The Clinical Pharmacokinetics of Lu AA21004 and its Major Metabolite in Healthy Young Volunteers

Lu AA21004 is a novel multimodal antidepressant that is currently in phase 3 development. The objective of this report was to detail the clinical pharmacokinetics of Lu AA21004 and its major but inactive metabolite Lu AA34443 (3-methyl-4-(2-piperazine-1-yl-phenylsulfanyl)-benzoic acid) in healthy men and women aged between 18 and 53 years. Data from two single-dose and one multiple-dose study were combined; the total number of volunteers was 97 (64 men, 33 women). Blood and urine samples were collected after p.o. and i.v. administrations to determine the content of Lu AA21004 and Lu AA34443 performed with a validated method. Standard pharmacokinetic parameters were estimated with non-compartmental analysis. The absolute bioavailability was 75%. After oral administration, Lu AA21004 showed an extended absorption phase, a medium clearance and a large volume of distribution resulting in late t(max) values and a mean elimination half-life of 57 hr. The exposure of Lu AA21004 showed a linear relationship with dose in the dose ranges studied (up to 75-mg single dosing and 60-mg multiple dosing). After weight correction, no differences in exposure for Lu AA21004 and Lu AA34443 were observed between men and women. The renal clearance of Lu AA21004 was negligible. The major metabolite Lu AA34443 had a half-life similar to that of Lu AA21004 but a lower accumulation ratio at steady-state, indicating formation-rate-limited elimination. In conclusion, Lu AA21004 showed an extended absorption phase, a medium clearance and a large volume of distribution.