Correlation between prescription of various dextropropoxyphene preparations and their involvement in fatal poisonings

In Sweden, the frequency of fatal poisoning by dextropropoxyphene (DXP) ingestion is constantly high. There are seven preparations containing DXP on the Swedish market; in three of them DXP is the sole analgesic ingredient, while four of them are combinations of analgesics. In an attempt to assess the death rate attributable to each DXP preparation on the basis of toxicological analyses, altogether 834 cases of dextropropoxyphene-related death over a 5-year period (1992-1996) in Sweden have been reviewed. The ratio between number of fatal poisonings and prescription of defined daily dose/1000 inhabitants during a 12-month period (DDD) was determined. The highest ratio, 27, was attributed to unmixed preparations. The ratio for DXP + paracetamol-related deaths was 6.3, and for DXP + phenazone, 6.4, while the lowest ratio, 2, was found among the DXP + chlorzoxazone cases. The unmixed preparations, representing 26% of all DXP prescriptions during the study years, were implicated in 62% of the DXP fatalities, a considerable over-representation. Unmixed preparations, with their higher content of DXP, may be more attractive for many consumers because of their narcotic (euphoric) effects rather than for any analgetic superiority. Another possibility is that unmixed preparations may erroneously have been regarded as safer than when combined with paracetamol, as reports of poisoning with compounds containing DXP + paracetamol have been most frequently reported, probably due to their predominance on the market.