Farlosin SR Mechanism of Action

Pharmacotherapeutic group: α1-adrenoceptor antagonist.
Pharmacology: Pharmacodynamics: Mechanism of action: Tamsulosin binds selectively and competitively to the postsynaptic α1-adrenoceptors, in particular to subtypes α1A and α1D. It brings about relaxation of prostatic and urethral smooth muscle.
Pharmacodynamic effects: Farlosin SR 0.4 mg increases the maximum urinary flow rate.
It relieves obstruction by relaxing smooth muscle in prostate and urethra thereby improving voiding symptoms.
It also improves the storage symptoms in which bladder instability plays an important role.
These effects on storage and voiding symptoms are maintained during long-term therapy. The need for surgery or catheterization is significantly delayed.
A1-adrenoceptor antagonists can reduce blood pressure by lowering peripheral resistance. No reduction in blood pressure of any clinical significance was observed during studies with Tamsulosin 0.4 mg.
Pharmacokinetics: The pharmacokinetics parameters of 30 subjects (34 subjects were included in the study, 4 subjects were dropped out/were withdrawn from study) were calculated and results were statistically analyzed to demonstrate bioequivalence in a randomized, balanced, open label, two-sequence, two-treatment, two-period, two-way crossover design study. After oral administration of single dose of Tamsulosin 0.4 mg (test product) in the fasted state, the mean of the maximum plasma concentration (C_max) (rate of absorption) was 2.34 ng/mL, the median T_max was 3.07 h. The extent of absorption is expressed in Area Under the Curve (AUC)_0-72 and AUC_0-inf, the mean values were 110.59 ng.h/mL and 114.74 ng.h/mL respectively. The mean elimination half-life (T_½) of Tamsulosin 0.4 mg was 0.063 h.
The ratios and confidence intervals between test and reference product were as follows: for C_max the ratio was 105.4% (93.52%-118.89%). For AUC_0-72 the ratio was 107.2% (95.98%-119.79%). The results of the study showed that the ratios and confidence intervals are within the acceptance range for bioequivalence, therefore it can be concluded that the test product, Tamsulosin 0.4 mg sustained release tablets, is bioequivalence with the reference product.