LabCorp-owned Covance mooted the idea of selling the Alnwick site last September.
Covance bought the site from Sanofi in 2010 in a deal that also saw it contracted to provide discovery, toxicology and chemistry services for five years.
The research services deal with Sanofi - which also saw Covance buy a facility in Porcheville, France - came to an end last year.
A Covance spokeswoman told us the end of the Sanofi deal coupled with the challenging preclinical market prompted the sale.
She added that: "The site and its operations was transferred to ARC Trinova. ARC Trinova will continue to provide certain capabilities to Covance that are linked to the work performed at other Covance sites in United Kingdom. Some of the capabilities that ARC will discontinue at the Alnwick site will continue to be provided through Covance."
The Alnwick site provided CMC & Synthetic Chemistry, Bioanalysis, drug metabolism & pharmacokinetics (DMPK) and safety assessment services for pharmaceuticals development.
Covance employed 130 people at the laboratory.
The preclinical contract research organisation's (CRO) spokeswoman told us: "The majority of the staff transferred to ARC Trinova.
"As part of the agreement ARC Trinova agreed to retain a minimum of 50 employees and will continue to provide certain capabilities to Covance that are linked to the to work performed at other Covance sites in United Kingdom."
New owner ARC Trinova said it "will add capability in active pharmaceutical ingredient (API) process development and scale up to the multi-kilogram level."