A Cymbalta withdrawal study by Eli Lilly and Co, the maker of Cymbalta, found that withdrawing from Cymbalta often produces severe adverse effects that continue for weeks following discontinuation of the drug.
The investigators looked at nine previous trials (studies that test the effectiveness and side effects of drugs) in which patients had been abruptly withdrawn from Cymbalta. Six were short term (8-9 weeks) studies and three were long term (two lasting 34 weeks, one lasting a year). Each Cymbalta withdrawal study was funded, designed and conducted by Eli Lilly and Co.
In the short term trials, 44.3% of the patients treated with Cymbalta experienced one or more withdrawal effects. In a large trial included in the Cymbalta withdrawal study involving 1,279 patients, 51% experienced withdrawal symptoms. The most common were:
Paresthesia (this includes electric shock sensations in the brain)
Approximately 51% of the adverse withdrawal reactions reported were moderate; nearly 10% were severe. Following a one-to-two week withdrawal period, the adverse reactions had not resolved in 54% of patients.
In the longer term studies, the incidence of severe reactions ranged from 3% to 17% of the reactions reported by patients. In these studies, adverse reactions failed to resolve in 55% – 64% of patients within two weeks.
There is good reason to suspect that the Cymbalta withdrawal study actually underestimated the frequency, severity and duration of Cymbalta’s withdrawal effects. First, Lilly did not use a questionnaire to monitor withdrawal reactions in the clinical trials. Had Lilly done so, as the authors themselves admit, it might have produced higher incident rates. Additionally, this Cymbalta withdrawal study, as well as the nine drug trials from which this study gathered its data, were all funded and conducted by Eli Lilly and Co. Research has consistently shown that studies sponsored by a drug company are more likely to present a positive view of that company’s product. See, for example, December 2012 study published in the highly respected Cochrane Database of Systematic Reviews. A 2007 study published in the British Journal of Psychiatry found that this is particularly true of psychiatric drug studies. Investigators compared drug trials in three major psychiatric journals and concluded, “Independent studies were more likely to report negative findings than industry-funded studies.” The authors also found that the involvement of a drug company employee had an even greater effect on study outcomes than drug company sponsorship. Three of the researchers in this Cymbalta withdrawal study were Eli Lilly employees.
It is significant that the researchers only followed patients for one to two weeks following discontinuation of the treatment.
The Cymbalta withdrawal study gives no information on what happened to the patients after two weeks.
David G. Perahia1,2; Daniel K. Kajdasz3; Durisala Desaiah3; Peter M. Haddad4
Lilly Research Centre, EMC Building, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, UK
The Gordon Hospital, London SW1, UK
Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
Neuroscience and Psychiatry Unit, University of Manchester, UK
Journal Journal of Affective Disorders, 2005 Jan 1;89:207-212.
Funding This work was supported by Eli Lilly and Company, Indianapolis, IN, USA. David Perahia, Daniel Kajdasz, and Durisala Desaiah are employees of Eli Lilly and Company. Peter Haddad has received payment from Eli Lilly and Company and other pharmaceutical companies for attending advisory boards, lecturing and consultancy work.