or others for whom these increases may prove dangerous.