PsychoTropicalResearch, serotonin and serotonin syndrome research.

Path to the current page: www.psychotropical.com>>MAOIs_Blood_pressure.shtml

• Home

• Serotonin toxicity / Serotonin syndrome
  • Introduction
  • Summary
  • Spectrum Concept
  • Neuroleptic malignant syndrome
  • Moclobemide & (S)SRIs
  • The clinical picture
  • Treatment of ST
  • MOI-OA-ST
  • Mirtazapine
  • Methylene Blue

• Psychopharmacology Update Notes
  • Mirtazapine
  • Why most new antidepressants are ineffective
  • Dual action antidepressant drugs
  • Lamotrigine
  • Diet and Monoamine oxidase inhibitors
  • Monoamine oxidase inhibitors
  • Latest PUN Notes
  • Serotonin Notes

• Drug Interaction (CYP450) Information
  • Introduction
  • Overview
  • Quiz
  • Quiz Answers
  • CYP notes

• Psychopharmacology Questions Answered

• Publications

• Medico-legal opinions

• Patient Information

• Contact me
  • Contact Dr Gillman
  • Request serotonin toxicity document

MAOIs - Blood pressure

Date Created: 23/06/199   Last Modified: 06/10/2002   Last Checked: 21/10/2002

I am suspicious that a survey of psychiatrists would reveal that some think that MAOIs raise the blood pressure. MAOIs are effective hypo-tensive agents.

A substantial proportion of hyper-tensive patients who take MAOIs for their depression are able to cease whatever blood pressure treatment they were previously taking. How and why the oft quoted admonition not to use MAOIs in patients with hyper-tension arose is utterly opaque to me.

The usual pattern is for a postural drop to occur when the dose is raised to a therapeutic level. Partial or complete acclimatisation to this drop develops over one to three weeks. Regular monitoring of the lying and standing BP (this is best done immediately on standing and again after one minute) allows the dose to be adjusted without problematic hypo-tension developing. A significant but not incapacitating degree of hypo-tension indicates that the minimum therapeutic dose has been achieved.

In a small percentage of cases one sees brief spontaneous hyper-tension; this usually occurs after the second dose of the day, especially when higher doses are being used. It is very rarely high enough to constitute a significant problem (see references).

The use of local anaesthetics can cause concerns. Indirectly acting (as opposed to 'directly' acting) sympathomimetics may elevate blood pressure in the same way as tyramine. This is because they act by displacing noradrenaline from the pre-synaptic terminal in the same way as does tyramine (see other notes). 'Indirectly acting' sympathomimetics might be better termed as 'post-synaptic' agonists, they directly stimulate the post-synaptic receptor and this is not a problem like the tyramine reaction is. There may be some additive effect on blood pressure but this is unlikely to give rise to BP elevations of a degree sufficient to cause a cerebral bleed.

'Directly' acting sympathomimetics that are 'safe' are:- adrenaline and noradrenaline. So local anaesthetics with adrenaline are not likely to cause severe hyper-tension. If there is concern in a dental situation and one has to advise a dentist who may be uncertain, either of the facts or of your authority, then the option of using a non-sympathomimetic vaso-constrictor like felypressin is available. Remember that advice about analgesics (eg avoid pethidine etc.) may also be needed.

See also notes on 'serotonin syndrome'

All text ©Dr Ken Gillman MRC Psych - PsychoTropical Research®


|Return to the menu at the top of this page|