Memory loss from too many medicines.

Even though we may need more medicines as we get older, sometimes too many medicines (or too much medicine) at home can cause other problems.

Recently, I conducted a medication review for an elderly man who was taking pregabalin for “nerve” pain due to back problems in his spine from osteoarthritis.

This gentleman also had problems sleeping due to anxiety, mood and restless leg syndrome – all conditions which likely increased his perception of pain at night.

And just to make things a little more interesting, the patient just started a new drug, mirtazapine which is a used to help with mood and sleep at night in elderly people due to its sedating effects.

Like many drugs, pregabalin and mirtazapine have one very important thing in common.

The dose of these medicines must be adjusted slowly, both up and down.

This is very important because these drugs can cause CNS depression which is a slowing of brain activity that helps with problems such as anxiety, stress reactions, pain (pregabalin only) and sleep problems (insomnia).

Importantly for pregabalin,

  • The dose of pregabalin is usually adjusted slowly every 3 to 7 days, starting with 25mg at night in elderly people.
  • The maximum dose of pregabalin depends on how well the kidneys work – 150mg daily for this elderly man with a recommendation to split the dose during the day (for example,  75mg twice a day).
  • Daytime tiredness means the morning dose should probably be a little less than the night-time dose – say 25mg in the morning and 50 to 75mg at night would be fine.

And just as important for mirtazapine,

  • The dose of mirtazapine should start with 15mg at night and increase after two to four weeks to 30mg at night if needed.

So, we always increase and decrease the dose of these drugs slowly because together they may cause too much slowing and interference of brain activity which results in side effects such as  dizziness, daytime drowsiness, confusion, and loss of memory (or memory impairment)

Importantly, pregabalin and mirtazapine can increase the dampening or slowing effect on the brain, more so when taken together as compared to separately.   

What went wrong here?

One morning this man presented at the doctor’s surgery suffering from confusion and amnesia (loss of memory) – he didn’t know where he was at the time or what he was supposed to be doing there.

An ambulance was called and the gentleman was taken to hospital as the doctor thought his elderly patient (who had a history of heart disease) may be having a stroke.

Following discharge from hospital, the doctor requested a Home Medicines Review (HMR) which told the story behind what went wrong with the medicines that this elderly man was taking.

  • This patient was changing the dose of pregabalin randomly (↑ and ↓) taking 150mg that night because the pain was a bit worse, as well as the normal morning dose of 75mg
  • He also just started mirtazapine with half a tablet (or 15mg) at night but took another half tablet one hour later because he couldn’t sleep – he did not follow his doctor’s directions.
  • The maximum dose of pregabalin recommended for this man was 150mg daily (divided doses) because his kidneys (which slow down with age) could not clear the drug quick enough from the body (and his total dose for the day was 225mg!).
  • The result – drug accumulation due to less clearance by the kidneys and too much slowing of brain activity which caused adverse side effects such confusion and memory loss.

This could have been much worse for this man because he had osteoporosis and daytime drowsiness could cause a fall and fracture which is a major health hazard for the elderly in general. [In the first 12 months after a major fracture, the risk of dying increases by up to 50% for some elderly people]

So, what do change here to stop this happening again?

The following recommendations were made to the doctor and patient;

  1. All medicines to be packed in weekly pill reminder – and family support is important here. The patient’s son offered to help pack the medicines with the father in the pill box each week – this is also a good way to check at the end of each week whether or not dad has taken all his daily medicines!
  2. Only one strength of pregabalin capsules (25mg here) should be left at the house in the future! This patient had 3 different strengths of pregabalin (25,75, and 150mg) lying around at home and sometimes we may take the wrong strength of medicine accidentally because the names sound the same, the packs look similar, and our eyesight is not that good as we get older.

One thing for sure – this Home Medicines Review (HMR) shows how important it is not to have too many medicines lying around at home, and to use medicines as directed by the doctor.

Emmanuel Pippos, Consultant Pharmacist.

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Do you need a home medicines review? It’s very simple!

Remember - The Home Medicine Review is bulk billed through Medicare - it’s free to you.


1. Download and print the form.
2. Tick the boxes that you think may affect you.
3. Then make an appointment with your doctor.


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