PHARMACOEPIDEMIOLOGY AND PRESCRIPTION Pharmacoepidemiological characterisation of zolpidem and zopiclone usage Caroline Victorri-Vigneau & F. Feuillet & L. Wainstein & M. Grall-Bronnec & J. Pivette & A. Chaslerie & V. Sébille & P. Jolliet Received: 18 April 2013 / Accepted: 1 July 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Purpose Zolpidem and zopiclone are two widely used non- benzodiazepine hypnotics whose usage seems to be associated to pharmacodependence. However, to our knowledge, there has as yet been no published epidemiological study which has compared their abuse or dependence potential. We used a pharmacoepidemiological approach to identify and character- ise zolpidem and zopiclone users in real life situations. Methods Regular users of zolpidem or zopiclone were iden- tified in the database of a French regional health insurance organisation. A latent class analysis (LCA) was used to iden- tify different subgroups of users of these two hypnotics. Results The study cohort comprised 25,168 patients who regu- larly used zolpidem and 21,860 who regularly used zopiclone. The results of the latent class analysis, which enables subgroups with similar patterns of response to be identified, revealed four clinical subtypes of users of zolpidem: non-problematic users, users with associations with hypnotics/anxiolytics or with asso- ciated mental disorders, and problematic users. Only three sub- groups were identified for zopiclone, and LCA did not discrim- inate a special class of problematic users for this drug. Conclusion Our analysis indicates that there is a subclass of zolpidem user suggestive of abuse; this was not the case for zopiclone. This methodology is very interesting because it allows analysis of databases and determination of a specific signature of drugs potentially leading to abuse or dependence. Keywords Zolpidem . Zopiclone . Pharmacodependence . Abuse . Pharmacoepidemiology Introduction Zolpidem and zopiclone are non-benzodiazepine hypnotics which bind to the benzodiazepine binding site on the gamma- aminobutyric acid-A receptors. These drugs are short-acting hypnotics which are clinically effective, safe and well tolerated, and they also have favourable pharmacokinetic profiles for use as hypnotics (rapidly absorbed and eliminated); all of these properties have contributed to their popularity. They have the same indications: occasional or transitory insomnia. They are thought to be safer drugs than benzodiazepines based on the results of initial clinical trials which reported no evidence of abuse or dependence potential [1]. To the contrary, the World Health Organisation (WHO) considered that the frequency of zolpidem abuse and depen- dence is similar to that of benzodiazepine and on July 15 2002 transferred zolpidem, but not zopiclone, to the list of Schedule IV drugs of the 1971 Convention (for drugs which induce dependence, similar to benzodiazepines) [2, 3]. In France, the package information for zolpidem and zopiclone was com- prehensively modified by the health authorities in 2004. Spe- cifically, this information for both drugs now includes the C. Victorri-Vigneau : L. Wainstein : P. Jolliet Department of Clinical Pharmacology, Center for Evaluation and Information on Pharmacodependence, Nantes University Hospital, Nantes, France C. Victorri-Vigneau : F. Feuillet : L. Wainstein : M. Grall-Bronnec : V. Sébille : P. Jolliet EA4275 Biostatistics, Pharmacoepidemiology and Subjective Measures in Health Science, Nantes University, Nantes, France F. Feuillet : V. Sébille Biometric Platform, Nantes University Hospital, Nantes, France J. Pivette : A. Chaslerie Regional Department of Health Insurance Medical Service of Pays de la Loire, Nantes, France C. Victorri-Vigneau (*) Service de Pharmacologie Clinique, Institut de Biologie, 9, quai moncousu, 44093 Nantes cedex, France e-mail: caroline.vigneau@chu-nantes.fr Eur J Clin Pharmacol DOI 10.1007/s00228-013-1557-x