Calcium Channel Blockers Co-prescribed with Loop Diuretics: A Potential Marker of Poor Prescribing?

Prescribing cascades are where a drug adverse reaction is wrongly attributed to the emergence of a new condition, which leads to further drug prescribing. This promotes polypharmacy, adverse drug reactions and therapeutic burden. An example of a prescribing cascade is the co-prescribing of loop diuretics to treat the peripheral oedema caused by calcium channel blocker (CCB) drugs. Although well recognised, this is still a combination of medications taken by millions of people worldwide. CCBs have no prognostic benefit in heart failure and have an absolute risk increase for oedema of around 8-18% (number needed to harm 6-13). In the treatment of hypertension, they also increase the risk of oedema and a new diagnosis of heart failure without having any major advantages over alternative drugs. The best way to manage the oedema caused by CCBs is to switch to an alternative medication. Only where this is not possible or fails to achieve therapeutic goals would the CCB-loop diuretic combination appear to be justified. In many cases, therapeutic practice could be improved by targeting people on CCB-loop diuretic combinations for medication review. This could improve quality of life and reduce polypharmacy, adverse drug reactions, therapeutic burden and financial costs for millions of people worldwide.