Betmiga® [Mirabegron]

Pharmacological properties

Pharmacodynamics

Mechanism of action. Mirabegron is a potent selective β agonist₃-adrenoreceptors. Under the influence of mirabegron, relaxation of the smooth muscles of the bladder in animals and in isolated human tissue occurs, an increase in the concentration of cAMP in the tissues of the bladder of animals and a relaxing effect on the bladder is observed on a functioning model of the bladder in animals.

Mirabegron increases the average volume of urine during urination and reduces the frequency of urination without contraction of the muscles of the bladder outside of urination without the influence of pressure or residual urine on the bladder cavity in an overactive bladder model of animals. In animal bladder models, mirabegron showed a decrease in urination frequency. These results show that mirabegron enhances urinary retention by stimulating β₃-adrenoreceptors in the muscles of the bladder.

Stimulation of receptors of the sympathetic nervous system prevails at the stage of urine retention, when urine accumulates in the bladder. Norepinephrine is released from the nerve endings, stimulating mainly β-adrenergic receptors in the muscle tissue of the bladder, and, accordingly, relaxes the smooth muscles of the bladder. In the phase of urine accumulation, the bladder is mainly controlled by the parasympathetic nervous system. Acetylcholine, which is released in the pelvic nerve endings, stimulates cholinergic M₂- and M₃receptors, causing a contraction of the bladder. Activation M₂-path also suppresses β₃-adrenoreceptors, increasing cAMP. Therefore, stimulation of β₃-adrenoreceptors does not affect the process of urine accumulation. This is confirmed in models with partial urethral obstruction, where mirabegron reduced the frequency of contraction of the bladder without contraction of the muscles of the bladder outside of urination without the effect of pressure or residual urine on the bladder cavity.

Pharmacokinetics

Absorption. Following oral administration in healthy volunteers, mirabegron is absorbed into the bloodstream and reaches C_max blood plasma 3 or 4 hours after administration. Bioavailability increases from 29 to 35% after increasing the dose from 25 to 50 mg. Moreover, the average values ​​of C_max and AUC increased more than proportionally for the indicated dose range. In the general population of men and women with a 2-fold increase in the dose of mirabegron from 50 to 100 mg, an increase in C was observed_max and increase in AUC_tau approximately 2.9 and 2.6 times, respectively, while a 4-fold increase in the dose of mirabegron from 50 to 200 mg induces an increase in C_max and increase in AUC_tau approximately 8.4 and 6.5 times. Persistent concentration is achieved within 7 days (taking mirabegron once a day). After that, with the introduction of 1 time per day, the level of mirabegron in blood plasma is maintained in a stable state about 2 times higher than after a single dose.

Indications

Symptomatic treatment for urgent urination, an increase in the frequency of urination and / or urinary incontinence, which can occur in adult patients with overactive bladder syndrome (SGMP).

Application

Adults, including elderly patients. the recommended dose is 50 mg 1 time per day, regardless of food intake.

Renal and liver failure. The use of Betmiga in patients with end-stage renal failure has not been investigated (GFR 15 ml / min / 1.73 m², or in patients requiring hemodialysis) or in people with severe hepatic insufficiency (Child-Pugh class C), therefore Betmiga is not recommended for these categories of patients (see SPECIAL INSTRUCTIONS, Pharmacokinetics).

In the table. 1 provides daily dosage recommendations for patients with renal or hepatic insufficiency in the presence or absence of potent CYP 3A inhibitors (see SPECIAL INSTRUCTIONS, INTERACTIONS, Pharmacokinetics).

¹Moderate: GFR 60–89 ml / min / 1.73 m²; average: GFR 30–59 ml / min / 1.73 m²; heavy: GFR 15–29 ml / min / 1.73 m².

²Moderate: Child A-Pugh class A; Medium: Child B - Class B class.

³Powerful CYP 3A inhibitors see INTERACTIONS.

Tablets should be taken 1 time per day, washed down with liquid; swallow the tablet whole; the tablet should not be chewed, divided into parts or crushed.

Floor. There is no need to change the dose.

Contraindications

Hypersensitivity to the active substance or to any of the excipients.

Side effects

Most adverse reactions were mild or moderate.

The most common adverse reactions were tachycardia and urinary tract infections. The frequency of tachycardia was 1.2% and led to the cessation of treatment in 0.1% of patients. The incidence of urinary tract infections was 2.9%. Urinary tract infections did not stop treatment in any of the patients. Serious adverse reactions included atrial fibrillation (0.2%).

The frequency of adverse reactions is determined as follows: very often (≥1 / 10); often (≥1 / 100 to 1/10); infrequently ≥1 / 1000 to 1/100), rarely (≥1 / 10,000 to 1/1000), very rarely (1/10 000). In each group, adverse reactions are presented in decreasing order of severity.