Evaluation of abuse and dependence on drugs used for self-medication: a pharmacoepidemiological pilot study based on community pharmacies in France (2009)

BACKGROUND: Drugs that can be obtained without a medical prescription in community pharmacies are used to treat minor pathologies that can easily be diagnosed by the patient. Some of these drugs contain psychoactive substances with a potential for abuse and dependence. However, there is a lack of data concerning their problematic use in a wide population.
OBJECTIVE: To explore the feasibility of a pharmacoepidemiological method to investigate misuse, non-medical use, abuse and dependence on drugs used for self-medication.
METHODS: This cross-sectional pilot study, conducted during a 2-month period (from 15 January to 15 March 2007), was based on the participation of community pharmacies in the Midi-Pyrenees region of France to collect patient data. Patients requesting one drug from a list of available drugs used for self-medication and containing psychoactive substances (codeine in analgesics, pseudoephedrine, dextromethorphan and histamine H(1) receptor antagonists [antihistamines]) were included in the study. A control group was set up that consisted of patients requesting antacid drugs. The pharmacy staff proposed to the patients that they filled in an anonymous questionnaire. The questionnaire was designed to investigate patterns of drug use and the harmful consequences of overuse (abuse). In addition, questions on lack of control over drug use were adapted from the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria for evaluation of dependence.
RESULTS: Thirty-two percent (n = 74) of the solicited pharmacies participated in the survey. Only 4.8% of the solicited patients (n = 817) refused to complete the questionnaire distributed by the pharmacy staff. The questionnaire was completed inside the pharmacy by 53.3% of the patients. The other patients took the questionnaire away from the pharmacy and 31.7% of them returned it in a prepaid envelope. The patient participation rate was 64.9%, and was higher for the psychoactive substance groups than the control group. Statistically significant differences on misuse (and/or non-medical use), abuse and dependence were obtained between the codeine and antacid groups. In the codeine group, among the patients having used the product in the previous month (n = 53), 15.1% misused the drug and/or used the drug for a non-medical reason, 7.5% were cases of abuse and 7.5% presented criteria of lack of control over drug use related to dependence on the substance for the psychoactive effects or for pain relief.
CONCLUSION: The results obtained in this pilot study indicate that using anonymous self-administered questionnaires offered to patients by pharmacy staff is a reliable method to obtain information on the problematic use of drugs containing psychoactive substances purchased in a pharmacy for self-medication.