Dutasteride & Tamsulosin combination capsules are indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate.
BPH/ Urinary retention/ Urinary incontinence
Tamsulosin & Dutasteride is a combination of two drugs with complementary mechanisms of action to improve symptoms in patients with Benign Prostatic Hyperplasia (BPH). Tamsulosin Hydrochloride, an antagonist of alpha1A-adrenoreceptors and Dutasteride, a dual 5 alpha reductase inhibitor (5ARI). Treatment of BPH with alpha1-adrenoreceptor blocking agents and 5ARIs results in an improvement in urine flow rate and a reduction in symptoms of BPH.
Tamsulosin: An alpha1-adrenoreceptor blocking agent that affects the dynamic component of BPH by inhibiting alpha1-adrenoreceptors in the stromal prostatic smooth muscle and bladder neck. Blockade of these adrenoreceptors can cause smooth muscles in the bladder neck and prostate to relax. Specifically, Tamsulosin exhibits selectivity for both alpha 1A and alpha 1D receptors over the alpha1B-adrenoreceptor subtype. These three adrenoreceptor subtypes have a distinct distribution pattern in human tissue. Whereas approximately 70% of the alpha1-receptors in human prostate are of the alpha 1A subtype, the human bladder contains predominantly the alpha 1D subtype while blood vessels express predominantly alpha 1B subtype. It is further believed that blockade of the alpha 1D subtypes in the human obstructed bladder may be responsible for reducing detrusor overactivity and subsequent relief of storage symptoms.
Dutasteride: A synthetic 4-azasteriod compound is a competitive and specific inhibitor of both Type I and Type II 5 alpha-reductase isoenzymes that affects the static component of BPH by inhibiting the conversion of Testosterone to Dihydrotestosterone (DHT) by the enzyme 5 alpha-reductase. 5 alpha-reductase exists as 2 isoforms, Type I and Type II, both of which are present in the prostate. It has been observed that compared to normal tissue, the expression of both isoenzymes are increased in BPH tissue. Dissociation from this complex has been evaluated under in vitro and in vivo conditions and is extremely slow. Dutasteride lowers DHT levels and leads to a reduction in prostatic volume, thereby treating an underlying cause of BPH. Dutasteride does not bind to the human androgen receptor.
The recommended dosage is 1 capsule (0.5 mg Dutasteride and 0.4 mg Tamsulosin Hydrochloride) taken once daily approximately 30 minutes after the same meal each day. The capsules should be swallowed whole and not chewed or opened. Contact with the contents of the capsule may result in irritation of the oropharyngeal mucosa.
There have been no drug interaction studies for Dutasteride-Tamsulosin combination.
Effects of other drugs on the pharmacokinetics of Dutasteride: Use together with CYP3A4 and/or P-glycoprotein-inhibitors: Dutasteride is mainly eliminated via metabolism. In vitro studies indicate that this metabolism is catalysed by CYP3A4 and CYP3A5. No formal interaction studies have been performed with potent CYP3A4 inhibitors. However, in a population pharmacokinetic study, Dutasteride serum concentrations were on average 1.6 to 1.8 times greater, respectively, in a small number of patients treated concurrently with verapamil or diltiazem (moderate inhibitors of CYP3A4 and inhibitors of P-glycoprotein) than in other patients. Long-term combination of Dutasteride with drugs that are potent inhibitors of the enzyme CYP3A4 (e.g. ritonavir, indinavir, nefazodone, itraconazole, ketoconazole administered orally) may increase serum concentrations of Dutasteride. Further inhibition of 5-alpha reductase at increased Dutasteride exposure, is not likely. However, a reduction of the Dutasteride dosing frequency can be considered if side effects are noted. It should be noted that in the case of enzyme inhibition, the long half-life may be further prolonged and it can take more than 6 months of concurrent therapy before a new steady state is reached. Administration of 12 g cholestyramine one hour after a 5 mg single dose of Dutasteride did not affect the pharmacokinetics of Dutasteride.
Effects of Dutasteride on the pharmacokinetics of other drugs: In a small study (N=24) of two weeks duration in healthy men, Dutasteride (0.5 mg daily) had no effect on the pharmacokinetics of Tamsulosin or terazosin. There was also no indication of a pharmacodynamic interaction in this study. Dutasteride has no effect on the pharmacokinetics of warfarin or digoxin. This indicates that Dutasteride does not inhibit/induce CYP2C9 or the transporter P-glycoprotein. In vitro interaction studies indicate that Dutasteride does not inhibit the enzymes CYP1A2, CYP2D6, CYP2C9, CYP2C19 or CYP3A4. Tamsulosin: Concomitant administration of Tamsulosin Hydrochloride with drugs which can reduce blood pressure, including anaesthetic agents, PDE5 inhibitors and other alpha-1 adrenergic blockers could lead to enhanced hypotensive effects. Tamsulosin-Dutasteride should not be used in combination with other alpha-1 adrenergic blockers. Concomitant administration of Tamsulosin Hydrochloride (0.4 mg) and cimetidine (400 mg every six hours for six days) resulted in a decrease in the clearance (26%) and an increase in the AUC (44%) of Tamsulosin Hydrochloride. Caution should be used when Tamsulosin-Dutasteride is used in combination with cimetidine. A definitive drug-drug interaction study between Tamsulosin Hydrochloride and warfarin has not been conducted. Results from limited in vitro and in vivo studies are inconclusive. Caution should be exercised with concomitant administration of warfarin and Tamsulosin Hydrochloride. No interactions have been seen when Tamsulosin Hydrochloride was given concomitantly with either atenolol, enalapril, nifedipine or theophylline. Concomitant furosemide brings about a fall in plasma levels of Tamsulosin, but as levels remain within the normal range posology need not be adjusted. In vitro neither diazepam nor propranolol, trichlormethiazide, chlormadinon, amitryptyline, diclofenac, glibenclamide and simvastatin change the free fraction of Tamsulosin in human plasma. Neither does Tamsulosin change the free fractions of diazepam, propranolol, trichlormethiazide, and chlormadinon. No interactions at the level of hepatic metabolism have been seen during in vitro studies with liver microsomal fractions, involving amitriptyline, salbutamol and glibenclamide. Diclofenac however, may increase the elimination rate of Tamsulosin.
Tamsulosin-Dutasteride combination is contra-indicated in women and children and adolescents, patients with hypersensitivity to Dutasteride, other 5-alpha reductase inhibitors, Tamsulosin (including Tamsulosin- induced angio-edema), soya, peanut or any of other the excipients, patients with a history of orthostatic hypotension and patients with severe hepatic impairment. Dutasteride-Tamsulosin combination capsules are used with caution because it- Can occur orthostatic hypotension and syncope Reduces serum prostate-specific antigen (PSA) concentration by approximately 50% Do not use with strong inhibitors of cytochrome P450 (CYP) 3A4 (e.g. Ketoconazole) Exercise caution with concomitant use of PDE-5 inhibitors, as this may increase the risk of hypotension Drugs that contain Dutasteride, may increase the risk of high-grade prostate cancer Women who are pregnant or could become pregnant should not handle due to potential risk to a male fetus Advise patients about the possibility and seriousness of priapism Patients should not donate blood until 6 months after their last dose Intraoperative Floppy Iris Syndrome has been observed during cataract surgery after alpha adrenergic antagonist exposure Exercise caution with concomitant use of Warfarin
Impotence, decreased libido, breast disorders (including breast enlargement and tenderness), ejaculation disorders, erectile dysfunction and dizziness etc. may occur. Again, infection, asthenia, back pain, chest pain, somnolence, insomnia, rhinitis, pharyngitis, cough, sinusitis, and diarrhea etc. may occur.
Pregnancy: As with other 5 alpha reductase inhibitors, Dutasteride inhibits the conversion of testosterone to dihydrotestosterone and may, if administered to a woman carrying a male foetus, inhibit the development of the external genitalia of the foetus. Small amounts of Dutasteride have been recovered from the semen in subjects receiving Dutasteride. It is not known whether a male foetus will be adversely affected if his mother is exposed to the semen of a patient being treated with Dutasteride. As with all 5 alpha reductase inhibitors, when the patient$#$#$#$s partner is or may potentially be pregnant it is recommended that the patient avoids exposure of his partner to semen by use of a condom. Administration of Tamsulosin Hydrochloride to pregnant female rats and rabbits showed no evidence of foetal harm. Lactation: It is not known whether Tamsulosin or Dutasteride are excreted in human milk.
No data are available with regard to over dosage of Tamsulosin-Dutasteride combination. The following statements reflect the information available on the individual components.
Dutasteride: In volunteer studies, single daily doses of Dutasteride up to 40 mg/day (80 times the therapeutic dose) have been administered for 7 days without significant safety concerns. In clinical studies, doses of 5 mg daily have been administered to subjects for 6 months with no additional adverse effects to those seen at therapeutic doses of 0.5 mg. There is no specific antidote for Dutasteride, therefore, in suspected over dosage symptomatic and supportive treatment should be given as appropriate.
Tamsulosin: Acute overdose with 5 mg Tamsulosin Hydrochloride has been reported. Acute hypotension (systolic blood pressure 70 mm Hg), vomiting and diarrhoea were observed which were treated with fluid replacement and the patient could be discharged the same day. In case of acute hypotension occurring after over dosage cardiovascular support should be given. Blood pressure can be restored and heart rate brought back to normal by lying the patient down. If this does not help then volume expanders, and when necessary, vasopressors could be employed. Renal function should be monitored and general supportive measures applied. Dialysis is unlikely to be of help as Tamsulosin is very highly bound to plasma proteins. Measures, such as emesis, can be taken to impede absorption. When large quantities are involved, gastric lavage can be applied and activated charcoal and an osmotic laxative, such as sodium sulphate, can be administered.
Store in a cool and dry place, protected from light.
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