Older people have a substantially increased risk of postural hypotension in the first month after starting antidepressants, researchers have found.
GPs may want to monitor patients over 65 years more closely when they initiate antidepressant prescriptions, particularly those who are on many other medicines, the researchers said.
The study looked at patient records from 41,000 adults aged over 60 years who had a record of incident postural hypotension and an antidepressant prescription over an 18-year period.
An analysis showed a consistent increased risk of postural hypotension in the 28 days after any antidepressant prescription which then reduced once more.
When looked at by class of drug, the risk was highest with SSRIs with a four-fold increased risk in the first month, the team from University College London reported in the British Journal of General Practice.
It is not widely recognised within general practice that antidepressants are linked with postural hypotension, the researchers noted.
In the British National Formulary, postural hypotension is not acknowledged as a side effect of tricyclic antidepressants and is cited as an ‘uncommon’ side effect of SSRIs, they added.
Yet they found twice the risk in the first 28 days of taking tricyclic antidepressants.
The findings suggest information for prescribers needs to be updated and the risk should be included under ‘cautions’ for older people, they recommended.
Prescribers may consider monitoring for postural hypotension in high-risk patients, for example, those at risk of falls or who have co-morbid conditions such as diabetes or Parkinson’s disease, they concluded.
Speaking with Pulse, Dr Cini Bhanu, a clinical lecturer in general practice at UCL, explained that older people are most susceptible to postural hypotension at baseline due to physiological ageing but on top of this, antidepressants can cause it through inhibition of the sympathetic system and other mechanisms.
‘Drug side effects like this can also be amplified in older patients due to pharmacokinetics of the drug,’ she said.
GPs may want to consider other factors that put people at risk when initiating the drugs, she said.
‘All older adults over 65 are at greater risk of postural hypotension. The most susceptible will be those with significant polypharmacy (for example more than 10 drugs) and other conditions that increase risk, such as type 2 diabetes, Parkinson’s and hypertension.’
