Although thiotepa is chemically less reactive than the ni-trogen mustards, it is thought to act by similar mecha-nisms. Its oral absorption is erratic. After intravenous in-jection, the plasma half-life is less than 2 hours. Urinary excretion accounts for 60 to 80% of eliminated drug.
Thiotepa has antitumor activity against ovarian and breast cancers and lymphomas. However, it has been largely supplanted by cyclophosphamide and other ni-trogen mustards for treatment of these diseases. It is used by direct instillation into the bladder for multifo-cal local bladder carcinoma.
Nausea and myelosuppression are the major toxici-ties of thiotepa. It is not a local vesicant and has been safely injected intramuscularly and even intrathecally.