The health threat of new synthetic opioids as adulterants of classic drugs of abuse

Extensive scientific evidence shows that there is a broad spectrum of substances used as adulterants, whose effects on the user's health may be extremely harmful. The degree of purity of the drugs most commonly abused is highly variable depending on the region or epidemiological context. Practices of drug adulteration have been substantially evolving over the years: a significant trend has been observed in the last decade indicating a decline in the average purity of most drugs. Although the most frequent adulterants of common street drugs have long been well known, the rise of synthetic opioids has inevitably entailed gaps in knowledge in terms of the substances being used and their composition, which constitutes an even greater threat to public health.