Pfizer Nigeria has been facing allegations in Nigeria that it caused the death of 11 children in 1996 when it "unlawfully" conducted a clinical trial of its meningitis drug Trovan (trovafloxacin) in an area of the country called Kano.
Last week saw the arrest and release on bail of Segun Dogunro, a doctor who worked as the medical director of Pfizer Nigeria at the time the trials in question took place and who is being targeted through the courts.
He is one of a number of former senior level staff members who had a warrant for their arrest issued against them in December by the Kano state high court, for allegedly ignoring a summons to appear to face criminal charges filed against them over the drug trial.
Pfizer has reportedly told local newspaper the Nigerian Tribune that the arrest of Dogunro was "unlawful" and branded the other arrest warrants as "improper because the defendants in the Kano criminal case were not served summonses, and thus, were not required to appear in court".
The company is now seeking to have the arrest warrants overturned.
The drug giant vowed to "use every legal means to challenge the illegal arrest and intimidation of its former and current employees" and reiterated that while doing so it will also continue to vigorously defend itself against the allegations surrounding the trial brought by the Nigerian government.
Since May 2007 Pfizer has been pursued by both Nigeria's federal government and its Kano state government and is defending civil and criminal charges brought by both governments over the matter, who are seeking a reported total of $8.5bn (€6bn) in damages.
1996 marked the beginning of a major meningitis epidemic in Nigeria which killed almost 12,000 children over a six-month period and Pfizer claims, in a statement of defence, it set up the Trovan study at the Infection Disease Hospital (IDH) in Kano, in northern Nigeria, with the objective of bringing to that country "a life saving, innovative, less painful and cost-effective form of antibiotic to treat epidemic meningococcal meningitis."
According to Pfizer, the clinical study involved 200 children in Kano, after the area suffered the meningitis outbreak, and half of the patients received Trovan while the other half received a dose of an already approved meningitis treatment, Roche 's Rochephin (ceftriaxone).
Prior to this, Trovan had already been tested in 5,000 patients elsewhere.
However, according to an article in the Washington Post in May last year, the drug had never before been tested in children with meningitis and Nigerian officials are claiming in the lawsuit that Pfizer's actions resulted in "the deaths of 11 children and left others deaf, paralysed, blind or brain-damaged".
Currently, the drug is not marketed in Europe and is only available in the US for adults, although its use is restricted due to its reported association with liver toxicity and deaths.
The Nigerian government also alleges that Pfizer failed to obtain all the required approvals for the trial and did not get proper consent from the patients' families.
Pfizer denies every material allegation and issued a statement last year claiming it did not misrepresent or conceal any facts in its decision to come to Nigeria, adding its intention "was clear from the beginning".
Furthermore, Pfizer said that before conducting the Trovan clinical study in Kano, it "sought and obtained all necessary approvals from relevant federal and state government agencies in Nigeria," and has more than 12 letters between the company and the US and Nigerian regulators discussing and approving the study.
The scandal around the Trovan trial resurfaced when in 2001, the Nigerian Ministry of Health appointed a panel of experts to look into the 1996 trial.
However, according to Pfizer, the resulting report was never made public until an article in the Washington Post reported excerpts from it last year.
The health committee report concluded that Pfizer's actions violated Nigerian law, the international Declaration of Helsinki and the UN Convention on the Rights of the Child.
Nigeria subsequently brought a previous lawsuit against Pfizer in a US court although this was dismissed in 2005 by a federal judge who said the case should instead be heard by a Nigerian court, where this latest lawsuit has indeed been filed.
The case highlights the potential minefield pharmaceutical companies are entering as they increasingly conduct drug testing in the developing world, especially in regard to informed consent.