lapatinib ditosylate monohydrate: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
lapatinib ditosylate monohydrate: clinical details
Prescribing considerations
- Initiation should be by a clinician experienced in anticancer treatment, after HER2 status is confirmed using a validated method.
- Review cardiac disease, QT-risk factors, pulmonary disease, hepatic impairment, diarrhoea risk and the complete medication list.
- Moderate or severe hepatic impairment can increase exposure; experience in severe renal impairment is limited.
- Promptly assess and manage diarrhoea because severe dehydration, renal impairment and electrolyte disturbance can occur.
Contraindications and cautions
- Hypersensitivity to lapatinib or a formulation excipient.
- Check the separate contraindications and safety requirements of every co-administered anticancer treatment.
Monitoring
- Assess left-ventricular function before and during treatment.
- Check liver function before and during treatment.
- Consider ECG and potassium and magnesium assessment in patients with QT-risk factors or relevant interacting medicines.
- Monitor for diarrhoea, dehydration, pulmonary toxicity and serious cutaneous reactions.
Clinical pharmacology
Lapatinib inhibits the intracellular tyrosine kinase domains of HER2 and EGFR. Absorption is incomplete and variable and is substantially increased by food. It is highly protein-bound, extensively metabolised mainly by CYP3A4/5 and eliminated predominantly through the faecal route.
Formulation and product differences
- The selected product is a yellow, film-coated oral tablet supplied in blister packs or bottles.
- It is essentially sodium-free.
- No alternative lapatinib formulation is represented by the selected product.
lapatinib ditosylate monohydrate interactions
A full medicines review is essential, including non-prescription and herbal products.
Strong CYP3A4 inhibitors, including azole antifungals and some antivirals
They can substantially increase lapatinib exposure and toxicity, so combined use should be avoided.
CYP3A4 inducers, including rifampicin, carbamazepine, phenytoin and St John's wort
They can lower lapatinib exposure and potentially reduce its effect, so combined use should be avoided.
Proton-pump inhibitors and other medicines that raise stomach pH
They may reduce lapatinib solubility and absorption and should generally be avoided.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.