A prior agreement on human trafficking for the purposes of crime:

Currently, the UNODC works with under the United Nations Convention against Transnational Organized Crime when it is working to address the trafficking of humans for the purposes of drug trafficking and drug-related crime. One protocol of the convention is the Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women and Children. This is an essential part of any agreement on transnational organized crime, such as the narcotics trade, as these people are often trafficked into a nation on the pretense of providing them with a better life, then the people who assisted them with their illegal immigration will exploit the debt (perceived or true) to force these people to commit crimes, for example selling or transporting drugs, on their behalf.

This convention is particularly beneficial to the victims of these crimes, as it aims both to prevent trafficking from occurring, and to protect and assist the victims of trafficking This means that states that are party to the convention cannot punish victims of trafficking for having been trafficked. The definition of human trafficking in the convention, "the recruitment, transportation,transfer, harbouring or receipt of persons, by means of the threat or use of force or other forms of coercion, of abduction, of fraud, of deception, of the abuse
of power or of a position of vulnerability or of the giving or receiving of payments or benefits to achieve the consent of a person having control over another person, for the purpose of exploitation," makes it clear that the states that are party to the convention believe that individuals who have been trafficked are victims, which is shift from some previously accepted definitions that stated that people who have been trafficked with complicit in the crimes.

You can check your nation's support of this convention and the trafficking of persons protocol on the summary of signatures and ratifications as at September 29, 2010.

Also of interest on this topic, there is a charity in the UK that works with female victims of human drug-related trafficking. They have the text of an interview about human drug trafficking on their website.