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Drug evaluation: an ongoing process

Evaluating a drug does not simply involve applying for a marketing authorisation: confirmation of data at a later stage is needed.

In the 1950s, thalidomide was used as a sedative. When given to pregnant women, it caused very severe foetal malformations. Babies were born with phocomelia, i.e. without arms or legs, their hands and feet attached directly to their bodies.

Thalidomide was withdrawn from the market, but there has been a growing interest in this drug as a treatment for myeloma. In 2008, it was granted a marketing authorisation as first-line treatment for myeloma in elderly patients. This authorisation relied heavily on two clinical trials. The results of the first trial showed an increased survival rate of around 18 months. The interim results of the second trial tended to confirm this. But the full results ultimately did not show any real increase in survival. And when the results of three other trials were eventually published, only one trial showed an increased survival rate. The initial enthusiasm evaporated, even though thalidomide represents a benefit for some patients.

The granting of a marketing authorisation is based on a gamble that the initial evidence will subsequently be more or less substantiated. This gamble requires the drug regulatory authorities to demand at least one confirmation trial, in order to better protect patients.

©Prescrire February 2009

Source: "Pari" Rev Prescrire 2009; 29 (303): 5.

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