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Piloerection induced by replacing fluvoxamine with milnacipran

  1. Satoko Hori1,
  2. Nobuko Matsuo3,
  3. Akiko Yamamoto3,
  4. Tomomi Hazui3,
  5. Hiromi Yagi3,
  6. Marumi Nakano3,
  7. Yuka Suzuki3,
  8. Akiko Miki1,
  9. Hisakazu Ohtani1,
  10. Yasufumi Sawada1,2,*

Article first published online: 23 FEB 2007

DOI: 10.1111/j.1365-2125.2006.02838.x

Issue

British Journal of Clinical Pharmacology

British Journal of Clinical Pharmacology

Volume 63, Issue 6, pages 665–671, June 2007

Additional Information

How to Cite

Hori, S., Matsuo, N., Yamamoto, A., Hazui, T., Yagi, H., Nakano, M., Suzuki, Y., Miki, A., Ohtani, H. and Sawada, Y. (2007), Piloerection induced by replacing fluvoxamine with milnacipran. British Journal of Clinical Pharmacology, 63: 665–671. doi: 10.1111/j.1365-2125.2006.02838.x

Author Information

  1. 1

    Laboratory of Drug Informatics, Graduate School of Pharmaceutical Sciences and

  2. 2

    Graduate School of Interdisciplinary Information Studies, The University of Tokyo, Tokyo, and

  3. 3

    Dream Pharmacy, Kusatsu-shi, Shiga, Japan

*Professor Yasufumi Sawada, Laboratory of Drug Informatics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113–0033, Japan. Tel.: + 81 3 5841 2270 Fax: + 81 3 5802 1570 E-mail: sawada@mol.f.u-tokyo.ac.jp

Publication History

  1. Issue published online: 23 FEB 2007
  2. Article first published online: 23 FEB 2007
  3. Received 12 April 2006Accepted29 September 2006Published OnlineEarly23 February 2007

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Keywords:

  • α1-adrenoceptor;
  • milnacipran;
  • norepinephrine reuptake inhibition;
  • piloerection;
  • receptor occupancy

Aims

To present a case of piloerection after replacing fluvoxamine maleate with milnacipran hydrochloride, and to analyse this effect based on receptor occupancy theory.

Methods

A 40-year-old female with a 3-year history of panic disorder was prescribed fluvoxamine 50 mg day−1 in addition to clorazepate dipotassium and sulpiride. Depression was not improved and she complained of fatigue, lack of energy and drowsiness. These symptoms worsened within a few days of an increase in the dose of fluvoxamine to 50 mg twice daily. Since an interaction between fluvoxamine and tizanidine, prescribed by another clinic, was suspected, fluvoxamine was replaced with milnacipran 50 mg day−1. Although her drowsiness improved, she complained of piloerection throughout her body. This symptom gradually abated within a week and when the dosage of milnacipran was increased to 100 mg day−1 at 2 months, no further piloerection occurred. We calculated the changes in α1-adrenoceptor occupancy by endogenous norepinephrine during treatment with the usual doses of milnacipran, fluvoxamine and imipramine by using pharmacokinetic and pharmacodynamic parameters obtained from the literature.

Results

The ratios of α1-adrenoceptor occupancy by endogenous norepinephrine during the treatment with milnacipran, fluvoxamine and imipramine to that without drug were estimated to be 7.13, 1.00 and 4.12, respectively. The α1-adrenoceptor occupancy by endogenous norepinephrine was increased in a dose-dependent manner by milnacipran, whereas fluvoxamine had essentially no effect.

Conclusions

The piloerection observed after the replacement of fluvoxamine with milnacipran in this patient appears to have been due to an increase in the α1-adrenoceptor occupancy by endogenous norepinephrine induced by milnacipran.

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