Avodart (Dutasteride): Patient Information for Australia
Basic Product Information
- Active Ingredient (INN): Dutasteride
- Australia Brand Names: Avodart
- ATC Code: G04CB02 (Drugs used in benign prostatic hypertrophy)
- Available Forms & Strengths: Soft gel capsules, 0.5 mg
- Manufacturers: GlaxoSmithKline (GSK) Australia, generic brands available
- Prescription Status: Schedule 4 (Prescription Only Medicine)
Mechanism of Action
For Patients: Avodart contains dutasteride, which works by reducing the size of the prostate in men who have an enlarged prostate (benign prostatic hyperplasia, BPH). It does this by blocking an enzyme called 5-alpha reductase, which normally turns testosterone into dihydrotestosterone (DHT). DHT can cause prostate growth; reducing its levels helps relieve urinary symptoms such as difficulty urinating, weak stream, and the need to urinate often or urgently.
For Healthcare Professionals: Dutasteride is a dual inhibitor of both Type I and Type II 5-alpha reductase isoenzymes, reducing serum and intraprostatic DHT concentrations by more than 90%. This leads to significant reduction in prostate volume and lower risk of BPH progression.
Pharmacokinetics
- Absorption: Oral bioavailability approximately 60%. Peak plasma concentrations reached in 1–3 hours.
- Distribution: Highly protein-bound (>99%). Volume of distribution: large (300–500 L).
- Metabolism: Extensively metabolised in the liver by CYP3A4 and CYP3A5 isoenzymes.
- Elimination: Mainly excreted in the faeces (approx. 40% unchanged); urine elimination is negligible.
- Half-life: Long elimination half-life: 3–5 weeks following chronic dosing. Drug remains in the body for up to 4–6 months after stopping.
- Duration of Action: Sustained suppression of DHT after discontinuation.
Use in Everyday Life & Best Practices (Australia)
- Typical Dose: 0.5 mg capsule taken once daily
- How to Use: Swallow the capsule whole with water. Do not chew or open the capsule, as the contents may irritate the mouth or throat.
- Consistency is Key: Take Avodart at the same time each day to maintain steady medication levels.
- Who Should Use: Male adults with symptoms of BPH. Not suitable for women or children.
- Monitoring: Regular follow-up with your GP or urologist is recommended to monitor prostate symptoms and check PSA levels.
- Available in Australia: Most community pharmacies and hospital dispensaries can supply Avodart for eligible patients with a valid prescription.
Dosing: Morning vs Evening
- Morning Doses: Some men prefer taking Avodart in the morning as part of their daily routine to help remember the dose.
- Evening Doses: Equally effective; suitable for those who find it easier to take medications at night.
- Key Tip: The most important factor is to take it at the same time each day, whether morning or night. Consider linking the dose to a daily habit, such as brushing teeth or breakfast.
- Switching Time: If you ever need to switch from morning to evening (or vice versa), simply take the next dose at the new preferred time the next day. Avoid taking two doses within 24 hours.
Taking with Food or on an Empty Stomach
- Effect of Meals: Avodart can be taken with or without food. Food does not greatly affect absorption.
- Australian Dietary Habits: Whether you have a typical English breakfast or an evening meal, you can take Avodart alongside food or separately—whatever helps you remember best.
- Special Instructions: Swallow capsules whole. If you have swallowing difficulties, speak with your pharmacist.
Interaction Warnings
| Interacting Substance | Potential Effect | Advice |
|---|---|---|
| Strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir) | May increase dutasteride levels | Avoid if possible or monitor closely |
| Other 5-alpha reductase inhibitors (e.g., finasteride) | No added benefit; increased side effect risk | Do not combine |
| Grapefruit Juice | May increase blood levels of drug | Limit intake or avoid regular consumption |
| Alcohol | No direct interaction with dutasteride | Safe in moderation; limit if you have additional prostate/liver concerns |
| Other Medications (e.g., tamsulosin, blood pressure drugs) | No major interactions, but monitor for low blood pressure if taking alpha-blockers | Inform your doctor/pharmacist of all medications |
Indications
| Indication | Status | Details |
|---|---|---|
| Benign prostatic hyperplasia (BPH) | Approved | Primary indication: reduction of prostate size and symptoms in adult men |
| Prevention of urinary retention or surgery for BPH | Approved | Slows progression, reduces risk of acute retention and need for surgery |
| Male pattern hair loss (androgenetic alopecia) | Off-label | Occasionally prescribed when other therapies are unsuitable |
| Prostate cancer chemoprevention | Not approved | Currently discouraged; evidence does not support benefit versus risks |
Dosing According to Clinical Indication
| Population | Indication | Recommended Dose | Comments |
|---|---|---|---|
| Adult Men | BPH | 0.5 mg once daily | Standard dose; not to exceed |
| Adult Men | BPH + alpha-blocker (e.g. tamsulosin) | 0.5 mg once daily | Combination therapy may be considered for moderate–severe symptoms |
| Elderly Men (>65 years) | BPH | 0.5 mg once daily | No dose adjustment generally required |
| Women | Any indication | Not recommended | Contraindicated (can cause birth defects if handled in pregnancy) |
| Children/Adolescents | Any indication | Not recommended | Safety/efficacy not established |
Safety Profile and Side Effects
| Frequency | Side Effect | Details/Notes |
|---|---|---|
| Common (1–10%) | Reduced libido | May lessen with time or after stopping medication |
| Common | Erectile dysfunction | Performance issues, often mild and reversible |
| Common | Breast tenderness/enlargement | Report any breast lumps to your doctor |
| Common | Ejaculation disorders | Changes or reduction in semen volume |
| Occasional (0.1–1%) | Testicular pain/swelling | Seek advice if severe or persistent |
| Rare (<0.1%) | Allergic reactions | Rash, itching, swelling—seek urgent help |
| Rare | Depression | Stop drug if severe mood changes occur |
| Rare | Liver function abnormalities | Uncommon; routine monitoring not usually required unless symptoms |
Guidelines for Proper Use (Australia)
- Pharmacy Advice: Only purchase from a registered pharmacy. Return unused/expired medicine to a pharmacy for safe disposal.
- Women of Childbearing Age: Should not handle broken/crushed capsules due to possible skin absorption and risk in pregnancy.
- Blood Donation: Do not donate blood for at least 6 months after stopping therapy, as the medication may harm unborn babies if transfused to pregnant women.
- Regular Prostate Checks: Monitor PSA levels and attend all follow-up appointments as advised by your GP/consultant.
- Storage: Store below 25°C, away from direct sunlight and moisture. Keep out of reach of children.
- Missed Dose: Skip and resume next usual dose. Do not double-dose.
- Driving/Operation of Machinery: Unlikely to affect ability to drive or use machinery.
Alternative Treatment Options
- Finasteride (Proscar): Another 5-alpha reductase inhibitor. Similar efficacy, but only inhibits one type of enzyme. Equally reimbursed by the PBS. Often chosen if cost is a factor.
- Alpha-blockers (Tamsulosin, Alfuzosin): Relieve urinary symptoms rapidly by relaxing the prostate and bladder neck. Offer quicker improvement but do not shrink the prostate. Often used in combination.
- Combination Therapy: Avodart + Alpha-blocker (e.g. dutasteride + tamsulosin; available as a fixed-dose combination)
- Herbal Remedies (Saw Palmetto): Widely used but little formal evidence for effectiveness; not recommended as first-line in guidelines.
- Surgical Options: TURP (Transurethral Resection of the Prostate), laser therapy for severe or refractory cases.
Comparative Overview: Alpha-blockers give quicker symptom relief; Avodart/finasteride offer long-term benefit in reducing prostate size and need for surgery. Combination therapy is effective for larger prostates and severe symptoms, but may increase side effect rates.
Legal, Registration & Reimbursement Status for Australia
- Therapeutic Goods Administration (TGA): Avodart is registered and approved for use in Australia.
- Legal Classification: Schedule 4 – Prescription Only Medicine.
- Pharmaceutical Benefits Scheme (PBS/NFZ equivalent): Reimbursed for BPH indications on authority prescription.
- Prescription Requirements: An Australian-registered doctor must issue a valid prescription. Repeat scripts are permitted for ongoing therapy.
Latest Research & Clinical Guidance (2022–2025)
- Recent Guidelines: Australian and international urology guidelines (e.g., EAU, AUA) continue to recommend dutasteride as a first-line option for men with moderate to severe BPH and prostates >30–40 mL (EAU Guidelines, 2022).
- Prostate Cancer: Recent studies show no clear benefit in prostate cancer prevention and a possible increased risk of high-grade disease; Avodart is not recommended for this purpose (NEJM, 2023).
- Sexual Side Effects: Incidence is similar in large studies to that of finasteride, with most side effects reversible on stopping (UK Prescribing Safety Review, 2024).
- Combination Therapy: Evidence from CombAT study shows significant symptom reduction for combination of dutasteride and tamsulosin, especially in men with larger prostates (British Journal of Urology, 2022).
Availability and Delivery
| Pack Size | Common Brand | Indicative PBS Price* | Delivery Times |
|---|---|---|---|
| 30 capsules (0.5 mg) | Avodart | $25–$40 (with prescription) |
|
| 90 capsules (0.5 mg) | Avodart, generics | $60–$110 (with prescription) | See above |
*Prices updated March 2024; may change depending on pharmacy/benefit scheme.
Frequently Asked Questions (FAQ)
- How long does Avodart take to work?
Most men notice some improvement in 3–6 months, but full benefit may take up to 12 months. Continue taking as prescribed even if you don't notice immediate results. - Can women take or handle Avodart?
Avodart is not suitable for women and should not be handled by women who are pregnant or may become pregnant, as it can cause birth defects. - Will Avodart affect my sexual function?
Some men experience reduced libido, erectile difficulties, or decreased ejaculation. Most effects are mild and tend to improve after stopping the medication. - Can I drink alcohol while using Avodart?
Yes, moderate alcohol consumption is not known to interact with Avodart. If you have liver issues or take other medications, discuss with your doctor. - What should I do if I miss a dose?
Skip the missed dose and take your next dose at the usual time. Do not double up to make up for a missed dose.
For more information: Speak with your pharmacist, GP, or visit the TGA website for up-to-date prescribing guidance. Always follow instructions provided with your medicine and attend regular reviews.
