Naftopidil Reported in Japanese Study to Be an Effective Drug Treatment for LUTS

Naftopidil Reported in Japanese Study to Be an Effective Drug Treatment for LUTS

The drug naftopidil improves benign prostatic hyperplasia (BPH)-associated urinary tract symptoms by modulating the plasma levels of adrenaline, according to the study, “Influence of Naftopidil on Plasma Monoamine Levels and Lower Urinary Tract Symptoms Associated with Benign Prostatic Hyperplasia” published in the journal LUTS: Lower Urinary Tract Symptoms.

BPH is characterized by a benign increase in prostate size, and causes complications that include lower urinary tract symptoms (LUTS) as a result of a narrowing of the urethra and functional obstruction. Current treatments include the use of alpha1-adrenergic receptor (α1-AR) antagonists, leading to muscle relaxation and decreased resistance to urine flow.

Naftopidil, an α1D/A-adrenergic receptor antagonist, is among those with high affinity for a subtype of the adrenergic receptor. Since the lower urinary tract is under the control of the autonomic nervous system, researchers — from hospitals and clinics in Okinawa, Japan — examined the relation between LUTS and plasma monoamine levels (key regulators of the autonomic nervous system) in BPH patients before and after naftopidil treatment. The drug was approved in Japan for the treatment of lower urinary tract symptoms related to BPH in 1999.

The team analyzed several parameters before and after naftopidil treatment in a total of 43 patients with BPH: frequency of urination, international prostate symptom score (IPSS), quality of life (QOL) index, overactive bladder symptom score (OABSS), and plasma monoamine levels (adrenaline, noradrenaline, dopamine, and serotonin).

They found that naftopidil significantly improved several of the parameters analyzed, including the frequency or urination (both during daytime and nighttime), IPSS, QOL index, and OABSS in all treated patients. The drug also led to a decrease in plasma adrenaline levels at eight weeks of treatment.

Authors further investigated the role of naftopidil and adrenaline, and divided patients into two groups based on the median adrenaline level (40.5 pg/mL) before treatment. They observed that urinary frequency (daytime and/or nighttime), incomplete emptying and poor flow in the IPSS, and the QOL index significantly improved in the high adrenaline group, but not in the low adrenaline group. Serotonin levels, although lower in the beginning of the study in the high adrenaline group, were no different between high and low adrenaline groups at the end of the analysis.

Results, the team concluded, show that naftopidil modulation of plasma adrenaline and serotonin levels improves LUTS associated with BPH.

BPH is a common disorder affecting elderly men, and estimates are that 50 percent of men, age 60 or older, suffer from BPH, a number that increases to 80 percent in those over age 80.

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