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Prevention of harm with alfacalcidol preparations | Signal

Reference number
Issue date29 September 2011


This signal is about the risks involved with the prescribing, dispensing, administration and monitoring of alfacalcidol preparations.


A sample incident reads:


“A patient was prescribed alfacalcidol. She was found to have low calcium levels. As far as I am aware from her mother and carers, the patient never had regular blood tests for calcium levels.  She now has renal failure which may have been caused by her alfacalcidol treatment.”


Alfacalcidol belongs to a group of medicines called vitamin D analogues. It is used to treat diseases where the amount of calcium requires changing. It is available in oral capsules, drops and injection. The usual adult dose is 250 nanograms to one microgram daily although higher doses are sometimes necessary.


A search of incidents reported to the National Reporting and Learning System (NRLS) between January 2008 and December 2010 identified 341 relevant medication incidents; two were associated with severe harm, two with moderate harm and the remainder with no or low harm.


Incident themes include:


•    Failure to monitor plasma calcium levels (these should initially be checked once or twice weekly and whenever nausea and vomiting occurs; when the dose is stabilised, measurements may be taken every two to four weeks);

•    incorrect frequency administered (e.g. alfacalcidol prescribed three times a week, given three times a day);

•    incorrect strength prescribed, dispensed or administered due to confusion over micrograms and nanograms in capsules (e.g. 250 micrograms prescribed instead of 250 nanograms);

•    incorrect product selection during dispensing and administration due to similar packaging; 

•    administering wrong oral liquid doses caused by confusion with the product strength (2 micrograms/ml; one drop contains 100 nanograms).


NHS organisations should ensure that:

•    Healthcare professionals check that plasma calcium monitoring is undertaken.

•    Micrograms and nanograms are not abbreviated.

•    The use of decimals is avoided by using alternative units of measure (e.g. use 250 nanograms instead of 0.25 micrograms).

•    Care is required in selecting the correct alfacalcidol products which are labelled in micrograms with leading zeros.

•    Storage locations for alfacalcidol capsules in pharmacy dispensaries are reviewed.

•    Ways to differentiate the various strengths (e.g. a warning label or automated electronic prompts) are considered.


We would like to hear from you - please contact us with your initiatives to reduce risks in these areas.


Signals are notifications of key risks emerging from review of serious incidents reported to the NRLS and shared by the NPSA.