Sustained-release and immediate-release drug formulations: substitutes or different products?

Our recent publication assessed the real-life use of extended and immediate release quetiapine in patients with schizophrenia spectrum disorders and bipolar disorder in Lappeenranta. Much to the surprise of the study group, the use of extended and immediate release quetiapine differed considerably in real life.

Immediate release quetiapine was used in significantly lower doses when compared to extended release quetiapine: 328 mg vs. 542mg (p<0.001). Doses equal or below 200 mg were used by 48% and 2% of patients on immediate and extended release quetiapine, respectively. At discharge, extended release quetiapine was significantly more often used as monotherapy when compared to immediate release quetiapine (79% vs. 44%; p=0.003).

The study findings may have importance when choosing treatment comparators for health economic assessments or when assessing the effectiveness of drugs based on registry data.

More information: Taru Hallinen, Erkki Soini

References:

  • Hallinen T, Soini EJ, Granström O, Ovaskainen Y, Leinonen E, Koponen H, Hänninen K. Differential use of extended and immediate release quetiapine: A retrospective registry study of Finnish inpatients with schizophrenia spectrum and bipolar disorders. BMJ Open 2012;000915.R1. Open access.
  • Hallinen TA, Soini EJ, Granström O, Ovaskainen Y, Leinonen E, Koponen H, Hänninen K. Differential use of extended and instant release quetiapine: A naturalistic study of Finnish inpatients with schizophrenia spectrum and bipolar disorders. Value Health 2011;14:A299. Abstract.