The patient is paralyzed from childhood due to injury to the spinal cord. He is 64 years of age. After 3 days of keflex 500mg every 6hours, he developed auditory hallucinations while rousted from a sleep state, He had a flatening of his affect. The drug was reduced to q12hrs. Currently he is becoming increasingly hostile and accusatory after the slightest infraction... lacks insight and seems to challange any confrontation in a taunting manner. Have seen this before with drugs that cross the blood brain barrier. Please advise...