Doi:10.1016/j.clpt.2004.07.012

Postmarketing surveillance for drug safety
System database and exposure was estimated from IMSAmerica, Ltd, data. The reporting rates of PN (per 100,000 person-years of exposure) are as follows: 25.74 for lefluno- The recent commentary by Griffin et concerning a mide, 42.02 for etanercept, 23.67 for infliximab, and 1.01 for report on peripheral neuropathy and leflunomide patients methotrexate. The reporting rate for methotrexate is consid- claims that, as of October 2003, none of the 6 postmarketing erably lower than that for the newer disease-modifying anti- studies committed to by Aventis (Bridgewater, NJ) at the time rheumatic drugs, consistent with the underreporting of events of approval had been started, at least according to a Food and that is known to occur with well-established therapies over time.
Drug Administration (FDA) database. In fact, all 6 of these Since 1998, worldwide patient experience with lefluno- studies were initiated between 1998 and 2003, and results mide has exceeded 770,000 patients and has confirmed a from completed and ongoing studies have been favorable benefit/risk profile for the treatment of adult pa- Aventis has performed many postmarketing studies in close tients with RA. Potential safety signals generated from active cooperation with regulatory authorities around the world sup- and intensive postmarketing surveillance have been further porting the positive benefit-risk profile of leflunomide.
tested and analyzed in large observational cohort studies.
The report by Bonnel and in the same issue raises Physician and patient information has been continually up- several methodologic concerns that make the interpretation of dated to reflect current knowledge about the safety of this the selective data presented difficult, especially in a rheuma- The event of interest in the report, peripheral neuropathy, has been reported during leflunomide treatment in postmar- keting experience as stated in the prescribing information.
The authors selected events in the FDA database identified as Global Pharmacovigilance and Epidemiology peripheral neuropathy occurring in patients treated with le- flunomide. Peripheral neuropathy was not defined by stan- E-mail: william.holden@aventis.com dardized criteria other than subjective physician assessmentand electrodiagnostic testing, if the latter was available. Spon- Both authors are full-time employees of Aventis.
taneous report information, the data source for this article, isoften lacking the kind of detail necessary for a complex References
diagnosis. Baseline electromyography and nerve conduction 1. Griffin MR, Stein CM, Ray WA. Postmarketing surveillance for studies were not available in these patients. This is important drug safety: surely we can do better. Clin Pharmacol Ther 2004; because peripheral neuropathy is a common manifestation in the RA Subjective improvement appears to be 2. Silverman E, Prieur A, Spiegel LK, et al. Efficacy and safety of leflunomide (LEF) versus methotrexate (MTX) in the treatment of the outcome measure, because no electromyography or nerve pediatric patients with juvenile rheumatoid arthritis. Ann Rheum conduction study results were noted after drug discontinua- tion. Reasons for drug discontinuation were also not pro- 3. Wolfe F. Low rates of serious liver toxicity to leflunomide (LEF) vided. Information regarding symptom time to onset was and methotrexate (MTX): A longitudinal surveillance study of noted to be lacking in 42% of the reports; however, the 14,997 LEF and MTX exposures in RA. Arthritis Rheum 2002; Kaplan-Meier curve in Fig 1 of the report of Bonnel and shows the time to onset of symptoms in reports on 4. Kremer JM, Genovese MC, Cannon GW, Caldwell JR, Cush JJ, all 80 patients after the start of leflunomide therapy.
Furst DE, et al. Concomitant leflunomide therapy in patients with It is problematic that the authors selected anakinra as the active rheumatoid arthritis despite stable doses of methotrexate: arandomized, double-blind, placebo controlled trial. Ann Intern comparator, a drug launched 3 years after leflunomide and one with significantly lower exposure. An estimation of re- 5. Bonnel RA, Graham DJ. Peripheral neuropathy in patients treated porting rates through June 2003 (the latest date for which data with leflunomide. Clin Pharmacol Ther 2004;75:580-5.
are available) with the use of disease-modifying antirheu- 6. Rosenbaum R. Neuromuscular complications of connective tissue matic drug comparators with similar or greater patient expo- disease. Muscle Nerve 2001;24:154-69.
sure is presented here. The numbers of cases of peripheralneuroathy came from the FDA Adverse Event Reporting

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