The effects of St. John's wort extract and amitriptyline on autonomic responses of blood vessels and sweat glands in healthy volunteers.
St. John's wort extract is widely used and advertised as a "natural antidepressant" lacking autonomic side effects. This randomized, double-blind, placebo-controlled study compared the effects of St. John's wort extract on autonomic responses of blood vessels and sweat glands with those of amitriptyline and placebo. A randomized, double-blind, crossover study was performed in healthy male volunteers aged 22 to 31 years (25 +/- 3 years; mean +/- SD) years. Subjects orally received capsules with 255 to 285 mg St. John's wort extract (900 microg hypericin content), 25 mg amitriptyline, and placebo 3 times daily for periods of 14 days each with at least 14 days between. Vasoconstrictory response of cutaneous blood flow (VR) and skin conductance response (SR) following a single deep inspiration were employed as parameters of autonomic function. St. John's wort extract had no effect on VR and SR. In contrast, SR was diminished and the dilation phase of VR was prolonged following multiple dosing with amitriptyline (P < 0.05). Decreased electrodermal reactivity observed with amitriptyline reflects inhibition of acetylcholine at peripheral m3-cholinoreceptors, whereas prolongation of VR induced by the tricyclic drug may be due to sustained activation of central and/or peripheral sympathetic neurons.
Siepmann
Martin
M
Institute of Clinical Pharmacology, Medical Faculty, Technical University, Dresden, Germany. Martin.Siepmann@mailbox.tu-dresden.de
Kirch
Wilhelm
W
Krause
Stephanie
S
Joraschky
Peter
P
Mueck-Weymann
Michael
M
D000284:Administration, Oral; D000328:Adult; D000639:Amitriptyline / Q000494:pharmacology* / Q000627:therapeutic use; D000928:Antidepressive Agents / Q000494:pharmacology / Q000627:therapeutic use; D001341:Autonomic Nervous System / Q000187:drug effects / Q000502:physiology*; D001808:Blood Vessels / Q000187:drug effects* / Q000294:innervation / Q000502:physiology; D002214:Capsules; D018592:Cross-Over Studies; D003866:Depressive Disorder / Q000188:drug therapy; D004334:Drug Administration Schedule; D005712:Galvanic Skin Response / Q000187:drug effects / Q000502:physiology; D005858:Germany; D006801:Humans; D020902:Hypericum; D008297:Male; D008517:Phytotherapy; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D012867:Skin / Q000098:blood supply / Q000187:drug effects; D013545:Sweat Glands / Q000187:drug effects* / Q000294:innervation / Q000502:physiology
D000928:Antidepressive Agents; D002214:Capsules; D010936:Plant Extracts; D000639:Amitriptyline