WHAT IS THIS MEDICINE AND WHAT IS IT USED FOR?
Relupros contains relugolix, the first oral gonadotrophin-releasing
hormone (GnRH) receptor antagonist approved for advanced prostate cancer.
Prostate cancer cells are typically fuelled by the male hormone testosterone.
Relugolix works by blocking GnRH receptors in the pituitary gland, which
switches off the signalling cascade that triggers testosterone production —
rapidly lowering testosterone to castrate levels (very low levels that starve
the cancer).
Unlike older GnRH agonists (such as leuprolide/Lupron, goserelin/Zoladex,
or triptorelin), which cause an initial 'testosterone flare' (a temporary spike
in testosterone) before suppressing it, relugolix works as an antagonist —
blocking the receptor rather than stimulating it — so testosterone drops
immediately without any flare. This means no initial anti-androgen cover is
needed. It is used for the treatment of advanced hormone-sensitive prostate
cancer in adults.
3. HOW TO TAKE THIS MEDICINE
Loading dose: 360mg (three 120mg tablets) taken on the first day of
treatment. Maintenance dose: 120mg (one tablet) once daily from day 2 onwards.
Take at the same time each day with or without food. If a dose is missed and
the next scheduled dose is more than 12 hours away, take the missed dose and
then resume the regular schedule. If less than 12 hours to the next dose, skip
the missed dose.
Relugolix should not be taken with P-glycoprotein (P-gp) inhibitors or
inducers without dose adjustment (see interactions). If a dose is missed for
more than a day, a re-loading dose of 360mg may be required — contact your
oncologist or pharmacist if you have missed multiple consecutive doses.
⚠ PATIENT TIP: Cardiovascular health is
especially important with relugolix. Unlike GnRH agonists, relugolix carries a
lower cardiovascular risk — but it still causes hot flushes, weight changes,
and other hormonal effects. Report any chest pain, breathlessness, or leg
swelling to your oncologist promptly.
4. POSSIBLE SIDE EFFECTS
|
How Common? |
Side Effects |
|
Very Common |
Hot flushes (flushing)
— the most common effect of low testosterone, fatigue, sexual dysfunction
(loss of libido, erectile dysfunction), musculoskeletal pain, anaemia,
constipation |
|
Common |
Weight gain,
hyperglycaemia (raised blood sugar), raised lipids, depression, low mood,
dizziness, hypertension, diarrhoea, rash, night sweats, decreased bone
density |
|
Serious — Tell Your
Doctor |
Bone fractures (from
osteoporosis with long-term androgen deprivation), QT interval prolongation
(heart rhythm change), cardiovascular events (though lower risk than GnRH
agonists), adrenal insufficiency (very rare — fatigue, dizziness, weight
loss, nausea if stopping abruptly after prolonged use). |
5. WHO SHOULD NOT TAKE THIS MEDICINE
Relugolix should not be used alongside strong P-glycoprotein inhibitors
(see interactions) unless carefully managed. Use with caution in patients with
a history of cardiovascular disease, QT prolongation, or osteoporosis. It is
not appropriate for female patients. Congenital long QT syndrome requires
specialist assessment before use.
⚠ BONE HEALTH: Long-term testosterone
suppression (from any form of androgen deprivation therapy) weakens bones and
increases fracture risk. Your oncologist will recommend baseline and periodic
bone density scans (DEXA) and likely prescribe calcium and vitamin D
supplements — and possibly bone-strengthening medicines (bisphosphonates or
denosumab) if bone density is low.
⚠ CARDIOVASCULAR MONITORING: Relugolix has a
lower cardiovascular risk profile than GnRH agonists, but testosterone
suppression still affects metabolic factors. Monitor blood pressure, blood
sugar, and lipids during treatment. Report chest pain, breathlessness, or leg
swelling promptly.
⚠ LOADING DOSE ON DAY 1: The treatment is
started with three tablets (360mg) on day 1, then one tablet (120mg) daily from
day 2. Ensure patients and dispensing pharmacists are aware of this loading
dose — dispensing instructions must reflect both phases.
6. MEDICINES THAT INTERACT WITH THIS TREATMENT
Strong P-glycoprotein (P-gp) inhibitors (ketoconazole, itraconazole,
clarithromycin, amiodarone, dronedarone, verapamil, cyclosporin, ritonavir)
significantly increase relugolix exposure — avoid these combinations or reduce
relugolix to 60mg daily if co-administration is unavoidable.
Strong P-gp inducers (rifampicin, carbamazepine, phenytoin, St. John's
Wort) reduce relugolix levels significantly — avoid. QT-prolonging medicines
increase cardiac risk alongside relugolix.
7. HOW TO STORE THIS MEDICINE
Store below 30°C. Keep in original packaging away from moisture and
light. Keep out of reach of children.
8. PRESCRIPTION REQUIREMENT
|
Field |
Details |
|
Status |
Prescription Only
Medicine (POM) — Specialist (urology or oncology) prescription required |
9. GUIDANCE FOR PATIENTS & CAREGIVERS
On your first day of treatment: take three 120mg tablets together (360mg
loading dose). From day 2 onwards: take one 120mg tablet every day at the same
time. Hot flushes are very common — they usually become more manageable over
time. Take calcium and vitamin D supplements as prescribed to protect your
bones.
Monitor your blood pressure, blood sugar, and weight regularly. Report
any chest pain, shortness of breath, or leg swelling to your oncologist. Tell
all your doctors and pharmacists that you are on relugolix before any new
medicine is prescribed — several common medicines interact with it.
10. PHARMACIST & PRESCRIBER NOTES
|
Field |
Details |
|
Clinical Dispensing
Notes |
GnRH receptor
antagonist — immediate testosterone suppression without initial flare (unlike
GnRH agonists). Loading dose: 360mg (three 120mg tablets) on day 1;
maintenance: 120mg daily from day 2. Ensure dispensing label and patient
counselling reflect the two-phase dosing clearly. P-glycoprotein interaction
is the primary drug interaction concern: strong P-gp inhibitors
(ketoconazole, clarithromycin, amiodarone, dronedarone, cyclosporin,
verapamil, ritonavir) increase relugolix AUC significantly — avoid or reduce
to 60mg daily with monitoring. Strong P-gp inducers (rifampicin, CBZ,
phenytoin, St. John's Wort) reduce exposure — avoid. QT monitoring if
concurrent QT-prolonging medicines. Bone health protocol: calcium + vitamin D
co-prescription; baseline and periodic DEXA scan; bisphosphonate/denosumab
referral if osteopenia/osteoporosis found. Cardiovascular monitoring: lipids,
blood glucose, BP at baseline and periodically. Hot flushes counselling.
Missed dose re-loading protocol: if >1 day missed, 360mg re-loading dose
may be required — advise patient to contact team if multiple doses missed. |
11. FREQUENTLY ASKED QUESTIONS
Q: What are the effects of having very low testosterone?
Low testosterone causes hot flushes, reduced sex drive, erectile
dysfunction, fatigue, mood changes, muscle loss, weight gain, and over time,
bone weakening (osteoporosis). These effects occur with all forms of androgen
deprivation therapy for prostate cancer — your oncology team will help manage
them and prescribe bone protection supplements.
Q: Is relugolix safer for the heart than injections?
Clinical trial data suggests relugolix has a lower cardiovascular risk
profile than injectable GnRH agonists — in particular, lower rates of major
adverse cardiovascular events. This is thought to be related to the
testosterone flare from agonists and the rapid reversibility of relugolix.
However, testosterone suppression still affects cardiovascular risk factors
(blood sugar, lipids, BP), which are monitored throughout treatment.
Q: What happens to my bones during treatment?
Testosterone is important for maintaining bone density in men. Long-term
testosterone suppression (from any androgen deprivation treatment) gradually
reduces bone density, increasing the risk of fractures. Your doctor will
prescribe calcium and vitamin D supplements, arrange a bone density scan, and
may recommend additional bone-protecting medicines if needed.
Q: What if I miss several doses?
Missing one dose is manageable — take it as soon as you remember if it is
more than 12 hours before the next dose. If you miss multiple consecutive days,
contact your oncologist or pharmacist — a re-loading dose of 360mg may be
needed to restore testosterone suppression quickly.
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