Palker125 mg

Palker is a targeted oncology medicine (a CDK4/6 inhibitor) used in adults for the treatment of hormone receptor (HR)-positive, HER2-negative advanced or metastatic breast cancer. It is not used alone; it is always combined with another hormonal (endocrine) therapy.

• Established, FDA-approved use (first-line/initial therapy): Palker in combination with an aromatase inhibitor (e.g. letrozole) as initial endocrine-based therapy in postmenopausal women, or in men, with HR-positive, HER2-negative advanced or metastatic breast cancer.
• Established, FDA-approved use (after disease progression): Palker in combination with fulvestrant in patients with disease progression after prior endocrine therapy.
• Newer approved combination (biomarker-selected): Palker together with inavolisib and fulvestrant for endocrine-resistant, PIK3CA-mutated, HR-positive, HER2-negative disease that has recurred during or after adjuvant endocrine therapy.
• In pre/perimenopausal women, Palker-based combinations are given together with an LHRH agonist (ovarian suppression) as per standard oncology practice.

Palker is a specialist oncology medicine; it must only be prescribed and monitored by, or in consultation with, a qualified oncologist. It is not indicated for early-stage/curative-intent breast cancer or for cancers other than the HR-positive, HER2-negative subtype described above.

Each film-coated tablet contains Palbociclib as the active ingredient, commonly available in strengths of 75 mg, 100 mg, and 125 mg (capsule formulations of the same strengths also exist in some markets). Tablets/capsules contain standard pharmaceutical excipients such as microcrystalline cellulose, lactose, and film-coating agents; formulation details can vary slightly by manufacturer.

Palker is an orally administered, small-molecule cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor used in the treatment of hormone receptor-positive, HER2-negative advanced breast cancer. It was among the first drugs in its class to receive regulatory approval and is used worldwide in combination with endocrine therapy to slow tumor growth by blocking a key cell-division pathway that hormone-driven breast cancer cells rely on.

Palker is dispensed only against a specialist prescription and is administered as part of a supervised oncology treatment plan that includes regular blood monitoring.

Palker belongs to the CDK4/6 inhibitor class of targeted antineoplastic (anticancer) agents, used as part of endocrine-based combination therapy for breast cancer.

Mechanism of Action

Palbociclib reversibly inhibits cyclin-dependent kinases 4 and 6 (CDK4/6), enzymes that, together with cyclin D1, normally phosphorylate the retinoblastoma (Rb) protein. By blocking this phosphorylation, Palbociclib keeps Rb in its active, hypophosphorylated form, which halts progression of hormone receptor-positive breast cancer cells from the G1 to the S phase of the cell cycle. This produces cell-cycle arrest and, in combination with endocrine therapy that blocks estrogen-driven signaling, a synergistic anti-tumor effect.

Pharmacokinetics

• Absorption: Peak plasma concentration is reached approximately 6-12 hours after an oral dose; can be taken with or without food.
• Distribution: Moderately protein bound (~85%).
• Metabolism: Primarily hepatic, mainly via CYP3A and sulfotransferase (SULT2A1) enzymes.
• Elimination half-life: Approximately 29 hours, supporting once-daily dosing.
• Excretion: Predominantly in feces, with a smaller fraction in urine.

• Take Palker at approximately the same time each day, with or without food.
• Swallow tablets/capsules whole; do not chew, crush, dissolve, or split them, and do not take a tablet/capsule that is broken, cracked, or otherwise not intact.
• Avoid grapefruit or grapefruit juice while taking Palker (see Interactions).
• Follow the 21-days-on/7-days-off cycle exactly as prescribed; do not adjust the schedule or dose on your own.
• If a dose is missed or vomited, do not take an extra dose that day — simply resume with the next scheduled dose.

Strong CYP3A Inhibitors

Drugs such as ketoconazole, itraconazole, clarithromycin, ritonavir, and grapefruit/grapefruit juice significantly increase blood levels of Palker, raising the risk of toxicity (especially neutropenia). Concurrent use should be avoided; if unavoidable, the treating physician will reduce the Palker dose and monitor closely.

Strong CYP3A Inducers

Drugs such as rifampin, carbamazepine, phenytoin, and St. John's Wort can substantially lower Palker blood levels and reduce its effectiveness. Concurrent use should be avoided.

Sensitive CYP3A Substrates

Palker can increase blood levels of drugs that are sensitive CYP3A substrates with a narrow therapeutic index (e.g. certain statins such as simvastatin, some ergot derivatives, certain calcium channel blockers). Dose adjustment of the co-administered drug may be needed; inform your physician about all other medicines you take.

QT-Prolonging Drugs

Caution is advised when combining Palker with other medicines known to prolong the QT interval, due to an additive risk of cardiac rhythm disturbance.

Very Common

• Neutropenia (low neutrophil count) — the most frequent significant laboratory abnormality; see Precautions for monitoring requirements
• Leukopenia, anemia, and thrombocytopenia (reduced white cells, red cells, and platelets)
• Fatigue and weakness
• Nausea, stomatitis (mouth sores), diarrhea, decreased appetite
• Alopecia (hair thinning/loss)
• Elevated liver enzymes (ALT/AST)
• Increased susceptibility to infections

Less Common but Serious

• Febrile neutropenia and, rarely, neutropenic sepsis
• Interstitial lung disease/pneumonitis — can be severe or, rarely, fatal; requires prompt evaluation of new or worsening respiratory symptoms (cough, shortness of breath, fever)
• Hepatotoxicity (significant liver enzyme elevation)
• QT interval prolongation
• Rash

Patients should report any fever, signs of infection, unusual bleeding/bruising, new breathing difficulty, or persistent illness to their oncology team promptly while taking Palker.

Pregnancy

Animal studies show that Palker can cause embryo-fetal harm. Palker should not be used during pregnancy unless there is no safer alternative and the potential benefit is judged by the treating physician to justify the potential risk to the fetus; a pregnancy test is generally recommended before starting treatment. Patients of reproductive potential should use effective, non-hormonal contraception during treatment and for a period after the last dose as advised by their oncologist; male patients with partners of reproductive potential should also use effective contraception. Consult a physician immediately if pregnancy occurs or is suspected during treatment.

Lactation

It is not known whether Palker passes into human breast milk. Because of the potential for serious adverse effects in a breastfeeding infant, breastfeeding is not recommended during treatment with Palker and for a period after the last dose, as advised by the treating physician.

• Neutropenia/myelosuppression: The most common serious laboratory abnormality with Palker. Complete blood counts must be monitored before starting treatment, at the start of each cycle, on day 15 of the first two cycles, and as clinically indicated thereafter. Dose interruption, reduction, or delay is used to manage significant neutropenia (see Dosage and Administration).
• Interstitial lung disease (ILD)/pneumonitis: Can be severe and, rarely, fatal. Monitor for pulmonary symptoms (cough, dyspnea, hypoxia, fever) and interrupt or discontinue Palker as directed by the treating physician if ILD/pneumonitis is diagnosed.
• Hepatotoxicity: Liver function tests should be monitored periodically; dose modification may be required for significant enzyme elevation.
• QT interval prolongation: Use with caution in patients with a history of QT prolongation, relevant cardiac disease, or electrolyte abnormalities, and with other QT-prolonging drugs; ECG and electrolyte monitoring may be recommended in at-risk patients.
• Embryo-fetal toxicity: Effective contraception is required during treatment and for a period afterward for patients of reproductive potential and for male patients with partners of reproductive potential (see Pregnancy and Lactation).
• Grapefruit interaction: Avoid grapefruit and grapefruit juice, which can raise Palker blood levels (see Interactions).
• Specialist supervision required: Palker must be prescribed and monitored only by, or under the direct guidance of, a qualified oncologist, with access to regular laboratory monitoring. It is not a general-practice medication and should never be self-adjusted or shared with others.

There is limited clinical experience with Palker overdose. Based on its known effects, overdose may be expected to worsen bone marrow suppression (severe neutropenia, anemia, thrombocytopenia) and gastrointestinal symptoms such as nausea and vomiting. There is no specific antidote for Palker overdose.

If an overdose is suspected, seek immediate medical attention or contact a poison control center/emergency services right away. Treatment is supportive and symptomatic, including close monitoring of blood counts, under hospital care.

Store at room temperature (below 30°C), away from light and moisture. Keep out of reach of children.

Renal Impairment

No dose adjustment is generally required for mild to moderate renal impairment. Data in patients with severe renal impairment are limited; use Palker with caution and increased monitoring in this group.

Hepatic Impairment

No dose adjustment is needed for mild to moderate hepatic impairment (Child-Pugh A/B). For severe hepatic impairment (Child-Pugh C), a reduced starting dose of 75 mg once daily is recommended (see Dosage and Administration).

Elderly Patients

No overall differences in effectiveness have been observed between elderly and younger adult patients, but as with all patients, regular monitoring for adverse effects such as neutropenia and infection is important.

Pediatric Patients

Safety and efficacy of Palker have not been established in pediatric patients; it is not indicated for use in children.

Treatment with Palker is generally continued in repeating 28-day cycles (21 days on, 7 days off) for as long as the patient continues to benefit clinically and does not experience unacceptable toxicity, as determined by the treating oncologist through periodic clinical and laboratory assessment. Treatment duration is individualized and should never be extended, shortened, or stopped without the oncologist's guidance.

Palbociclib is classified as a CDK4/6 inhibitor, a subclass of targeted antineoplastic (anticancer) agents used in combination with endocrine therapy for hormone receptor-positive breast cancer.

Palbociclib selectively and reversibly inhibits cyclin-dependent kinases 4 and 6 (CDK4/6). In hormone receptor-positive breast cancer cells, CDK4/6 normally partner with cyclin D1 to phosphorylate the retinoblastoma (Rb) protein, allowing cells to pass from the G1 phase into the S phase of the cell cycle and proliferate. By blocking CDK4/6 activity, Palbociclib prevents Rb phosphorylation, arresting susceptible tumor cells in the G1 phase. When combined with endocrine therapy that reduces estrogen receptor signaling, this produces a synergistic reduction in tumor cell proliferation.

The safety and efficacy of Palker have not been established in pediatric patients. Palker is not indicated for use in children or adolescents, and it should only be used in adult patients meeting the approved indication under specialist oncology supervision.