Lapatinib

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Generic Name of Lapatinib - Learn More

Lapatinib

Lapatinib Precaution - What You Need to Know

Before starting Lapatinib, it is essential for patients to consult with their healthcare provider due to the following precautions:

- Cardiotoxicity: Lapatinib has been associated with cardiac events, including heart failure and decreased left ventricular ejection fraction. Patients with pre-existing heart conditions, especially those with a history of heart disease, should be closely monitored for signs of heart-related symptoms, such as shortness of breath, swelling in the legs, or fatigue.
- Liver Function: Lapatinib can cause hepatic toxicity, including hepatitis or elevated liver enzymes. Liver function tests should be conducted regularly, particularly in patients with pre-existing liver conditions such as hepatitis B or cirrhosis.
- Diarrhea: One of the most common side effects of Lapatinib is diarrhea. It can be severe, and patients should be instructed to manage this symptom immediately, especially in cases of dehydration. Oral rehydration and anti-diarrheal medications may be recommended.
- Pregnancy and Breastfeeding: Lapatinib is classified as a Category D drug, which means it can cause harm to the fetus. It should not be used during pregnancy, and women of childbearing potential should use effective contraception while on treatment. The drug is also excreted in breast milk, so breastfeeding is not recommended during therapy.
- Drug Interactions: Lapatinib can interact with other drugs, potentially affecting its effectiveness or leading to increased toxicity. For example, antacids, H2 blockers, or proton pump inhibitors can reduce its absorption. It is important to inform healthcare providers about all medications being taken.

Lapatinib Indication - Uses and Benefits

Lapatinib is an oral targeted therapy used in the treatment of certain types of breast cancer, specifically:

- HER2-positive Breast Cancer: Lapatinib is primarily used to treat HER2-positive metastatic or advanced breast cancer in combination with other medications such as capecitabine or letrozole.
- HER2 (Human Epidermal Growth Factor Receptor 2) is a protein that promotes the growth of cancer cells. In HER2-positive cancers, this receptor is overexpressed, making the cancer cells more aggressive. Lapatinib works by inhibiting both HER2 and EGFR (Epidermal Growth Factor Receptor), which are involved in cancer cell proliferation.
- Treatment of Advanced or Metastatic Breast Cancer: Lapatinib is specifically indicated in patients whose disease has progressed after previous chemotherapy regimens or trastuzumab treatment, and those with resistant cancer that requires another line of therapy.
- Combination Therapy: It is often used in combination with capecitabine for patients with HER2-positive metastatic breast cancer, especially when trastuzumab has not been effective.

Lapatinib Contraindications - Important Warnings

Lapatinib should not be used in the following situations:

- Hypersensitivity: Lapatinib is contraindicated in patients who have a known hypersensitivity or allergy to Lapatinib or any of its components. Severe allergic reactions such as rash, itching, and difficulty breathing may occur.
- Severe Liver Disease: The drug should not be used in patients with severe hepatic impairment due to the increased risk of liver toxicity. Liver function should be assessed prior to starting treatment.
- Pregnancy: Lapatinib is contraindicated in pregnancy due to its potential to cause fetal harm. It is classified as a Category D drug, and women of childbearing potential should use effective contraception.
- Severe Heart Disease: Lapatinib should be avoided in patients with severe cardiac conditions, particularly those with heart failure or significant arrhythmias, due to its potential effects on cardiac function.

Lapatinib Side Effects - What to Expect

Lapatinib can cause several side effects, ranging from mild to severe:

- Common Side Effects:
- Diarrhea: This is the most frequent side effect and can sometimes be severe. It may lead to dehydration, requiring the use of anti-diarrheal medications.
- Skin Rash: A rash, particularly on the face or upper torso, is common, and it may sometimes lead to itching or skin irritation.
- Nausea and vomiting.
- Fatigue or malaise.
- Loss of appetite and weight loss.
- Mouth sores or stomatitis.

- Severe Side Effects:
- Cardiotoxicity: The risk of heart failure and other cardiac issues, including arrhythmias, can be significant, particularly in patients with pre-existing heart conditions.
- Liver Toxicity: Elevated liver enzymes (ALT, AST) and hepatitis have been reported. Symptoms of liver dysfunction include yellowing of the skin or eyes (jaundice), dark urine, or persistent abdominal pain.
- Severe Diarrhea: In rare cases, Lapatinib-induced diarrhea can be severe enough to lead to dehydration, requiring hospitalization.
- Interstitial Lung Disease (ILD): A rare but severe lung condition characterized by cough, shortness of breath, and fever.

Lapatinib Pregnancy Category ID - Safety Information

4

Lapatinib Mode of Action - How It Works

Lapatinib is a small molecule tyrosine kinase inhibitor that targets HER2 (Human Epidermal Growth Factor Receptor 2) and EGFR (Epidermal Growth Factor Receptor). It works by blocking the signaling pathways that promote the growth of cancer cells, specifically in HER2-positive breast cancer cells.

- HER2 Inhibition: HER2 is a receptor protein overexpressed in some cancers, leading to uncontrolled cell division. Lapatinib binds to and inhibits this receptor, preventing the cancer cells from proliferating.
- EGFR Inhibition: In addition to HER2, Lapatinib also targets EGFR, a receptor involved in cellular growth and survival. By inhibiting both HER2 and EGFR, Lapatinib blocks key growth signals in cancer cells.
- Cancer Cell Growth Inhibition: This inhibition leads to the reduced growth and death of HER2-positive cancer cells, making it effective in treating HER2-positive breast cancer.

Lapatinib Drug Interactions - What to Avoid

Lapatinib can interact with several drugs, potentially altering its effectiveness or leading to serious side effects:

- Antacids and Proton Pump Inhibitors (PPIs): These drugs can reduce the absorption of Lapatinib by altering stomach pH. Therefore, Lapatinib should be taken at least 1 hour before or 2 hours after antacids, H2 blockers, or PPIs.
- CYP3A4 Inhibitors: CYP3A4 is a liver enzyme involved in the metabolism of Lapatinib. Drugs that inhibit CYP3A4, such as ketoconazole, ritonavir, and some antibiotics, may increase the levels of Lapatinib, leading to an increased risk of side effects.
- CYP3A4 Inducers: Conversely, CYP3A4 inducers, such as rifampin, can lower the concentration of Lapatinib, reducing its effectiveness.
- Digoxin: Lapatinib can interact with digoxin, a drug used for heart conditions, by increasing its levels and potentially leading to digoxin toxicity.
- St. John’s Wort: This herbal supplement is a known CYP3A4 inducer, and its use can decrease the effectiveness of Lapatinib.
- Warfarin: Caution should be used when administering Lapatinib with warfarin, as Lapatinib can affect blood clotting and alter warfarin’s effectiveness.

Lapatinib Adult Dose - Recommended Dosage

The typical adult dosing for Lapatinib in the treatment of HER2-positive breast cancer is:

- Initial Dose: 1250 mg orally once daily.
- In combination with Capecitabine: Often given in combination with capecitabine (1250 mg/m2 twice daily).
- Dosage Adjustments: Dose modifications may be necessary based on side effects such as diarrhea, liver toxicity, or cardiotoxicity.

Lapatinib Child Dose - Dosage for Children

Lapatinib is generally not recommended for use in pediatric patients due to a lack of established safety and efficacy in children. The drug is used predominantly in adults with HER2-positive breast cancer.

As always, patients should consult their healthcare provider to determine appropriate dosing and to address any concerns regarding potential side effects or interactions.

Lapatinib Renal Dose - Dosage for Kidney Conditions

No specific renal dosing adjustments are required for Lapatinib in patients with mild to moderate renal impairment. However, liver function should be monitored, as Lapatinib is primarily metabolized by the liver.