Therapeutics and safe prescribing for MRCGP AKT

An 82-year-old woman who lives alone takes 11 regular medicines. She has fallen twice in three months. Her medicines include amitriptyline 25 mg at night for nerve pain, oxybutynin for urinary urgency, and bisoprolol. Which single action is most likely to reduce her risk of falling?

1. Reduce her anticholinergic burden, starting with amitriptyline and oxybutynin correct Correct. Both drugs are strongly anticholinergic. In older people they cause drowsiness, confusion, low blood pressure on standing and falls. Stopping or switching them is the biggest single change you can make here.
2. Start vitamin D and calcium Wrong. This helps bone health in a housebound older woman, but it does not deal with the drugs that are making her fall.
3. Add a bisphosphonate Wrong. A bisphosphonate may protect her bones if she falls, but it does not stop her falling.
4. Stop bisoprolol Wrong. It might matter if she has postural hypotension, but it may be treating a real heart problem. Check lying and standing blood pressure first, and deal with the anticholinergics before this.
5. Arrange a home hazard assessment for grab rails Wrong. This is part of a full falls assessment, but it helps less than stopping the drugs that make her drowsy and dizzy.

The point: Falls with many medicines: look first at anticholinergic drugs, sedatives and anything causing postural hypotension. A structured medication review is a real treatment, not paperwork.

Source: NICE NG249: Falls: assessment and prevention in older people and in people 50 and over at higher risk NICE · tier 1, national regulator or guidance

A 62-year-old man has newly diagnosed hypertension. He started lisinopril 10 mg daily 10 days ago. He takes no other medicines and no over-the-counter tablets. He is eating and drinking normally and has had no vomiting or diarrhoea. Before starting: creatinine 90 micromol/L (60 to 110), potassium 4.6 mmol/L (3.5 to 5.3). Now: creatinine 125 micromol/L, potassium 5.1 mmol/L. According to current national guidance, which is the most appropriate next step?

1. Add furosemide to bring the potassium down Wrong. His potassium of 5.1 mmol/L is inside the normal range. A water tablet could dry him out and make his kidneys worse.
2. Switch to losartan 50 mg daily Wrong. Losartan blocks the same hormone system and would give the same fall in kidney function.
3. Continue lisinopril 10 mg and repeat the blood tests in 4 weeks Wrong. His creatinine has risen by about 39%. NICE says a rise of 30% or more needs action. Only a smaller rise would allow him to carry on at the same dose.
4. Stop lisinopril and use a different class of blood pressure drug correct Correct. The creatinine rise is above 30% and he has no other cause, such as dehydration or an NSAID. NICE says stop the drug, or drop to a lower dose he has already tolerated. He has no lower dose, so stop it and use a drug such as amlodipine.
5. Refer urgently to nephrology and continue lisinopril until he is seen Wrong. Nothing about him needs an emergency. With a rise this size the first move is to stop the drug, not to keep taking it.

The point: Check urea and electrolytes before starting an ACE inhibitor or ARB, and again 1 to 2 weeks after starting and after each dose rise. Do not change the dose if creatinine rises by less than 30% or eGFR falls by less than 25%. If the change is larger, look for a cause such as dehydration or an NSAID. If there is none, stop the drug or return to the last tolerated dose. Stop for potassium of 6.0 mmol/L or more once other causes are dealt with.

Source: NICE NG203: Chronic kidney disease: assessment and management NICE · tier 1, national regulator or guidance

A 41-year-old woman has bipolar disorder. She has taken modified-release lithium carbonate 800 mg every morning for three years. Her earlier levels were between 0.6 and 0.8 mmol/L. She took her tablets at 8 am today and had her blood test at 10 am. The lithium level is 1.4 mmol/L. She feels well, with no tremor, vomiting, diarrhoea or drowsiness. Her medicines have not changed. Which is the most appropriate next step?

1. Reduce the dose to 600 mg and repeat the level in 1 week Wrong. A sample taken 2 hours after a dose always reads high. Cutting the dose on this result could leave her under-treated and raise her risk of relapse.
2. Stop lithium and arrange same-day hospital assessment Wrong. She has no signs of toxicity and the sample was taken far too early. Admission is for a properly timed high level with symptoms.
3. Repeat the level 12 hours after her next dose and make no dose change yet correct Correct. Lithium levels are only valid 12 hours after the last dose. A sample taken earlier is falsely high, so repeat it at the right time before touching the dose.
4. Check urea, electrolytes and thyroid function and adjust the dose by those results Wrong. Those tests are routine every 6 months. They cannot tell you whether the lithium level is a true result.
5. Accept the result and repeat the level in 3 months Wrong. If the true level were this high she would be at risk of toxicity. A properly timed repeat is needed soon, not in 3 months.

The point: Take lithium samples 12 hours after the last dose. Many people take the tablets at night and have blood taken the next morning. NICE aims for 0.6 to 0.8 mmol/L in people taking lithium for the first time, and 0.8 to 1.0 mmol/L after a relapse on the lower range. Measure levels every 3 months in the first year, then every 6 months, or every 3 months in higher-risk groups. Check urea, electrolytes, calcium, eGFR and thyroid function every 6 months.

Source: BNF: Lithium carbonate British National Formulary · tier 3, national formulary