WHAT IS THIS MEDICINE AND WHAT IS IT USED FOR?
Palbonix 125mg is the standard starting dose of palbociclib for adults
with hormone receptor-positive (HR+), HER2-negative advanced or metastatic
breast cancer.
It is used in adults for hormone receptor-positive (HR+), HER2-negative
advanced or metastatic breast cancer — the most common type of breast cancer.
It is used in combination with a hormonal medicine: either an aromatase
inhibitor (such as letrozole or anastrozole) as a first treatment for
postmenopausal women and men, or fulvestrant (following previous hormonal
therapy).
The 125mg capsule is used first, and if significant side effects occur —
particularly low white blood cell counts (neutropenia) — the dose is stepped
down to 100mg (entry 136), then to 75mg if needed.
3. HOW TO TAKE THIS MEDICINE
One 125mg capsule once daily for 21 days, followed by 7 days off (one
28-day cycle). Take with food at the same time each day. Swallow whole — do not
open, crush, or chew. Always take alongside your co-prescribed hormonal
medicine (aromatase inhibitor or fulvestrant). If you vomit after taking a
dose, do not take a replacement dose that day.
At 125mg, neutropenia (low white blood cell count) is more common than at
lower doses. Blood count monitoring before treatment, before each cycle, and at
day 15 of the first two cycles is essential. This is the standard starting dose
— your oncologist will step the dose down if needed based on how your body
responds.
⚠ PATIENT TIP: If your blood counts come back
low and your next cycle is delayed, try not to be alarmed — this is a common
and expected part of managing palbociclib safely. Your team will restart your
cycle as soon as it is safe to do so. Use the break time to rest and recover.
4. POSSIBLE SIDE EFFECTS
|
How Common? |
Side Effects |
|
Same as 100mg |
Neutropenia, anaemia,
thrombocytopenia, fatigue, nausea, mouth sores, hair thinning, diarrhoea,
decreased appetite |
|
Higher Frequency at
125mg |
Neutropenia rates are
higher at 125mg — this is the most common reason for dose reduction. Blood
count monitoring is even more important at this starting dose. |
|
Serious — Same as
100mg |
Febrile neutropenia
(fever above 38°C with low blood counts — go to hospital immediately).
Unusual bleeding. Signs of serious infection. |
5. WHO SHOULD NOT TAKE THIS MEDICINE
Avoid strong CYP3A4 inhibitors and inducers, grapefruit juice.
Contraindicated in pregnancy.
⚠ NEUTROPENIA IS MORE COMMON AT 125MG: White
blood cell counts tend to fall more at the standard starting dose. Blood count
monitoring at day 15 of cycles 1 and 2 is particularly important to detect
significant neutropenia early.
⚠ FEVER EMERGENCY PLAN: Know what to do before
you start treatment — if your temperature reaches 38°C or above at any time
during a cycle, go to hospital immediately. Do not take paracetamol first to
bring the fever down without seeking assessment.
⚠ ALL WARNINGS FROM ENTRY 136 APPLY: Including
CYP3A4 interactions, grapefruit avoidance, contraception requirements, and
cycle schedule adherence.
6. MEDICINES THAT INTERACT WITH THIS TREATMENT
Avoid strong CYP3A4 inhibitors (ketoconazole, clarithromycin, grapefruit
juice) and inducers (rifampicin, St. John's Wort, carbamazepine).
7. HOW TO STORE THIS MEDICINE
Store below 25°C. Keep in original packaging. Protect from light and
moisture. Keep out of reach of children.
8. PRESCRIPTION REQUIREMENT
|
Field |
Details |
|
Status |
Prescription Only
Medicine (POM) — Specialist (oncology) prescription required |
9. GUIDANCE FOR PATIENTS & CAREGIVERS
Take one 125mg capsule once daily with food for 21 days, then take 7 days
off, then restart. At this dose, your blood counts will be checked carefully —
especially in your first two cycles. If your white blood count falls
significantly, your next cycle may be delayed or your dose reduced to 100mg.
This is a normal part of treatment management, not a sign of treatment failure.
Go straight to hospital if your temperature reaches 38°C. Avoid grapefruit. Use
effective contraception.
10. PHARMACIST & PRESCRIBER NOTES
|
Field |
Details |
|
Clinical Dispensing
Notes |
125mg is the standard
starting dose of palbociclib. Neutropenia incidence is higher at this dose —
reinforce FBC monitoring schedule (pre-treatment, pre-cycle, day 15 cycles 1
and 2). Febrile neutropenia emergency counselling mandatory. If patient has
already received 125mg and is being prescribed 100mg — confirm dose reduction
is intentional and update monitoring records. All interaction screening,
contraception, and clinical monitoring protocols identical to 100mg entry
(136). Do not open or crush capsules. Confirm hormonal partner medicine (AI
or fulvestrant) is co-dispensed. |
11. FREQUENTLY ASKED QUESTIONS
Q: What happens if my white blood count drops too low?
Your next cycle will be delayed to give your bone marrow time to recover.
If counts consistently fall too low at 125mg, your dose will be reduced to
100mg. This is expected and does not mean palbociclib is not working against
your cancer.
Q: Can I take the capsule at night to avoid nausea during the day?
Yes — some patients find taking palbociclib in the evening with their
evening meal helps manage nausea. As long as you take it with food and at the
same time each day, evening dosing is acceptable. Discuss this preference with
your oncologist.
Q: What if I accidentally take two doses in one day?
Contact your oncology team or pharmacist immediately for advice. Do not
take an extra dose to make up for a missed one on a previous day.
Q: Do I need to tell my dentist I am on this medicine?
Yes — inform your dentist you are on palbociclib and undergoing cancer
treatment, particularly if you need any dental procedures. Low platelet counts
(thrombocytopenia) can increase bleeding risk during dental work.