Preventability of adverse effects of analgesics: analysis of spontaneous reports.

Objectives: The aims of this study were to determine the patterns of analgesic adverse drug reactions (ADRs) and to assess their preventability and contributing factors.

Methods: This is a retrospective, descriptive study conducted on ADRs of analgesics and other drugs indicated as analgesics, spontaneously reported to the Bordeaux pharmacovigilance center from January 2011 to June 2012.

Results: The 141 cases selected for the analysis included 16 cases of medication errors (11.3%) and 15 addiction cases (10.6%). In total, 214 ADRs were registered, for which 173 analgesic medicines were suspected. The most frequent ADRs reported were nervous system disorders (26.6%), psychiatric disorders (15.0%), and skin and subcutaneous tissue disorders (12.1%). Tramadol alone or in combination (17.3%), followed by morphine (15%), fentanyl (9.8%), and paracetamol (8.7%) were the most frequently involved analgesics. More than half of the cases (54.6%) were serious and led to hospitalization or prolonged hospitalization. Preventability was determined for 134 cases (95%): 51.5% were considered as preventable, 26.1% not preventable, and 22.4% not assessable. The main contributing factors for the preventable cases included negligence of recommendations for analgesic use and failure to consider patients' risk factors when prescribing.

Conclusions: A significant number of analgesic ADRs could be prevented, and being aware of their contributing factors promotes efficient analgesia with minimum risks to the patients.