Signs and Symptoms of Orthostasis
In the two U.S. studies, symptomatic postural hypotension was reported by 0.2% of patients (1 of 502) in the 0.4 mg group, 0.4% of patients (2 of 492) in the 0.8 mg group, and by no patients in the placebo group. Syncope was reported by 0.2% of patients (1 of 502) in the 0.4 mg group, 0.4% of patients (2 of 492) in the 0.8 mg group, and 0.6% of patients (3 of 493) in the placebo group. Dizziness was reported by 15% of patients (75 of 502) in the 0.4 mg group, 17% of patients (84 of 492) in the 0.8 mg group, and 10% of patients (50 of 493) in the placebo group. Vertigo was reported by 0.6% of patients (3 of 502) in the 0.4 mg group, 1% of patients (5 of 492) in the 0.8 mg group, and by 0.6% of patients (3 of 493) in the placebo group.
Multiple testing for orthostatic hypotension was conducted in a number of studies. Such a test was considered positive if it met one or more of the following criteria: (1) a decrease in systolic blood pressure of ≥20 mmHg upon standing from the supine position during the orthostatic tests; (2) a decrease in diastolic blood pressure ≥10 mmHg upon standing, with the standing diastolic blood pressure <65 mmHg during the orthostatic test; (3) an increase in pulse rate of ≥20 bpm upon standing with a standing pulse rate ≥100 bpm during the orthostatic test; and (4) the presence of clinical symptoms (faintness, lightheadedness/lightheaded, dizziness, spinning sensation, vertigo, or postural hypotension) upon standing during the orthostatic test.
Following the first dose of double-blind medication in Study 1, a positive orthostatic test result at 4 hours post dose was observed in 7% of patients (37 of 498) who received FLOMAX capsules 0.4 mg once daily and in 3% of the patients (8 of 253) who received placebo. At 8 hours post dose, a positive orthostatic test result was observed for 6% of the patients (31 of 498) who received FLOMAX capsules 0.4 mg once daily and 4% (9 of 250) who received placebo (Note: patients in the 0.8 mg group received 0.4 mg once daily for the first week of Study 1).
In Studies 1 and 2, at least one positive orthostatic test result was observed during the course of these studies for 81 of the 502 patients (16%) in the FLOMAX capsules 0.4 mg once-daily group, 92 of the 491 patients (19%) in the FLOMAX capsules 0.8 mg once-daily group, and 54 of the 493 patients (11%) in the placebo group.
Because orthostasis was detected more frequently in FLOMAX capsule-treated patients than in placebo recipients, there is a potential risk of syncope
[see
Warnings and Precautions (5.1)]
.
Abnormal Ejaculation
Abnormal ejaculation includes ejaculation failure, ejaculation disorder, retrograde ejaculation, and ejaculation decrease. As shown in Table 1, abnormal ejaculation was associated with FLOMAX capsules administration and was dose-related in the U.S. studies. Withdrawal from these clinical studies of FLOMAX capsules because of abnormal ejaculation was also dose-dependent, with 8 of 492 patients (1.6%) in the 0.8 mg group and no patients in the 0.4 mg or placebo groups discontinuing treatment due to abnormal ejaculation.
Laboratory Tests
No laboratory test interactions with FLOMAX capsules are known. Treatment with FLOMAX capsules for up to 12 months had no significant effect on prostate-specific antigen (PSA).
Strong and Moderate Inhibitors of CYP3A4 or CYP2D6
Tamsulosin is extensively metabolized, mainly by CYP3A4 and CYP2D6.
Concomitant treatment with ketoconazole (a strong inhibitor of CYP3A4) resulted in an increase in the C
max 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
Clinical Pharmacology (12.3)]
.
Concomitant treatment with paroxetine (a strong inhibitor of CYP2D6) resulted in an increase in the C
max and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively
[see
Warnings and Precautions (5.2) and
Clinical Pharmacology (12.3)]
. A similar increase in exposure is expected in CYP2D6 poor metabolizers (PM) as compared to extensive metabolizers (EM). Since CYP2D6 PMs cannot be readily identified and the potential for significant increase in tamsulosin exposure exists when FLOMAX 0.4 mg is coadministered with strong CYP3A4 inhibitors in CYP2D6 PMs, FLOMAX capsules 0.4 mg should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole)
[see
Warnings and Precautions (5.2) and
Clinical Pharmacology (12.3)]
.
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
Clinical Pharmacology (12.3)]
.
The effects of coadministration 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 coadministered with a combination of both CYP3A4 and CYP2D6 inhibitors
[see
Warnings and Precautions (5.2) and
Clinical Pharmacology (12.3)]
.
Cimetidine
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
Clinical Pharmacology (12.3)]
.
Risk Summary
FLOMAX is not indicated for use in women. There are no adequate data on the developmental risk associated with the use of FLOMAX in pregnant women. No adverse developmental effects were observed in animal studies in which tamsulosin hydrochloride was administered to rats or rabbits during the period of organogenesis (GD 7 to 17 in the rat and GD 6 to 18 in the rabbit)
[see
Data].
In the U.S. general population, the estimated background risk of major birth defects and of miscarriage in clinically recognized pregnancies is 2%–4% and 15%–20%, respectively.
Data
Administration of tamsulosin hydrochloride to pregnant female rats during the period of organogenesis at dose levels up to approximately 50 times the human therapeutic AUC exposure (300 mg/kg/day) revealed no evidence of harm to the fetus. Administration of tamsulosin hydrochloride to pregnant rabbits during the period of organogenesis at dose levels up to 50 mg/kg/day produced no evidence of fetal harm.
Data
Oral administration of radiolabeled tamsulosin hydrochloride to rats demonstrated that tamsulosin hydrochloride and/or its metabolites are excreted into the milk of rats.
Infertility
Males
Abnormal ejaculation including ejaculation failure, ejaculation disorder, retrograde ejaculation, and ejaculation decrease has been associated with FLOMAX
[see
Adverse Reactions (6.1)].
Studies in rats revealed significantly reduced fertility in males considered to be due to impairment of ejaculation, which was reversible
[see
Nonclinical Toxicology (13.1)].
Females
FLOMAX is not indicated for use in women. Female fertility in rats was significantly reduced, considered to be due to impairment of fertilization
[see
Nonclinical Toxicology (13.1)].
Absorption
Absorption of tamsulosin hydrochloride from FLOMAX capsules 0.4 mg is essentially complete (>90%) following oral administration under fasting conditions. Tamsulosin hydrochloride exhibits linear kinetics following single and multiple dosing, with achievement of steady-state concentrations by the fifth day of once-a-day dosing.
Effect of Food
The time to maximum concentration (T
max) is reached by 4 to 5 hours under fasting conditions and by 6 to 7 hours when FLOMAX capsules are administered with food. Taking FLOMAX capsules under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak concentrations (C
max) compared to fed conditions (Figure 1).
Figure 1: Mean Plasma Tamsulosin Hydrochloride Concentrations Following Single-Dose Administration of FLOMAX Capsules 0.4 mg Under Fasted and Fed Conditions (n=8)
The effects of food on the pharmacokinetics of tamsulosin hydrochloride are consistent regardless of whether a FLOMAX capsule is taken with a light breakfast or a high-fat breakfast (Table 2).
Table 2: Mean (± S.D.) Pharmacokinetic Parameters Following FLOMAX Capsules 0.4 mg Once Daily or 0.8 mg Once Daily with a Light Breakfast, High-Fat Breakfast or Fasted| Pharmacokinetic Parameter | 0.4 mg QD to healthy volunteers; n=23
(age range 18–32 years)
| 0.8 mg QD to healthy volunteers; n=22
(age range 55–75 years)
|
|---|
| Light Breakfast | Fasted | Light Breakfast | High-Fat Breakfast | Fasted |
|---|
C
min = observed minimum concentration
C
max = observed maximum tamsulosin hydrochloride plasma concentration
T
max = median time-to-maximum concentration
T
1/2 = observed half-life
AUC
τ = area under the tamsulosin hydrochloride plasma time curve over the dosing interval
|
| C
min (ng/mL)
| 4.0 ± 2.6 | 3.8 ± 2.5 | 12.3 ± 6.7 | 13.5 ± 7.6 | 13.3 ± 13.3 |
| C
max (ng/mL)
| 10.1 ± 4.8 | 17.1 ± 17.1 | 29.8 ± 10.3 | 29.1 ± 11.0 | 41.6 ± 15.6 |
| C
max/C
min Ratio
| 3.1 ± 1.0 | 5.3 ± 2.2 | 2.7 ± 0.7 | 2.5 ± 0.8 | 3.6 ± 1.1 |
| T
max (hours)
| 6.0 | 4.0 | 7.0 | 6.6 | 5.0 |
| T
1/2 (hours)
| - | - | - | - | 14.9 ± 3.9 |
| AUC
τ (ng∙hr/mL)
| 151 ± 81.5 | 199 ± 94.1 | 440 ± 195 | 449 ± 217 | 557 ± 257 |
Distribution
The mean steady-state apparent volume of distribution of tamsulosin hydrochloride after intravenous administration to 10 healthy male adults was 16 L, which is suggestive of distribution into extracellular fluids in the body.
Tamsulosin hydrochloride is extensively bound to human plasma proteins (94% to 99%), primarily alpha
1 acid glycoprotein (AAG), with linear binding over a wide concentration range (20 to 600 ng/mL). The results of two-way
in vitro studies indicate that the binding of tamsulosin hydrochloride to human plasma proteins is not affected by amitriptyline, diclofenac, glyburide, simvastatin plus simvastatin-hydroxy acid metabolite, warfarin, diazepam, propranolol, trichlormethiazide, or chlormadinone. Likewise, tamsulosin hydrochloride had no effect on the extent of binding of these drugs.
Metabolism
There is no enantiomeric bioconversion from tamsulosin hydrochloride [R(-) isomer] to the S(+) isomer in humans. Tamsulosin hydrochloride is extensively metabolized by cytochrome P450 enzymes in the liver and less than 10% of the dose is excreted in urine unchanged. However, the pharmacokinetic profile of the metabolites in humans has not been established. Tamsulosin is extensively metabolized, mainly by CYP3A4 and CYP2D6 as well as via some minor participation of other CYP isoenzymes. Inhibition of hepatic drug-metabolizing enzymes may lead to increased exposure to tamsulosin
[see
Warnings and Precautions (5.2) and
Drug Interactions (7.1)]
. The metabolites of tamsulosin hydrochloride undergo extensive conjugation to glucuronide or sulfate prior to renal excretion.
Incubations with human liver microsomes showed no evidence of clinically significant metabolic interactions between tamsulosin hydrochloride and amitriptyline, albuterol (beta agonist), glyburide (glibenclamide) and finasteride (5-alpha-reductase inhibitor for treatment of BPH). However, results of the
in vitro testing of the tamsulosin hydrochloride interaction with diclofenac and warfarin were equivocal.
Excretion
On administration of the radiolabeled dose of tamsulosin hydrochloride to 4 healthy volunteers, 97% of the administered radioactivity was recovered, with urine (76%) representing the primary route of excretion compared to feces (21%) over 168 hours.
Following intravenous or oral administration of an immediate-release formulation, the elimination half-life of tamsulosin hydrochloride in plasma ranged from 5 to 7 hours. Because of absorption rate-controlled pharmacokinetics with FLOMAX capsules, the apparent half-life of tamsulosin hydrochloride is approximately 9 to 13 hours in healthy volunteers and 14 to 15 hours in the target population.
Tamsulosin hydrochloride undergoes restrictive clearance in humans, with a relatively low systemic clearance (2.88 L/h).
Specific Populations
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≤ CL
cr <70 mL/min/1.73 m
2) or moderate-severe (10≤ CL
cr <30 mL/min/1.73 m
2) renal impairment and 6 normal subjects (CL
cr >90 mL/min/1.73 m
2). 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 (CL
cr <10 mL/min/1.73 m
2) 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 C
max 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 C
max 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 coadministered with strong CYP3A4 inhibitors in CYP2D6 PMs, FLOMAX capsules 0.4 mg 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 coadministration 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 coadministered 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 coadministered 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 C
max 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)]
.
•
Hypotension
Advise the patient about the possible occurrence of symptoms related to postural hypotension, such as dizziness, when taking FLOMAX capsules, and they should be cautioned about driving, operating machinery, or performing hazardous tasks
[see
Warnings and Precautions (5.1)]
.
•
Drug Interactions
Advise the patient that FLOMAX should not be used in combination with strong inhibitors of CYP3A4
[see
Warnings and Precautions (5.2) and
Drug Interactions (7.1)]
.
•
Priapism
Advise the patient about the possibility of priapism as a result of treatment with FLOMAX capsules and other similar medications. Patients should be informed that this reaction is extremely rare, but if not brought to immediate medical attention, can lead to permanent erectile dysfunction (impotence)
[see
Warnings and Precautions (5.3)]
.
•
Screening for Prostate Cancer
Prostate cancer and BPH frequently coexist; therefore, screen patients for the presence of prostate cancer prior to treatment with FLOMAX capsules and at regular intervals afterwards
[see
Warnings and Precautions (5.4)].
•
Intraoperative Floppy Iris Syndrome
Advise the patient when considering cataract or glaucoma surgery to tell their ophthalmologist that they have taken FLOMAX capsules
[see
Warnings and Precautions (5.5)]
.
•
Administration
Advise the patient that FLOMAX capsules should not be crushed, chewed or opened
[see
Dosage and Administration (2)]
.
FDA-approved Patient Labeling
Patient labeling is provided as a tear-off leaflet at the end of this prescribing information.
Distributed by:
sanofi-aventis U.S. LLC
Bridgewater, NJ 08807
A SANOFI COMPANY
Flomax is a registered trademark of and licensed from:
Astellas Pharma Inc.
Tokyo 103-8411, JAPAN
© 2019. All rights reserved.