Tamplus RX: Combination Medication for Benign Prostatic Hyperplasia
Tamplus RX is a combination medication containing tamsulosin (an alpha-1 adrenergic receptor blocker) used to treat lower urinary tract symptoms associated with benign prostatic hyperplasia (BPH).
Mechanism of Action
Tamsulosin is a selective alpha-1A and alpha-1D adrenoceptor antagonist that relaxes smooth muscle in the prostate, prostatic capsule, prostatic urethra, and bladder, resulting in improved urinary flow and reduced symptoms 1, 2
The drug works by blocking alpha-1 receptors that predominate in these tissues, leading to decreased urethral resistance and improved bladder emptying 3
Clinical Efficacy
Tamsulosin 0.4 mg daily increases maximum urine flow (Qmax) by 1.4 to 1.79 mL/sec from baseline and improves total symptom scores by 3.0 to 5.2 points compared to placebo improvements of only 1.9 to 3.2 points 1
The therapeutic effect manifests within 4-8 weeks of starting treatment, with efficacy maintained for up to 4-6 years in long-term studies 1, 2
Tamsulosin is effective across the spectrum of mild to severe lower urinary tract symptoms, in elderly patients, those with diabetes mellitus, and does not interfere with antihypertensive medications including nifedipine, enalapril, or atenolol 1, 2
Dosing and Administration
The standard dose is 0.4 mg once daily in a modified-release formulation, with no need for initial dose titration 2, 3
A higher dose of 0.8 mg daily may be used, though the 0.4 mg dose represents the ceiling for most therapeutic benefits 1
The oral controlled absorption system (OCAS) formulation has food-independent absorption, while the modified-release formulation's absorption is affected by concomitant food intake 4
Pharmacokinetics
Oral bioavailability of the modified-release formulation in the fasted state approaches 100% 4
The drug exhibits high plasma-protein binding, largely to alpha-1-acid glycoprotein, and is metabolized primarily by CYP3A4 and CYP2D6 4
Only 8.7-15% of an oral dose is excreted renally as unchanged drug 4
Neither renal impairment nor mild to moderate hepatic impairment necessitates dose adjustment 4
Adverse Effects Profile
The most common adverse effects are abnormal ejaculation (4.5-14% of patients), dizziness, rhinitis, headache, and asthenia 1, 2, 3
The overall incidence of orthostatic symptoms is only 1.4%, and tamsulosin does not cause clinically significant changes in blood pressure or first-dose syncope 1, 3
Retrograde or delayed ejaculation occurs in 4.5-14% of patients but rarely requires treatment discontinuation 3
Postural hypotension and palpitations occur in only 1-2% of patients 2
Drug Interactions
Concomitant exposure to potent CYP3A4 inhibitors can more than double tamsulosin exposure, requiring caution with these combinations 4
Tamsulosin does not require dosage modification when used with nifedipine, enalapril, atenolol, furosemide, or digoxin, and hypotension has not been reported with these combinations 3
Comparative Advantages
Tamsulosin offers significant advantages over older non-selective alpha-blockers: single daily dosing without titration, rapid onset of action, and minimal hypotensive effects 2, 3
Tamsulosin 0.4 mg daily demonstrated similar efficacy to alfuzosin 2.5 mg three times daily but with less tendency to cause hypotensive effects 2
The drug has less effect on blood pressure than alfuzosin or terazosin 1
Off-Label Use in Women
Tamsulosin has been used off-label for lower urinary tract symptoms in women, with meta-analysis showing improved International Prostate Symptom Score (IPSS) by 4.08 points compared to placebo 5
The drug improved storage symptoms, voiding symptoms, quality-of-life scores, average flow rate, and post-void residual volume in female patients 5
However, the long-term safety profile in women remains unknown and requires further well-conducted trials 5