- Significant peak urine flow (Qmax) improvements within 2-6 hours of the
first dose, according to published data -
CORONA, Calif., May 8 /PRNewswire-FirstCall/ -- RAPAFLO(TM) (silodosin), a
new, uniquely selective alpha blocker for the treatment of the signs and
symptoms of BPH, produces rapid improvements of both irritative and
obstructive urinary symptoms that were sustained for 12 weeks, according to
data published in the June issue of The Journal of Urology. RAPAFLO(TM) was
developed and is manufactured by Watson Pharmaceuticals, a leader in generic
and specialty branded pharmaceuticals.
In an analysis of data pooled from two Phase 3 studies, patients taking
RAPAFLO(TM) demonstrated statistically significant symptom relief versus
placebo within three to four days of starting treatment, and remained
significant throughout the 12-week study period.
"The severity of urinary symptoms appears to depend in part on smooth
muscle tone in the prostate and bladder neck, which is mediated by alpha 1A
adrenoreceptors," said Leonard S. Marks, MD, author of the study and professor
of urology at the Geffen School of Medicine, the University of California at
Los Angeles. "The data indicate that RAPAFLO(TM) (silodosin) induces
effective relaxation of the targeted prostatic muscle tissue, with a low
incidence of vasodilatory and orthostatic effects. RAPAFLO(TM) (silodosin) is
a fast acting, effective and safe treatment for the signs and symptoms
associated with BPH."
BPH is the number one reason patients visit urologists and is
characterized by urination problems, including decreased urine flow, more
frequent urination and nocturia.
Clinical Trial Results
The new paper is a pooled analysis of two, 12-week, randomized,
placebo-controlled, double-blind multi-center clinical trials involving 923
generally healthy men ages 50 or older with signs and symptoms of BPH,
including a peak urine flow rate (Qmax) between 4 and 15 mL/sec (mean of 8.7
to 8.9) and International Prostate Symptom Score (IPSS) greater than or equal
to 13 (mean of 21.3). IPSS includes irritative (frequency, urgency, and
nocturia), and obstructive (hesitancy, incomplete emptying, intermittency, and
weak stream) symptoms. Patients were randomized to either 8 mg RAPAFLO(TM)
(n=466) or placebo (n=457) taken once daily with breakfast for 12 weeks.
The primary endpoint was change in IPSS from baseline to the last
observation, including sub-scores related to irritative symptoms and
obstructive symptoms. Change in peak urinary flow rate (Qmax scores) was a
At the last observation, patients treated with RAPAFLO(TM) versus placebo
experienced significantly greater changes in total IPSS from baseline measures
(-6.4 vs. -3.5, respectively; p<0.0001), as well as irritative (-2.3 vs. -1.4,
respectively; p<0.0001) and obstructive (-4.0 vs. -2.1, respectively;
p<0.0001) sub-scores. These differences were significantly better for
RAPAFLO(TM) vs. placebo after three to four days of treatment (p<0.0001 for
total IPSS and obstructive sub-score; p=0.0002 for irritative sub-score).
RAPAFLO(TM) also significantly improved Qmax scores as early as two to six
hours after the first dose and was sustained through 12 weeks of treatment.
The most common drug-related adverse event (AE) was retrograde ejaculation
(orgasm with reduced semen), an expected treatment effect of selective alpha
blockers, which occurred in 28 percent of men treated with RAPAFLO(TM).
Retrograde ejaculation, a reversible treatment effect, led to treatment
discontinuation in only 2.8 percent of patients, and does not pose a safety
concern. Incidences of orthostatic hypotension among RAPAFLO(TM)- and
placebo-treated patients were similar and low (2.6% and 1.5%, respectively).
In addition, the incidence of treatment-related dizziness was only slightly
higher among RAPAFLO(TM)- than placebo-treated patients (3.2% vs. 1.1%).
RAPAFLO(TM) is an effective, uniquely selective alpha-1 adrenergic
receptor antagonist. RAPAFLO(TM) maximizes target organ activity by binding
with high affinity to the alpha (1A) receptors concentrated in the prostate.
The antagonism of these receptors cause the smooth muscles in these tissues to
relax and results in improved urine flow and a reduction in BPH symptoms. The
binding affinity for the alpha (1B) receptors that cause smooth muscle in
peripheral vessels is significantly lower, which may minimize orthostatic
The most common drug-related side effect was retrograde ejaculation. The
second most commonly-reported adverse event was dizziness. The incidence of
treatment-related dizziness was low and only slightly higher among RAPAFLO(TM)
than placebo-treated patients (11 vs. 3 patients).
Previously presented data included information that in clinical trials
RAPAFLO(TM) was administered with a single dose of medications for erectile
dysfunction in healthy male subjects (N=24) and that there were no reported
events of symptomatic orthostasis or dizziness. RAPAFLO(TM) demonstrated no
meaningful electro cardiac effects during Phase 3 trials and during thorough
QTc testing as required for new chemical entities by the FDA.
RAPAFLO(TM) was originally developed by Kissei Pharmaceutical Co., Ltd. in
Japan, where RAPAFLO(TM) is the BPH market leader, and licensed to Watson for
the U.S., Canada and Mexico markets.
About Watson Pharmaceuticals, Inc.
Watson Pharmaceuticals, Inc. (NYSE: WPI) is a global leader in the
development and distribution of pharmaceuticals with a broad portfolio of
generic products and a specialized portfolio of branded pharmaceuticals
focused on Urology, Gynecology and Nephrology (Medical).
In the U.S., the Watson portfolio includes RAPAFLO(TM), GELNIQUE(TM),
TRELSTAR(R) LA; TRELSTAR(R) Depot; Ferrlecit(R), INFeD(R) and Oxytrol(R). In
addition, Watson markets the following brands under co-promotion agreements:
AndroGel(R), with Solvay Pharmaceuticals, Inc., and Femring(R), with Warner
Chilcott Limited. The Watson pipeline portfolio includes a number of
products, including a six-month formulation of TRELSTAR(R), for the treatment
of advanced prostate cancer which is currently under review by the FDA;
URACYST(R), under development for cystitis; and a novel new oral
For press releases and other company information, visit the Watson website
Any statements contained in this press release that refer to future events
or other non-historical facts are forward-looking statements that reflect
Watson's current perspective of existing trends and information as of the date
of this release. Except as expressly required by law, Watson disclaims any
intent or obligation to update these forward-looking statements. Actual
results may differ materially from Watson's current expectations depending
upon a number of factors affecting Watson's business. These factors include,
among others, the impact of competitive products and pricing; market
acceptance of and continued demand for Watson's products, including
RAPAFLO(TM); difficulties or delays in manufacturing; patents and other
intellectual property rights held by the Company and the ability to
successfully enforce such rights against third parties; and other risks and
uncertainties detailed in Watson's periodic public filings with the Securities
and Exchange Commission, including but not limited to Watson's Annual Report
on Form 10-K for the year ended December 31, 2008.
SOURCE Watson Pharmaceuticals, Inc.
of Watson Pharmaceuticals, Inc.,
of Ogilvy Public Relations,
for Watson Pharmaceuticals, Inc.
Web Site: http://www.watsonpharm.com