Adverse drug reactions and differential diagnosis
Hopefully what should be clear by now is that you should consider adverse drug reactions as part of the differential diagnosis of any newly presented condition. You should look out for drug-induced effects – drugs causing ADRs that might be mistaken for the symptoms of a new condition.
The following activities are designed to make you think about ADRs as part of your diagnosis. Try each, using the BNF or electronic BNF to assist you when necessary. Make a note of your answers before you check them against the answers given at the end of the chapter so you can test/reinforce your own knowledge.
ADRs and differential diagnosis
An 82 year old woman arrives at the Emergency Department by ambulance, having collapsed in a supermarket. She has hypertension and angina.
She is currently taking amlodipine 5mg once daily, bendroflumethiazide 2.5mg daily, isosorbide mononitrate 20mg each morning and lunchtime, prednisolone 2.5mg one daily , alendronic acid 70mg once weekly and Adcal D3 two daily.
Which of her drugs could have contributed to her presenting complaint?
Activity
There are many reasons for this woman's collapsed but postural hypotension is a common side effect of isosorbide mononitrate and bendroflumethiazide and needs to be considered as part of the overall diagnosis. Note that, in the BNF, when you look up the side effects of isosorbide mononitrate, you are guided to side effects under glyceryl trinitrate. The side effects are shown in order of their frequency, so postural hypotension is the most common. For bendroflumethiazide it has also been reported frequently. It is also worth considering an adrenal crisis due to withdrawal of steroids although the dose in this case is quite low and may not be enough to supress the hypothalamic-pituitary-adrenal axis. A sudden withdrawal of long term steroids can be very dangerous.
Copyright eBook 2019, University of Leeds, Leeds Institute of Medical Education.