Dr Alexander graduated as a veterinarian from Massey University in 1968. After a period in practice, he commenced post graduate studies at the Ontario Veterinary College, Guelph, Canada.  He then spent 5 years developing new techniques for commercialising embryo transplantation in cattle.  This was followed by four years in the NZ veterinary school as the Poultry Pathologist and at the same time acted as the consultant to the major manufacturer of pig and poultry feed in NZ.

In 1986, Alan was appointed the first director of the newly established CRO, now Estendart Research Ltd, wholly owned by Massey University.  In 1997, Alan was responsible for establishing this CRO as the first research organisation in NZ to be GLP accredited.  In 2000, Dr Alexander was appointed Head of the Veterinary Clinical Trials Unit at Charles River Ltd, Edinburgh.  He spent five years in this role before moving to Novartis Animal Health, Sydney as Head of R&D.  In 2008, he returned to NZ to become General Manager of Estendart Ltd and extended the company’s activities into medical pharmaceuticals and devices. When Estendart Ltd was acquired Invetus Pty Ltd in 2018, Alan became the Executive Director of Estendart Research Centre of Invetus NZ, Palmerston North before retiring from this role in 2020.  Since then, he has focussed on repositioning Niclosamide as a therapeutic to treat COVID-19.

In 2024, Alan and his company Estendart Holdings, became the sole shareholder of Estendart Research Ltd (ERL) after Invetus Pty Ltd withdrew from its presence in NZ. ERL continues to operate as a new, modernised and now, a New Zealand-owned and operated, Contract Research Organisation.