Pediatric Use
FLOMAX capsules are
not indicated for use in pediatric populations [see Use in Specific Populations (8.4)
].
Geriatric (Age) Use
Cross-study comparison of FLOMAX capsules
overall exposure (AUC) and half-life indicates that the pharmacokinetic
disposition of tamsulosin hydrochloride may be slightly prolonged
in geriatric males compared to young, healthy male volunteers. Intrinsic
clearance is independent of tamsulosin hydrochloride binding to AAG,
but diminishes with age, resulting in a 40% overall higher exposure
(AUC) in subjects of age 55 to 75 years compared to subjects of age
20 to 32 years [see Use in Specific Populations (8.5)
].
Renal Impairment
The pharmacokinetics of tamsulosin
hydrochloride have been compared in 6 subjects with mild-moderate
(30≤ CLcr <70 mL/min/1.73 m2) or moderate-severe (10≤ CLcr <30 mL/min/1.73 m2) renal impairment
and 6 normal subjects (CLcr >90 mL/min/1.73
m2). While a change in the overall plasma
concentration of tamsulosin hydrochloride was observed as the result
of altered binding to AAG, the unbound (active) concentration of tamsulosin
hydrochloride, as well as the intrinsic clearance, remained relatively
constant. Therefore, patients with renal impairment do not require
an adjustment in FLOMAX capsules dosing. However, patients with end-stage
renal disease (CLcr <10 mL/min/1.73 m2) have not been studied [see Use
in Specific Populations (8.6)
].
Hepatic Impairment
The pharmacokinetics of tamsulosin hydrochloride
have been compared in 8 subjects with moderate hepatic impairment
(Child-Pugh’s classification: Grades A and B) and 8 normal subjects.
While a change in the overall plasma concentration of tamsulosin
hydrochloride was observed as the result of altered binding to AAG,
the unbound (active) concentration of tamsulosin hydrochloride does
not change significantly, with only a modest (32%) change in intrinsic
clearance of unbound tamsulosin hydrochloride. Therefore, patients
with moderate hepatic impairment do not require an adjustment in FLOMAX
capsules dosage. FLOMAX has not been studied in patients with severe
hepatic impairment [see Use in Specific Populations (8.7)
].
Drug Interactions
Cytochrome P450 Inhibition
Strong and Moderate Inhibitors of
CYP3A4 or CYP2D6
The effects of ketoconazole (a
strong inhibitor of CYP3A4) at 400 mg once daily for 5 days on the
pharmacokinetics of a single FLOMAX capsule 0.4 mg dose was investigated
in 24 healthy volunteers (age range 23 to 47 years). Concomitant treatment
with ketoconazole resulted in an increase in the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)
]. The effects of concomitant administration
of a moderate CYP3A4 inhibitor (e.g., erythromycin) on the pharmacokinetics
of FLOMAX have not been evaluated [see Warnings
and Precautions (5.2) and Drug Interactions (7.1)
].
The effects of paroxetine (a strong inhibitor
of CYP2D6) at 20 mg once daily for 9 days on the pharmacokinetics
of a single FLOMAX capsule 0.4 mg dose was investigated in 24 healthy
volunteers (age range 23 to 47 years). Concomitant treatment with
paroxetine resulted in an increase in the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively [see Warnings and Precautions (5.2) and Drug Interactions (7.1)
]. A similar increase in exposure is expected in CYP2D6
poor metabolizers (PM) as compared to extensive metabolizers (EM).
A fraction of the population (about 7% of Caucasians and 2% of African
Americans) are CYP2D6 PMs. Since CYP2D6 PMs cannot be readily identified
and the potential for significant increase in tamsulosin exposure
exists when FLOMAX 0.4 mg is co-administered with strong CYP3A4 inhibitors
in CYP2D6 PMs, FLOMAX 0.4 mg capsules should not be used in combination
with strong inhibitors of CYP3A4 (e.g., ketoconazole) [see Warnings and Precautions (5.2) and Drug Interactions (7.1)
].
The effects
of concomitant administration of a moderate CYP2D6 inhibitor (e.g.,
terbinafine) on the pharmacokinetics of FLOMAX have not been evaluated
[see Warnings and Precautions (5.2) and Drug Interactions (7.1)
].
The effects of co-administration of both a CYP3A4 and a CYP2D6 inhibitor
with FLOMAX capsules have not been evaluated. However, there is a
potential for significant increase in tamsulosin exposure when FLOMAX
0.4 mg is co-administered with a combination of both CYP3A4 and CYP2D6
inhibitors [see Warnings and Precautions (5.2) and Drug Interactions (7.1)
].
Cimetidine
The effects of cimetidine at
the highest recommended dose (400 mg every 6 hours for 6 days) on
the pharmacokinetics of a single FLOMAX capsule 0.4 mg dose was investigated
in 10 healthy volunteers (age range 21 to 38 years). Treatment with
cimetidine resulted in a significant decrease (26%) in the clearance
of tamsulosin hydrochloride, which resulted in a moderate increase
in tamsulosin hydrochloride AUC (44%) [see Warnings
and Precautions (5.2) and Drug Interactions (7.1)
].
Other Alpha Adrenergic Blocking
Agents
The pharmacokinetic and pharmacodynamic interactions between FLOMAX
capsules and other alpha adrenergic blocking agents have not been
determined; however, interactions between FLOMAX capsules and other
alpha adrenergic blocking agents may be expected [see Warnings and Precautions (5.2) and Drug Interactions (7.2)
].
PDE5 Inhibitors
Caution is advised when alpha adrenergic
blocking agents, including FLOMAX, are co-administered with PDE5 inhibitors.
Alpha-adrenergic blockers and PDE5 inhibitors are both vasodilators
that can lower blood pressure. Concomitant use of these two drug classes
can potentially cause symptomatic hypotension [see
Warnings and Precautions (5.2) and
Drug Interactions (7.3)
].
Warfarin
A definitive drug-drug interaction study between tamsulosin hydrochloride
and warfarin was not conducted. Results from limited in vitro and in vivo studies are inconclusive. Therefore, caution should be
exercised with concomitant administration of warfarin and FLOMAX capsules
[see Warnings and Precautions (5.2) and Drug Interactions (7.4)
].
Nifedipine, Atenolol, Enalapril
In three studies in hypertensive
subjects (age range 47 to 79 years) whose blood pressure was controlled
with stable doses of nifedipine, atenolol, or enalapril for at least
3 months, FLOMAX capsules 0.4 mg for 7 days followed by FLOMAX capsules
0.8 mg for another 7 days (n=8 per study) resulted in no clinically
significant effects on blood pressure and pulse rate compared to placebo
(n=4 per study). Therefore, dosage adjustments are not necessary
when FLOMAX capsules are administered concomitantly with nifedipine,
atenolol, or enalapril [see Drug Interactions (7.5)
].
Digoxin and Theophylline
In two studies in healthy volunteers
(n=10 per study; age range 19 to 39 years) receiving FLOMAX capsules
0.4 mg/day for 2 days, followed by FLOMAX capsules 0.8 mg/day for
5 to 8 days, single intravenous doses of digoxin 0.5 mg or theophylline
5 mg/kg resulted in no change in the pharmacokinetics of digoxin or
theophylline. Therefore, dosage adjustments are not necessary when
a FLOMAX capsule is administered concomitantly with digoxin or theophylline
[see Drug Interactions (7.6)
].
Furosemide
The pharmacokinetic and pharmacodynamic interaction between FLOMAX
capsules 0.8 mg/day (steady-state) and furosemide 20 mg intravenously
(single dose) was evaluated in 10 healthy volunteers (age range 21
to 40 years). FLOMAX capsules had no effect on the pharmacodynamics
(excretion of electrolytes) of furosemide. While furosemide produced
an 11% to 12% reduction in tamsulosin hydrochloride Cmax and AUC, these changes are expected to be clinically insignificant
and do not require adjustment of the FLOMAX capsules dosage [see Drug Interactions (7.7)
].