Clinical pharmacology of SQ 10,996, a potential antidepressive agent

Single oral doses of SQ 10,996 ranging from 500 to 1000 mg (0.34 to 15.3 mg/kg), given once daily for 3 consecutive days to groups of healthy volunteers, were well tolerated. One of three subjects given 1250 mg (17.1 mg/kg) and two of three subjects given 1500 mg (15.6 and 21.4 mg/kg) became drowsy on the second and third days; this symptom disappeared within 24 hrs after cessation of dosage. A short-term, multiple-dose tolerance study was carried out with a formulation of SQ 10,996, the bioavailability of which was comparable to that of the formulation used earlier in the ascending-dose tolerance study. When 200-mg doses were administered every 12, 8, or 6 hrs over a 6-day period, mean steady-state serum concentrations of approximately 4, 7, and 8 mug/ml were attained within 48 hrs; unexpectedly, no subject showed any sign of drowsiness. The half-life for SQ 10,996 in serum, estimated from concentrations in serum after the last dose, was approximately 13 hrs, significantly shorter than the half-life found previously after the administration of single 10-mg doses. These clinical pharmacology studies in healthy volunteers have shown SQ 10,996 to be biologically available and well tolerated. Future studies will test its antidepressive potential in patients.