Disproportionately high rate of epileptic seizure in patients abusing dextropropoxyphene

Dextropropoxyphene (DPP), a weak opioid, is often abused as a psychoactive substance. In this retrospective chart review to document, characterize and put in perspective the often-obtained history of epileptic seizures in patients with DPP abuse, we analyzed the case files of all patients with DPP abuse registered in our center (a tertiary-care drug de-addiction clinic in north India) from May 1, 2001 until April 30, 2007 and those with use of other opioids during the same period. Non-drug-related seizures were excluded from analysis. Out of 312 patients with DPP abuse, 63 (20.2%) had epileptic seizures related to DPP use, in contrast to 0.4% -4.2% of other opioid users. The seizures were mostly characterized as generalized tonic-clonic seizures (87.3%), occurring around two hours following a higher-than-usual dose of DPP. Those with seizures had significantly greater duration of DPP use and higher rates of medical comorbidity compared to patients without seizure. Age, duration of use and medical comorbidity were better predictors of seizure than dosage of drug or use of multiple drugs. Thus, DPP-induced epileptic seizures are common (one in five), and much more frequent than seizures in patients using other opioids. The awareness of this phenomenon has implications for diagnosis and management, as well as for drug regulation policy.