A prescribing cascade is not “too many ” in general. It is a specific error of interpretation: a side effect of Drug A is treated as a new disease, so Drug B is added. Drug B can then cause its own side effect, and Drug C follows. The first drug may still be needed; the later ones often are not.
TIMES NATION
One pill leads to another: Study flags 24 ‘cascades’
Older Adults Caught In Web Of Prescriptions
Anuja.Jaiswal@timesofindia.com
New Delhi: One medicine can lead to another, and before you know it, you may be taking a pill to treat the side effects of another pill. A new study has identified 24 potentially inappropriate prescribing cascades in older adults, highlighting how one prescription can trigger another.
The most common cascade was iron supplements followed by laxatives, affecting 11.9% of older adults who started iron treatment. It was followed by cholesterol-lowering statins followed by pain relievers at 10.9%, and cholinesterase inhibitors followed by sleep medicines at 10.3%.
The study, published in The BMJ, analysed health records of 22.97 lakh community-dwelling older adults aged 66 years and above in Ontario, Canada. Researchers examined 65 potentially inappropriate prescribing cascades identified through an international expert consensus. Of these, 24 met the criteria used to prioritise cascades.
A prescribing cascade occurs when a side effect of a medicine is mistaken for a new medical condition and another medicine is prescribed to treat it. The second medicine can itself cause side effects, potentially setting off a chain of further prescriptions.
Dr Prasun Chatterjee, group clinical lead, department of geriatric medicine and longevity sciences, Apollo Group of Hospitals, said, “Polypharmacy, which means taking more than five medicines, has been reported in around 25% to 40% of people. While there is no precise India-specific data, it can occur in clinical practice. For example, amlodipine, a blood pressure medicine, can cause ankle swelling. If this is mistaken for a new problem, a diuretic may be prescribed. That can cause urinary urgency in older adults, which may lead to another medicine being added. That medicine can itself cause confusion and constipation.”
Cardiovascular medicines were the most prevalent drug classes starting cascades. Some cascades showed particularly strong associations, including corticosteroids followed by antipsychotics, laxatives followed by antidiarrheals and cholinesterase inhibitors followed by antiemetics.
Photo caption: The study highlights how one prescription can trigger another and add to burden of medicines
The Ontario/BMJ study behind the clipping found 24 high-priority such chains among 2.3 million people aged 66+ after experts had listed 65 possible pairs.
The core mechanism (always the same logic)
- Index drug is started for a real problem (BP, iron deficiency, dementia, pain).
- It produces an adverse effect that looks like a common illness of old age: swelling, constipation, ache, insomnia, urge to pass urine, confusion, nausea.
- That effect is not recognised as drug-related.
- A marker drug is prescribed for the “new” condition.
- The second drug adds harm (falls, confusion, dehydration, more constipation) and can start another cascade.
Older adults are primed for this because several diseases already overlap with drug effects (oedema, insomnia, confusion), many doctors are involved, and polypharmacy (often defined as 5+ medicines) is common.
Why the body does this: mechanisms of the main cascades
1. Amlodipine (or other dihydropyridine calcium-channel blockers) → ankle swelling → diuretic
Amlodipine opens arterioles more than veins. Capillary pressure in the legs rises and fluid leaks into tissue. That is redistribution, not heart-failure fluid overload. A loop diuretic (furosemide) does not fix the leak well, but it does cause peeing at night, low sodium/potassium, and dehydration. Urgency may then get an bladder drug; that drug can cause confusion and constipation — exactly the chain Dr Chatterjee described in the clipping.
Better moves: lower the amlodipine dose, switch class (ACE inhibitor/ARB), or add an ACE inhibitor (which can reduce CCB oedema), not automatically add a water pill.
2. Iron tablets → constipation → laxative
(Most frequent cascade in the study: 11.9% of new iron users.) Oral iron is poorly absorbed; unabsorbed iron hardens stool and slows the gut. A laxative follows. Overused stimulant laxatives can then cause diarrhoea — and the study also flagged laxative → antidiarrhoeal, a strong time-linked pair. Options: confirm iron is still needed, use a lower dose or alternate-day iron, dietary fibre, or treat constipation without stacking gut drugs.
3. Statins → muscle ache → painkiller
(10.9%.) Statins can cause myalgia. The ache is treated with NSAIDs or other analgesics. NSAIDs then raise BP, injure kidneys and stomach — which can trigger antihypertensives, PPIs, etc. The right first step is to ask whether the ache is statin-related, check CK if needed, switch statin or dose, not assume “new arthritis.”
4. Cholinesterase inhibitors (donepezil, rivastigmine, galantamine) → sleep / nausea / incontinence → more drugs
These dementia drugs raise acetylcholine.
- Nightmares or vivid dreams → sleeping tablet (10.3% cascade). Sedatives raise fall and confusion risk.
- Nausea → antiemetic (strong temporal link in the study). Some antiemetics are anticholinergic or dopamine-blocking and worsen cognition or cause stiffness.
- Urge incontinence → bladder anticholinergic (oxybutynin etc.). That cancels the dementia drug’s cholinergic benefit.
5. Corticosteroids → mood/psychosis or insomnia → antipsychotic
(Strongest sequence signal in the BMJ analysis.) Steroids can cause agitation, sleep loss, even psychosis. An antipsychotic is added. Antipsychotics in dementia/frailty raise stroke and death risk. The cascade is “treat the steroid brain effect with a neuroleptic” instead of tapering or timing the steroid.
6. Other well-mapped enginesFirst drugHidden effectSecond drug often addedWhy it is a poor bargainACE inhibitorDry coughCough syrupCough is drug-induced; switch to ARBThiazideHigh uric acidAllopurinol / colchicineMay be the diuretic, not primary goutNSAIDRise in BP / oedemaExtra antihypertensiveNSAID is the driverAntipsychotic / metoclopramideStiffness, tremorParkinson’s drugsTreating a drug-induced EPSSSRI/SNRIUrge symptomsOveractive-bladder drugAnticholinergic load; study saw this pair especially in men
Cascades that chain (the “web” in the headline)
A realistic longer chain:
Amlodipine → leg swelling → furosemide → night urination / incontinence → antimuscarinic → dry mouth / constipation / confusion → laxative or sleep drug.
Each step looks kind at the time. Together they produce falls, delirium, and a blister pack that no one dares to stop.
What is not a cascade
- Two drugs planned together on purpose (e.g. ACE inhibitor + diuretic for heart failure).
- Treating a true new disease that only happened to start after a prescription.
- Replacing Drug A with Drug B (a switch), not stacking.
The BMJ work calls the 24 pairs potentially inappropriate: population data show sequence and timing, not each patient’s motive. Some second prescriptions will be justified. The point is to ask the question before adding the next pill.
How to break the mechanism
At every new symptom in an older adult:
- Date the symptom against the last new medicine (including eye drops, inhalers, OTC painkillers, iron, tonics).
- Ask: Could this be the last drug?
- Prefer dose down, switch, or stop over add.
- Review the full list (the “brown-bag” review), especially cardiovascular drugs — they started the most cascades in the study.
- One prescriber should own the list; five specialists each adding one “small” drug is how cascades grow.
That is the mechanism: misread pharmacology dressed up as a new diagnosis, then treated with more pharmacology.
deemagclinic
