Abstract
We studied the safety of butorphanol in different 5 doses (0.5, 1.0, 2.0, 3.0, 4.0mg) administered intramuscularly in healthy Japanese male volunteers.
No remarkable abnormalities were observed in subjective and objective symptoms, vital signs, ECG or laboratory tests. Sedation was observed characteristically in almost every cases. Constipation, specific adverse effect of opiates, was not reported. Respiratory depression was slight and was not dose-dependent. Psychotomimetic reaction such as nightmare or hallucination was not observed. We confirmed butorphanol was the drug of wide safety margins and little adverse effects.
Therefore, we concluded that we can proceed to phase two study with this drug.
