Tolerance of nicotinamide and carbogen with radiation therapy for glioblastoma.

Nineteen patients with glioblastoma were treated with nicotinamide and carbogen and radiotherapy. Eight patients did not complete the protocol because of hepatic toxicity from phenytoin/nicotinamide drug interactions, persistent nausea or vomiting with nicotinamide, intolerance of the carbogen breathing apparatus, or other reason. In addition, early radiation neurotoxicity appeared increased.