Some medicines need more supervision than others. Warfarin requires regular INR checks, methotrexate needs blood tests to catch liver problems early and lithium has such a narrow margin between a helpful dose and a toxic one that serum levels need measuring at set intervals. When this monitoring does not happen, patients can end up in hospital, which is why getting high risk medication monitoring right is one of the most important safety tasks in general practice.
As prescribing becomes more complex and workloads increase, getting this right consistently is becoming harder for practices and PCNs.
What Counts as High Risk?
Several categories of medicine require regular monitoring beyond routine repeat prescription reviews, because missed tests can quickly lead to patient harm.
- Anticoagulants top the list. Warfarin needs INR testing to keep blood clotting in the right range, while direct oral anticoagulants like apixaban and rivaroxaban need less frequent monitoring but still require kidney function checks, particularly in older patients whose renal function may be declining.
- Disease-modifying anti-rheumatic drugs such as methotrexate and sulfasalazine can affect the liver and suppress the immune system, so patients taking these need blood tests at regular intervals. This is often monthly at first and then less frequently once results are stable, and most practices manage these under shared care arrangements with hospital specialists.
- Lithium, used for bipolar disorder, has been flagged as high risk for years. The National Patient Safety Agency issued guidance on safer lithium therapy because incident reports kept showing patients experiencing toxicity, so serum lithium levels need checking regularly along with thyroid and kidney function.
Other medicines in this category include certain antiepileptics, digoxin and some immunosuppressants, each with its own monitoring schedule that practices need to track.
What Happens When Monitoring Slips
Research commissioned by the Department of Health estimated that avoidable medication errors cost the NHS around £98.5 million per year, using up over 181,000 hospital bed days annually and contributing to roughly 1,700 deaths.
Primary care accounts for about a third of harmful prescribing errors, and the medicines most often involved in hospital admissions from medication problems include NSAIDs, anticoagulants and antiplatelet drugs. Most deaths result from gastrointestinal bleeds linked to these medicines or to warfarin.
Older patients face the highest risk because they tend to take more medicines for multiple conditions, which increases the chance of interactions and makes monitoring more important.
Why Gaps Appear
Even practices with good systems can end up with gaps in monitoring, and several things contribute to this.
Shared care arrangements between hospitals and GPs sometimes leave responsibility unclear. A consultant might start a patient on methotrexate expecting the GP to handle ongoing blood tests, but if this is not communicated properly then no one picks it up. The NHS England guidance on medication safety makes clear that practices need processes in place for monitoring high risk drugs, but knowing you need a process and having one that actually works are different things.
Patients missing appointments is another common problem, whether because they do not understand why the tests matter or because they find it difficult to attend during working hours. When a patient does not come in for their blood test, the practice has to decide whether to keep prescribing or stop a medicine the patient relies on.
Busy workloads mean overdue monitoring can go unnoticed too, and without a reliable recall system patients slip through. Results from other providers sometimes do not reach the patient record either, so if someone has bloods done at hospital and the results are not added to the GP system, the practice may not know the monitoring has happened.
Making Monitoring More Reliable
Good monitoring systems share certain features.
Written protocols for each high-risk medicine should spell out what tests are needed and how often, and staff need to know where to find these and follow them consistently. Clinical system alerts can flag when monitoring is overdue, helping prevent unsafe prescribing before it happens These work best when set to trigger before a prescription is issued so the problem gets caught at the right moment.
Regular searches help identify patients who have fallen behind. Running a monthly search for overdue monitoring then following up with those patients catches gaps before they become serious. Many practices give this task to a clinical pharmacist or pharmacy technician who can work through the list systematically.
Review dates on repeat prescriptions should link to monitoring intervals, because if a patient cannot order their next prescription until their blood test is done then you create a natural check in the system.
How Clinical Pharmacists Help
Clinical pharmacists working in practices and PCNs often take the lead on high-risk medication monitoring because they understand what each medicine requires in terms of monitoring and can design systems to make sure it happens. Structured medication reviews give pharmacists a chance to check that monitoring is up to date for patients on multiple medicines. They can also audit current performance across a practice list to identify where improvements are needed. This becomes particularly valuable at PCN level, where variation between practices can otherwise lead to uneven safety standards.
Many PCNs now work with specialist providers to access clinical pharmacist expertise without recruiting permanent staff, which lets networks put proper monitoring programmes in place while managing workforce pressures.
Getting Started
Practices wanting to improve their monitoring should begin by identifying which high risk medicines their patients are taking, since a clinical system search will produce this list fairly quickly. Check that protocols are in place and match current guidance and the Specialist Pharmacy Service publishes monitoring recommendations that help with this.
Running an audit to see how many patients are currently overdue gives a baseline to improve from and setting up a regular review process with clear responsibility for following up keeps things on track.
Reliable monitoring keeps patients safer. When practices get this right, fewer people end up in hospital from preventable medication problems.
