Cycrin (Medroxyprogesterone Acetate): Comprehensive Product Information for Australia
Basic Product Information
| International Non-proprietary Name (INN) | Medroxyprogesterone Acetate |
| Australia Brand Names | Cycrin, Provera®, others |
| ATC Code | G03DA02 |
| Available Forms & Strengths | Tablets: 2.5 mg, 5 mg, 10 mg; Injectable forms are also available for specific indications |
| Manufacturers | Pfizer Australia Pty Ltd, Apotex, and other approved manufacturers |
| Prescription Status | Prescription only (Schedule 4: Prescription Medicine) |
Mechanism of Action
- For Patients: Medroxyprogesterone acetate acts like the natural hormone progesterone. It helps regulate menstrual cycles and can reduce abnormal uterine bleeding. It also plays a key role in hormone replacement therapy and certain cancer treatments.
- For Specialists: Medroxyprogesterone acetate binds to progesterone receptors, inhibiting gonadotrophin secretion (LH and FSH) from the pituitary gland, inducing endometrial secretory transformation, and producing antioestrogenic effects on the endometrium. At higher doses, it’s antigonadotropic, suppressing the pituitary-gonadal axis.
Pharmacokinetics
- Absorption: Well absorbed orally, peak plasma concentration in 2-4 hours after ingestion.
- Metabolism: Extensive hepatic metabolism, primarily via CYP3A4 enzymes.
- Elimination: Mostly renally excreted as metabolites; small proportion via faeces.
- Duration of Action: Tablets have a half-life of approximately 12-17 hours, suitable for once daily dosing.
Use in Everyday Life and Best Practices (Australia Context)
- Cycrin is usually taken once daily, at the same time each day for best results. It is prescribed for menstrual irregularities, management of abnormal uterine bleeding, part of hormone replacement therapy (HRT) in postmenopausal women, and for some specialist cancer treatments.
- Follow your doctor’s instructions carefully. Never change your dose or dosing schedule without consulting your prescriber or pharmacist.
- In Australia, Medroxyprogesterone is not used as a routine contraceptive tablet (see alternative options below).
Dosing in the Morning vs Evening
- Morning Use: May help reduce insomnia or vivid dreams, as some people experience mild stimulant effects. Early dosing can also make it easier to remember, aligning with other morning medications or routines.
- Evening Use: May be recommended if daytime drowsiness is an issue. However, some may experience sleep disturbances. Stick to the same time daily for best results, using reminders or pill organizers.
- Tip: Choose a time you can consistently remember and avoid missing doses. Discuss preference and side effect profile with your pharmacist or GP.
Taking with Food or on an Empty Stomach
- Cycrin tablets can be taken with or without food. Taking with food may ease mild stomach upset.
- There is no significant food effect on drug absorption.
- Australian dietary habits (heavy breakfast, light lunch or vice versa) do not require special adjustments.
Interaction Warnings
| Item | Interaction Effect | Advice |
| Alcohol | Generally safe; may increase drowsiness in rare cases | Limit consumption until you know your response |
| CYP3A4 inducers (e.g. certain anticonvulsants) | May reduce effectiveness of Cycrin | Consult your doctor if beginning new medicines |
| St John’s Wort | Can lower drug levels and effectiveness | Avoid use together; ask your pharmacist for alternatives |
| Anticoagulants | Possible increased clotting risk | Monitor closely with your doctor |
| Other hormone therapies | May interact or require dose changes | Inform all clinicians of your full medication list |
Indications for Use
| Indication | Status in Australia | Notes |
| Abnormal uterine bleeding | Approved | For dysfunctional or irregular bleeding |
| Secondary amenorrhoea | Approved | Restores periods |
| Hormone replacement therapy (HRT) | Approved | Added to oestrogen to protect endometrium |
| Endometrial hyperplasia prevention | Approved | Used in postmenopausal women on oestrogen |
| Advanced breast/endometrial/prostate cancer | Approved | Higher dose regimes |
| Off-label uses (e.g. endometriosis) | Used off-label | Discuss risks/benefits with your specialist |
Dosing According to Clinical Indications
| Condition | Adult Dose | Pediatric/Elderly Adjustment |
| Abnormal uterine bleeding | 5-10 mg orally once daily for 5–10 days/cycle | Not routinely used in paediatrics; no elderly-specific dose but monitor renal/hepatic function |
| Secondary amenorrhoea | 5-10 mg orally once daily for 5–10 days/month | — |
| HRT (with oestrogen) | 2.5 or 5 mg daily continuously OR 5-10 mg daily for 12–14 days/cycle | Adjust if significant renal/hepatic disease. Monitor elderly more closely for side effects |
| Cancer palliative therapy | 200–1000 mg daily (injectable forms available) | — |
Always follow your doctor’s individualised dosing instructions. Tablets should be swallowed whole with water.
Safety Profile and Side Effects
| Common Side Effects | Rare/Serious Side Effects | Warnings |
- Breast tenderness
- Headache
- Abdominal discomfort
- Weight changes
- Mood changes/irritability
- Mild nausea
| - Severe allergic reaction
- Deep vein thrombosis (very rare)
- Liver function changes
- Vision disturbances
- Severe depression
| - Avoid use in undiagnosed vaginal bleeding
- Care if history of thrombosis, stroke, or active cancer (except cancer indication)
- Check interactions with other hormone therapies
|
Guidelines for Proper Use (Australian Conditions)
- Begin your course exactly as prescribed; stick to the regimen and complete the full course even if symptoms improve early.
- If you miss a dose, take it as soon as possible; skip if it’s almost time for the next dose. Never double up.
- Store at room temperature, away from excess heat or moisture – typical Australian household conditions are suitable.
- Do not share your medication; keep it out of reach of children and pets.
- Have regular check-ups to monitor for side effects, especially if used long term.
- Report any unexpected or severe side effects to your doctor or pharmacist promptly.
Alternative Treatment Options
- Dydrogesterone (Duphaston): Another oral progestin; lower androgenic effect; similar efficacy for cycle regulation
- Natural progesterone (Prometrium): Plant-derived; sometimes preferred for HRT due to lower VTE risk
- Levonorgestrel IUD (Mirena): Intrauterine device for endometrial protection or heavy bleeding; fewer systemic effects, long-acting
- Tranexamic acid: For heavy menstrual bleeding not due to hormone imbalance
- Combined oral contraceptives: Not suitable for all, but may manage bleeding/irregularities in some cases
Most alternatives are available on the PBS (Pharmaceutical Benefits Scheme) in Australia. Eligibility, co-payments, and suitability should be discussed with your healthcare team.
Legal, Registration, and Reimbursement Status in Australia
- Cycrin (Medroxyprogesterone acetate) is registered with the Therapeutic Goods Administration (TGA) and is listed on the Pharmaceutical Benefits Scheme (PBS) for approved indications.
- It is a Schedule 4 prescription-only medicine, dispensed only on a valid script from your GP or specialist.
- Reimbursement/co-payment is available under PBS for specific clinical indications (e.g. some HRT uses, advanced cancer).
- Pharmacists and clinics across Australia hold information on local supply options and current PBS status.
Latest Research & Clinical Guidance (2022–2025)
- Recent Australian guidelines (Royal Australian and New Zealand College of Obstetricians and Gynaecologists, 2023) reaffirmed Cycrin’s role in HRT, prevention of endometrial hyperplasia, and management of abnormal bleeding.
- Current evidence (2022–2024) supports the safety of low-dose oral medroxyprogesterone for endometrial protection in postmenopausal women (see Menopause Society of Australia position statements).
- Ongoing studies are reviewing the vascular risks (e.g. VTE, stroke) with high-dose or long-term use, especially in elderly women. Discuss individual risks with your doctor.
- References: Therapeutic Guidelines (eTG complete, 2024); Australian Menopause Society, Position Statements 2022–2024; TGA Product Information.
Availability, Pack Sizes, & Delivery Information
| Pack Size | Approximate PBS Price (2024) | Typical Supply | Delivery (Regional/Metro Australia) |
| 30 tablets | $12.40 (concessional: $7.30) | 1 month | 1–4 business days (metro); 3–6 business days (regional/remote) |
| 100 tablets | $38.20 | 3 months | 1–4 business days (metro); 3–6 business days (regional/remote) |
Same-day or express delivery may be available in major cities including Sydney, Melbourne, Brisbane, and Perth; check with your pharmacy.
FAQs – Your Questions Answered
- How long does Cycrin take to start working?
Many women notice changes (e.g. improvement in bleeding patterns) within the first week. Menstrual restoration may take one full cycle. Discuss your results with your healthcare provider after 1–2 months. - Can I drive or use heavy machinery while taking Cycrin?
Most people can, but if you feel dizzy or unusually sleepy after your dose, wait until you feel well before driving or operating machinery. These symptoms are uncommon. - What should I do if I miss a dose?
Take the missed dose as soon as you remember unless it’s almost time for your next dose – then skip. Never double your dose to compensate. - Can I use Cycrin for contraception?
Oral Cycrin is not a contraceptive. Consult your doctor for appropriate contraceptive options available in Australia. - Is it safe with my other medicines?
Most medicines are safe, but always inform your doctor and pharmacist of all prescription, over-the-counter, and herbal products you use.
Need more information? For any concerns or further questions, contact your local pharmacist, GP, or the National Prescribing Service (NPS) MedicineWise helpline at 1300 633 424.
