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Cardiff Algorithm for Prescribing in PTSD

Members of the Traumatic Stress Wales team lead research looking at the effectiveness of medications in treating PTSD and found that there is good evidence to recommend the antidepressants paroxetine, fluoxetine, sertraline and venlafaxine, as well as other medications including quetiapine, risperidone, prazosin, mirtazapine, amitriptyline and phenelzine. This research helped to inform the International Society for Traumatic Stress Studies (ISTSS) treatment guidelines.

To further help doctors use this research to help people with PTSD, we developed the Cardiff Prescribing Algorithm for PTSD, available here: https://www.rcpsych.ac.uk/

INITIATING PRAZOSIN

The table below describes the doses of prazosin to be prescribed and the times it should be taken for an individual who experiences no problematic side-effects.  If problematic side-effects are experienced, a clinical decision should be taken by a doctor to determine if the dose should be kept the same, reduced or if the prazosin should be stopped.

As there is a risk of severe first-dose hypotension, the first and second doses should be taken whilst sitting on a bed just before lying down.  It is important to keep well hydrated while taking prazosin and to get up slowly – initially sitting up on the bed and then slowly standing up.  For the first two nights it is important to sit on the toilet to pass water rather than stand up.

Time

Morning

On going to bed

Days 1-2

Nil

1mg

Days 3-7

Nil

2mg

Week 2

1mg

4mg

Week 3

2mg

6mg

Week 4

2mg

10mg