The Weber-curve pitfall: effects of a forced introduction on reporting rates and reported adverse reaction profiles
- 154 Downloads
Background: In May 1999 Losec® MUPS (MUPS) were granted a marketing authorisation in the Netherlands, followed by the withdrawal of the Losec® capsules (capsules) in September 1999. Both formulations contain omeprazole as active substance. This forced switch resulted in a large number of spontaneous reports of adverse drug reactions (ADRs) to the Netherlands Pharmacovigilance Centre Lareb.Methods: We calculated and compared the reporting rate of both formulations and grouped the reported adverse reactions into system and organ classes (SOCs) in order to analyse possible differences in the type of reported ADRs.Results: Lareb received 480 reports on omeprazole formulations between May 1997 and December 2000. A quarter of the reports concerned a decrease in therapeutic effect. The reporting rate on MUPS showed a sharp rise after withdrawal of the capsules, but did not differ significantly from the reporting rate on the capsules. A comparison of the type of reported ADRs showed differences in six SOCs. Elimination of the reports concerning a decreased therapeutic effect reduced the number of different SOC reporting rates. Certain gastrointestinal complaints were reported more frequently as an ADR of MUPS.Conclusion: The forced switch caused an increase in reports resembling an early Weber effect rather than a decrease in safety of the newer formulation. However, our analysis cannot exclude differences in pharmacokinetic, pharmacodynamic or safety characteristics.
Unable to display preview. Download preview PDF.
- 1.College voor zorgverzekeringen. Farmacotherapeutisch Kompas 2000/2001. Utrecht, The Netherlands: Roto Smeets 2000.Google Scholar
- 2.Nefarma. Repertorium 1998/1999. The Hague, The Netherlands: SDU Service-centrum Uitgeverijen 1998.Google Scholar
- 3.Katelaris PH, Phelps G. A randomised controlled comparison of omeprazole capsules and multiple unit pellet system tablets for healing ulcerative oesophagitis. Aust Gastroenterology Week 1999; 14: A113 (Suppl) (Abstract).Google Scholar
- 4.Anderberg EK. Bioequivalence between omeprazole MUPS® tablets and omeprazole capsules. Gastroenterology 1998; 114(4): A56 (Abstract).Google Scholar
- 5.Broekmans AW, Lekkerkerker JFF, Koning de GHP, Vree PH. Nieuwe regels voor het melden van bijwerkingen in Nederland na 1995. [New rules for the reporting of adverse drug reactions in the Netherlands.] Ned Tijdschr Geneeskd 1996; 140(22); 1166–7.Google Scholar
- 6.Weber JCP. Epidemiology of adverse reactions to nonsteroidal antiinflammatory drugs. In: Advances in Inflammation Research, Volume 6. New York: Raven Press, 1984.Google Scholar
- 7.Anonymous. WHO Adverse Reaction Dictionary. Uppsala, Sweden: WHO Collaborating Centre for International Drug Monitoring, 1995.Google Scholar
- 8.De Craen AJM, Roos PJ, De Vries AL, Kleijnen J. Effect of colour of drugs: systematic review of perceived effect of drugs and of their effectiveness. BMJ 1996; 313: 1624–6.Google Scholar