Lomustine (Specialist drug)

How it works

It alkylates and carbamoylates DNA, causing cross-linking that disrupts DNA replication and transcription, and is lipophilic enough to cross the blood-brain barrier.

Prescribing in practice

• Causes delayed, cumulative and potentially severe bone-marrow suppression (notably delayed thrombocytopenia and leukopenia), so courses are given at long intervals and a full blood count must be checked before each course.
• It is given as a single oral dose repeated only after an extended interval, and fatal overdose has occurred when patients took it more frequently than prescribed — dispensing and counselling must guard against this.
• Cumulative dosing is associated with pulmonary fibrosis and nephrotoxicity, so lifetime exposure is monitored and lung and renal function reviewed.

Monitoring

Monitor full blood count before each course and for a prolonged period afterwards, with periodic liver, renal and pulmonary function assessment over cumulative therapy.

Counselling the patient

• Take only the dose your specialist team prescribes and never repeat it early — taking it more often than instructed can be fatal.
• Report fever, unusual bruising or bleeding, breathlessness or persistent cough promptly.
• Effective contraception is needed during and after treatment as the drug can harm a pregnancy.

Evidence & guidelines

Use is supported by established oncology practice and the SPC; treatment should follow specialist protocols.