Consumer medicine information

1. Why am I taking DOUBLUTS?

DOUBLUTS contains the active ingredients dutasteride and tamsulosin hydrochloride. DOUBLUTS is used in men who have benign prostatic hyperplasia (BPH).
For more information, see Section 1. Why am I taking DOUBLUTS? in the full CMI.

2. What should I know before I take DOUBLUTS?

Do not use if you have ever had an allergic reaction to DOUBLUTS, any other 5 alpha reductase inhibitors or any of the ingredients listed at the end of the CMI.
Talk to your doctor if you have any other medical conditions or take any other medicines. Talk to your doctor if your partner is pregnant or plans to become pregnant or is breastfeeding.
For more information, see Section 2. What should I know before I take DOUBLUTS? in the full CMI.

3. What if I am taking other medicines?

Some medicines may interfere with DOUBLUTS and affect how it works.
A list of these medicines is in Section 3. What if I am taking other medicines? in the full CMI.

4. How do I take DOUBLUTS?

• The usual dosage is one capsule once per day.

• Take your medicine approximately 30 minutes after the same meal each day. Do not take DOUBLUTS on an empty stomach.

5. What should I know while taking DOUBLUTS?

6. Are there any side effects?

Side effects which have been reported include impotence (an inability to maintain an erection), decrease in libido (sex drive), difficulty with ejaculation, breast swelling or tenderness, difficulty in sleeping (insomnia), dizziness, constipation, diarrhoea, vomiting, a fast heart beat, feeling weak or a loss of strength, low blood pressure upon standing up, itchy, blocked or runny nose and allergic reactions.
For more information, including what to do if you have any side effects, see Section 6. Are there any side effects? in the full CMI.

1 Name of Medicine

Dutasteride/tamsulosin hydrochloride.

2 Qualitative and Quantitative Composition

Each capsule contains 500 micrograms of dutasteride and 400 micrograms of tamsulosin hydrochloride.
Dutasteride. Dutasteride is a white to pale yellow powder. It is practically insoluble in water, and soluble in organic solvents, dimethyl sulfoxide, acetone, methanol, ethanol and ispropanol.
Tamsulosin Hydrochloride. White or almost white crystalline powder. It is sparingly soluble in water, and slightly soluble in the following solvents; Acetone, Ethanol, Ethyl acetate and Methanol.
The pKa values for tamsulosin are as follows: pKa1 = 8.4 (secondary amine) and pKa2 = 10.7 (sulphonamide). The partition coefficient is clogP = 2.2 (calculated using Property Calculator 4.7)
Excipients with known effect. Lecithin.
For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Doubluts capsules (dutasteride 500 micrograms / tamsulosin hydrochloride 400 micrograms): oblong, hard-shell capsules with a brown body and an orange cap imprinted with GS 7CZ in black ink [each containing one oblong, opaque, dull yellow dutasteride soft gelatin capsule (containing 500 micrograms of dutasteride) and white to off-white tamsulosin hydrochloride pellets (containing 400 micrograms of tamsulosin hydrochloride)].

4 Clinical Particulars

4.9 Overdose

No data are available with regard to overdosage of Doubluts. The following statements reflect the information available on the individual components.
Dutasteride. In volunteer studies single doses of dutasteride up to 40 mg/day (80 times the therapeutic dose) for 7 days have been administered without significant safety concerns. In clinical studies doses of 5 mg daily have been administered to patients for 6 months with no additional adverse effects to those seen at therapeutic doses of 500 microgram.
There is no specific antidote for dutasteride therefore, in cases of suspected overdosage symptomatic and supportive treatment should be given as appropriate.
Tamsulosin. In case of acute hypotension occurring after overdosage with tamsulosin hydrochloride cardiovascular support should be given. Restoration of blood pressure and normalization of heart rate may be accomplished by lying the patient down. If this is inadequate, administration of volume expanders and if necessary vasopressors should then be used and renal function should be monitored and supported as needed. Laboratory data indicate that tamsulosin hydrochloride is 94% to 99% protein bound; therefore, dialysis is unlikely to be of benefit in removing tamsulosin from the body.
For information on the management of overdose, contact the Poisons Information Centre on 13 11 26 (Australia).

5 Pharmacological Properties

5.3 Preclinical Safety Data

Genotoxicity. Dutasteride and tamsulosin hydrochloride showed no evidence of genotoxicity in a wide range of in vitro and in vivo tests.
Carcinogenicity. Dutasteride. In a carcinogenicity study in rats, dutasteride produced an increase in benign interstitial cell tumours in the testis at the high dose (158-fold clinical exposure). However, the endocrine mechanisms believed to be involved in the production of interstitial cell hyperplasia and adenomas in the rat are not relevant to humans. There were no clinically relevant effects on tumour profile in a carcinogenicity study in mice.
Tamsulosin. Oral (dietary) administration of tamsulosin for up to 2 years in rats and mice was associated with an increased incidence of pituitary adenoma, mammary gland hyperplasia, mammary gland fibroadenoma and (in mice only) mammary gland adenocarcinoma. These effects occurred at plasma tamsulosin concentrations (AUC) up to 10 times lower than those expected in men undergoing treatment with tamsulosin, but they were observed only in female animals and are probably due to the hyperprolactinaemic effect of tamsulosin. It is not known if tamsulosin elevates prolactin during prolonged administration in humans. The relevance for human risk of the findings of prolactin mediated endocrine tumours in female rodents is unknown.

6 Pharmaceutical Particulars

6.7 Physicochemical Properties

Chemical structure.
https://stagingapi.mims.com/au/public/v2/images/fullchemgif/CSDUTAST.gif https://stagingapi.mims.com/au/public/v2/images/fullchemgif/CSTAMHYD.gif Dutasteride. Chemical name: 4-azaandrost-1-ene-17-carboxamide, N-(2,5- bis (trifluoromethyl)phenyl)-3-oxo-, (5alpha, 17beta).
Molecular formula: C₂₇H₃₀F₆N₂O₂.
Tamsulosin hydrochloride. Chemical name: (-)-(R)-5-[2-[[2-(2-ethoxyphenoxy) ethyl] amino]propyl]-2-methoxybenzenesulfonamide, monohydrochloride.
Molecular formula: C₂₀H₂₈N₂O₅S.HCl.
CAS number. Dutasteride. 164656-23-9.
Tamsulosin hydrochloride. 106463-17-6.

7 Medicine Schedule (Poisons Standard)

Schedule 4 - Prescription Only Medicine.