Herlapsa Tablet contains Lapatinib 250 mg, a tyrosine kinase inhibitor used primarily in the treatment of advanced or metastatic breast cancer that overexpresses the human epidermal growth factor receptor 2 (HER2). Lapatinib functions by selectively inhibiting the intracellular tyrosine kinase domains of both HER2 and epidermal growth factor receptor (EGFR), thereby blocking downstream signaling pathways involved in tumor cell proliferation and survival. This targeted mechanism of action makes Herlapsa effective in patients with HER2-positive breast cancer, particularly those who have progressed following prior therapies such as trastuzumab and chemotherapy. The tablet is indicated for use in combination with capecitabine or as monotherapy in cases where other treatments are unsuitable. Common adverse effects include diarrhea, rash, nausea, fatigue, and hepatotoxicity, necessitating regular monitoring of liver function tests during therapy. Dose adjustments may be required based on tolerability and hepatic function. Herlapsa should be administered under the supervision of an oncologist experienced in cancer chemotherapy. It is contraindicated in patients with known hypersensitivity to Lapatinib or any tablet excipients. Caution is advised during pregnancy and lactation due to potential teratogenic effects. Proper patient counseling on adherence and side effect management is essential for optimal therapeutic outcomes.