Pharmacological properties
Pharmacodynamics. Tamsulosin is an α1-adrenoceptor antagonist.
Tamsulosin selectively blocks postsynaptic α 1 -adrenoreceptors located in the smooth muscles of the prostate gland, bladder neck and prostatic part of the urethra. This leads to a decrease in the tone of the smooth muscles of the prostate gland, bladder neck and prostatic part of the urethra and an improvement in urine outflow. At the same time, the symptoms of obstruction and irritation associated with benign prostatic hyperplasia are reduced. As a rule, the therapeutic effect develops 2 weeks after the start of taking the drug.
Pharmacokinetics. Absorption. After oral administration, tamsulosin is rapidly and almost completely absorbed from the gastrointestinal tract. Absorption is reduced by prior food intake. Tamsulosin is characterized by linear kinetics.
C max in blood plasma is reached after 6 hours.
Distribution. Binding to plasma proteins is 99%. The volume of distribution is insignificant - up to 0.2 l/kg.
Metabolism: Tamsulosin hydrochloride is not subject to the first-pass effect and is slowly metabolized in the liver to form pharmacologically active metabolites that retain high selectivity for α1-adrenoceptors. Most of the active substance is detected in the blood in unchanged form.
Excretion. Tamsulosin hydrochloride is excreted by the kidneys, 9% of the dose is excreted unchanged. T ½ of tamsulosin with a single dose is 10 hours, the final T ½ is 13 hours.
Indication
Treatment of functional disorders of the lower urinary tract in benign prostatic hyperplasia.
Application
Doses and duration of treatment should be selected individually. The recommended dose for adults is 1 capsule per day. Take after breakfast. The capsule should be swallowed whole with sufficient water, standing or sitting. The capsule should be taken without breaking, as this will prevent the modified release of the active ingredient.
Contraindication
Hypersensitivity reactions, including angioedema, to tamsulosin hydrochloride or any other component of the drug; orthostatic hypotension; severe hepatic insufficiency.
Side effects
Common side effects (1/100, 1/10)
Central nervous system: dizziness.
From the reproductive system: retrograde ejaculation.
Uncommon (1/1000, 1/100)
Central nervous system: headache.
Cardiovascular system: palpitations, orthostatic hypotension.
Respiratory and mediastinal disorders: rhinitis.
Gastrointestinal: constipation, diarrhea, nausea, vomiting.
Skin and mucous membranes: rash, urticaria, itching.
General disorders: asthenia.
Rare (1/10,000, 1/1000)
Central nervous system: fainting.
Skin and mucous membranes: angioedema.
Very rare (1/10,000)
From the reproductive system: priapism.
Skin and subcutaneous tissue disorders: Stevens-Johnson syndrome.
There have been spontaneous reports of atrial fibrillation, arrhythmia, tachycardia and dyspnea in the post-marketing period; the frequency of reports and the role of tamsulosin in this case cannot be reliably established.
Cases of intraoperative iris instability (pinched pupil syndrome) during cataract and glaucoma surgery have been described in patients who have taken tamsulosin for a long time (see Precautions).
Special instructions
Iris instability (pinched pupil syndrome) associated with α1-adrenergic blockade during cataract and glaucoma surgery has been reported in some patients who have taken or are taking tamsulosin. For this reason, tamsulosin is not recommended for patients scheduled for cataract and glaucoma surgery.
As a rule, it is recommended to stop tamsulosin treatment 1-2 weeks before cataract and glaucoma surgery. However, the appropriateness and timing of stopping tamsulosin treatment have not been precisely established to date.
When preparing for surgery, ophthalmologists should find out whether the patient has taken (or is taking) tamsulosin in order to prevent possible complications associated with iris instability.
As with other α1-adrenergic blockers, in rare cases, when using Tamsulosin, a decrease in blood pressure is possible, which can sometimes lead to loss of consciousness. At the first signs of orthostatic hypotension (dizziness, weakness), the patient should take a horizontal position until the above symptoms disappear.
It should be prescribed with extreme caution to patients with severe renal insufficiency (creatinine clearance 10 ml/min), since clinical studies using Tamsulostad have not been conducted in such patients.
Tamsulosin hydrochloride should not be administered in combination with strong CYP 3A4 inhibitors in patients with poor CYP 2D6 metabolism.
Tamsulosin hydrochloride should be used with caution in combination with strong and moderate CYP 3A4 inhibitors (see Interactions with other drugs).
Use during pregnancy and lactation: Tamsulostad is indicated for use in men only.
Children. The drug is not used in children.
The ability to influence the reaction rate when driving vehicles or working with other mechanisms. Studies of the effect of the drug on the ability to drive vehicles or work with complex mechanisms have not been conducted. However, patients should be warned about the possibility of dizziness.
Interactions
No interaction occurs with the simultaneous use of tamsulosin hydrochloride with atenolol, enalapril, nifedipine or theophylline.
With simultaneous use with cimetidine, an increase in the concentration of tamsulosin in the blood plasma was observed, and with furosemide - a decrease in concentration, however, since these levels remain within normal limits, there is no need for special dose adjustment of tamsulosin.
In in vitro studies, diazepam, propranolol, trichlormethiazide, chlormadinone, amitriptyline, diclofenac, glibenclamide, simvastatin and warfarin did not affect the free fraction of tamsulosin in human plasma. Similarly, tamsulosin did not change the free fractions of diazepam, propranolol, trichlormethiazide and chlormadinone in human plasma.
Concomitant use of tamsulosin hydrochloride with strong CYP 3A4 inhibitors may lead to increased exposure to tamsulosin hydrochloride. Concomitant use with ketoconazole (a known strong CYP 3A4 inhibitor) results in an increase in Cmax and AUC to 2.2 and 2.8, respectively.
Concomitant use of tamsulosin hydrochloride and paroxetine (a strong CYP 2D6 inhibitor) leads to an increase in Cmax and AUC to 1.3 and 1.6, respectively, but this is not clinically significant.
Tamsulosin hydrochloride should not be administered in combination with strong CYP 3A4 inhibitors in patients with poor CYP 2D6 metabolism.
Tamsulosin hydrochloride should be used with caution in combination with strong and moderate CYP 3A4 inhibitors.
Concomitant use with other α1-adrenoceptor blockers may enhance the hypotensive effect.
Overdose
In case of a sharp decrease in blood pressure due to overdose, supportive therapy should be carried out, aimed at restoring normal cardiovascular function (for example, the patient should take a horizontal position). If this measure is not effective, infusion therapy is carried out and vasopressor agents are prescribed. It is necessary to monitor renal function and carry out general supportive therapy. Due to the high degree of binding of tamsulosin to plasma proteins, hemodialysis is unlikely to be advisable.
In order to stop further absorption of the drug, vomiting can be induced artificially. In case of overdose of a significant amount of the drug, the patient should be washed with activated charcoal and low-osmotic laxatives, such as sodium sulfate.
Storage conditions
In the original packaging at a temperature not exceeding 25 °C.
