Piloerection induced by replacing fluvoxamine with milnacipran

Satoko Hori, Nobuko Matsuo, Akiko Yamamoto, Tomomi Hazui, Hiromi Yagi, Marumi Nakano, Yuka Suzuki, Akiko Miki, Hisakazu Ohtani, Yasufumi Sawada

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)665-671
Number of pages7
JournalBritish journal of clinical pharmacology
Issue number6
Publication statusPublished - 2007 Jun
Externally publishedYes


  • Milnacipran
  • Norepinephrine reuptake inhibition
  • Piloerection
  • Receptor occupancy
  • α-adrenoceptor

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)


Dive into the research topics of 'Piloerection induced by replacing fluvoxamine with milnacipran'. Together they form a unique fingerprint.

Cite this