LAGOS, Nigeria (CNN) -- Nneka and Chimezie Ononaku unwittingly poisoned their own four-month-old son Chinonso.

A television image of Chinonso Ononaku, who died after being given the medicine "My Pikin."

Giving him what they thought was a baby teething medicine, they were in fact dosing him with anti-freeze.

The bottle had been contaminated with a toxic chemical called diethylene glycol.

More than 30 Nigerian children are thought to have died recently after taking the medicine.

Nneka is angry.

"It's not easy carrying a pregnancy for nine months, [and] after that getting a drug from a pharmacy to kill your own child," she says.

When Nigeria's Agency for Food and Drug Administration and Control (NAFDAC) tested the medicine, "My Pikin," the results were terrifying.

It found the medicine contained almost 90ml of diethylene glycol per 100ml.

"It's a bottle of poison," the NAFDAC laboratory said.

The "My Pikin" factory's managing director and eight others have been charged with negligence. The company could not be reached for comment.

Nigeria is on the frontline in the global fight against counterfeit drugs.

Undercover NAFDAC officers have taken to the streets in order to combat unregistered and often harmful drugs. Hawkers are charged with selling counterfeit drugs and forced to pay a fine. Watch more on the poisonings »

NAFDAC claims most of the counterfeit drugs come from India and China.

And it's big business -- America's Centre for Medicines in the Public Interest predicts counterfeit drug sales will reach $75 billion in 2010.

NAFDAC's director-general Dora Akunyili warns counterfeiting is not just a Nigerian problem.

"These criminals are cooperating, so we too need to cooperate if we can face them. Not only in Nigeria but internationally, because drug counterfeiting involves a trans-national criminal network and can only be dismantled through international co-operation."