Lapatinib, with brand names Tykerb® and Tyverb®, is a drug frequently prescribed with another drug called capecitabine for patients diagnosed with advanced breast cancer. It belongs to a class of medications known as tyrosine kinase inhibitors, a specific group of cancer treatment drugs. Tyrosine kinase is a protein usually found inside cancer cells that helps promote their growth. Inhibiting the activation of this protein often prevents the activation of cancer cells, thus, stopping them from growing and spreading.
Breast cancer cells usually have two receptors, the human epidermal growth factor receptor 2 (HER2) and the epidermal growth factor receptor (EGFR). These receptors are known to be capable of activating tyosine kinase. Lapatinib generally acts by targeting these receptors to stop the activation of tyrosine kinase. Most physicians usually first check the level of HER2 and EGFR in breast cancer cells before they prescribe lapatinib.
Patients who do not respond well to other breast cancer medications are usually given lapatinib. This 250-milligram (mg) yellow tablet is usually taken by mouth one hour before or after eating a meal. Doctors often provide specific instructions on what dosage to take, how often to take the medicine, and now long to continue taking the medicine. They may also advise patients to avoid drinking grapefruit juice, as this can have interactions with the drug. It is often important for patients to follow their doctor's prescription and not to stop taking the medications on their own.
The use of lapatinib is often associated with some side effects. One severe side effect of taking this drug is liver damage. Indications of liver damage include itching, passing dark urine or pale-colored stools, unusual bleeding, and pain in the upper section of the right side of the abdomen. Heart functions may also be impacted. Patients are thus monitored regularly to check their heart and liver functions while taking this drug.
Other possible side effects of lapatinib are diarrhea, acid reflux, loss of appetite, mouth sores, and dry skin. Patients may also experience joint pains, headaches, and sleeping problems. When they observe difficulty breathing, coughing out blood, swelling of some body parts, and fast or irregular heartbeats, patients are usually advised to consult with their physician immediately. Taking more lapatinib tablets than recommended can often lead to overdose and may need immediate medical attention. Overdose symptoms include vomiting and nausea.