Mumbai: The Nigerian government has filed charges against Pfizer, the world''s largest pharmaceutical multinational and the maker of male anti-impotency drug Viagra, accusing it of carrying out drug trials for its anti-meningitis drug Trovan without approval from the Nigerian government, demanding $7 billion in damages from the US company.

Pfizer, which said the trials were conducted according to Nigerian and international law, had tested the experimental antibiotic Trovan in Kano, in Northern Nigeria, during an outbreak of meningitis in 1996, prior to its approval by the US FDA in 1997.

Some 200 children are said to have died while others developed mental and physical deformities as a result of side effects after the drug was administered to them.

The US Food and Drug Administration (FDA) had approved Trovan, also known as Trovafloxacin, to treat a broad range of infections. However, its use was severely restricted in 1999 after being linked to several cases of liver failure.

The Nigerian government is claiming $7 billion in damages for the families of children who died or suffered debilitating side effects after being administered Trovan, as part of Pfizer''s drug trials.

The state government of Kano, where the trials were conducted, had filed separate charges against Pfizer earlier in 2005, seeking $2.7 billion on behalf of the families.

While the Nigerian government says the children were injected with the drug without approval from Nigerian authorities, a Pfizer spokesman reiterated the company''s position that the trials were conducted with the full knowledge of the Nigerian government.

Previous lawsuits

This is not the first time the drug multinational has found itself being litigated against over the 1996 drug trials in Kano, though this is the first time that the Nigerian government has moved against it.

While the case filed by the Kano state government has been going on for two years, in 2001 the drug firm faced legal action from individual families following the deaths and health problems suffered by children. Pfizer was then already facing two class-action lawsuits and a government investigation in Nigeria over the Trovan trials.

This suit had alleged that the drug was given in a form never before tested on humans and which was known to have life-threatening side effects. It alleged that some children in the test group were given low doses of a control drug known to be an effective meningitis treatment and approved by the FDA.

The suit alleged that the low dosages resulted in six deaths among the control group, allowing Pfizer to claim Trovan was effective, possibly more so than other drugs in the market.

It further alleged that Pfizer did not tell parents they were free to refuse the drug and instead choose an internationally approved treatment for meningitis being offered at the same site free of charge by charitable medical group Medicines Sans Frontiers (MSF).

As the death toll mounted during the 1996 outbreak of meningitis, the state radio broadcast instructions to families to take sick children as quickly as possible to the Infectious Diseases Hospital, where MSF was providing free emergency treatment. What the radio did not say was that Pfizer was also at the hospital, conducting tests on Trovan.

Many parents unwittingly allowed the Pfizer team to test the drug on their children mistaking it to be part of the MSF.

The lawsuit, filed by the families in a US district court in August 2001, also charged that Pfizer had neither obtained parental consent, nor had it explained to them that the proposed treatment was experimental.

Pfizer had then stated that it had obtained verbal consent from the parents.

It was also alleged that when the epidemic broke out, Pfizer representatives travelled to Kano to test the experimental drug. "But rather than making the trip to provide humanitarian relief, as charitable organisations were doing, Pfizer hurried to Kano to exploit the misfortune there for its own benefit," the suit alleged.

When these allegations first surfaced, Pfizer had said that the number of deaths in the trial was lower than the overall fatality rate for the meningitis epidemic. The company stressed the trial was not an attempt to gather clinical data, but an effort to help affected children in a poor region of Nigeria.

Pfizer said it did not get written consent from those involved in the tests, because it was dealing with illiterates, but said its staff did explain what they were doing and that the drug had already been tested in America.

It also claimed having received a letter of authorisation from the ethics committee of Kano''s teaching hospital, dated March 1996, approving the tests.

But Dr Sadiq Wali, the medical director of that hospital, told BBC in an interview in 2001 that there was no ethics committee at that time. The ethics committee in this hospital started in October 1996, that''s about six months after the tests, he had said.

Meanwhile, Trovan''s use is now severely restricted and it has been withdrawn from European and American markets after a number of patients developed serious liver problems and deaths of some patients.