osimertinib mesylate: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
osimertinib mesylate: clinical details
Prescribing considerations
- Initiation should be supervised by a clinician experienced in anti-cancer treatment.
- Confirm the relevant EGFR mutation using a validated assay; follow a negative plasma result with tissue testing where possible in advanced disease.
- Review pulmonary history, cardiac disease, QT-risk factors, interacting medicines, eye disease, hepatitis B status, reproductive plans and organ impairment.
- Older people and patients with low body weight may require closer toxicity surveillance.
- Safety and efficacy are not established in children, end-stage renal disease or severe hepatic impairment.
Contraindications and cautions
- Hypersensitivity to osimertinib or an excipient.
- Concurrent St John’s wort.
- Avoid where possible in congenital long-QT syndrome; clinically active interstitial lung disease requires specialist risk assessment.
Monitoring
- Assess promptly for unexplained cough, fever or breathlessness and investigate suspected interstitial lung disease.
- Monitor full blood count and investigate persistent fever, infection, pallor, bruising or bleeding for possible aplastic anaemia.
- Consider ECG and electrolytes in patients with cardiac failure, electrolyte disturbance or concurrent QT-prolonging treatment.
- Consider baseline and subsequent left-ventricular function assessment in patients with cardiac risk factors or relevant symptoms.
- Monitor patients with positive hepatitis B serology for clinical and laboratory evidence of reactivation.
- Arrange prompt ophthalmology assessment for symptoms suggestive of keratitis.
Clinical pharmacology
An irreversible inhibitor of sensitising-mutant EGFR and the T790M resistance mutation. It is metabolised mainly through CYP3A pathways, has active metabolites, inhibits BCRP and P-glycoprotein, and distributes extensively into tissues.
Formulation and product differences
- The selected product is a film-coated oral tablet.
- The tablet must not be crushed, split or chewed but can be dispersed in still water when swallowing is difficult.
- A product-specific dispersion procedure supports administration through a nasogastric tube.
osimertinib mesylate preparations and strengths
Tablet
Route: Oral
Strengths: 40 mg, 80 mg
osimertinib mesylate interactions
Check prescription, non-prescription and herbal products before treatment and whenever medicines change.
St John’s wort
Must not be used because it can substantially reduce osimertinib exposure.
Strong CYP3A inducers, including rifampicin, carbamazepine and phenytoin
May reduce osimertinib exposure and should generally be avoided.
Moderate CYP3A inducers, including bosentan, efavirenz, etravirine and modafinil
May reduce osimertinib exposure and require careful specialist review.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.