Project 836 | Pharmacogenetic Optimisation of Primary Care Prescribing and Dispensing

Optimising Primary Care Dispensing using Pharmacogenetics: A Population-Scale Assessment of Genotype-Mismatched Medicine Use

What is this research about?

Most people carry at least one genetic variant that affects how their body processes medicines, yet NHS prescribing rarely takes this into account. This study aims to find out how often patients in England are given medicines that may be ineffective or unsafe for them based on their own genetics, a problem called “genotype-mismatched dispensing.” Understanding the scale of this problem is an essential first step towards safer, more personalised prescribing.

Why does it matter?

Adverse drug reactions cause significant harm to patients and cost to the NHS, and are a leading cause of hospital admissions. The 2025 NHS Ten Year Plan is committed to making pharmacogenomics, matching medicines to a patient’s genetic profile, a routine part of care. But to act on this commitment, policymakers first need reliable, large-scale evidence of how often genetic mismatches are actually happening in practice.

How will it be done?

The research uses data from Our Future Health, a large UK study with genetic information on around 550,000 people, now linked for the first time to NHS records of medicines actually dispensed to them. The team will focus on four well-studied genes (SLCO1B1, CYP2C9, CYP2C19, and CYP2D6) that affect how the body handles many common drugs, including antidepressants, statins, painkillers, blood thinners, and antiplatelet medicines like clopidogrel.

What will the study find out?

How common are relevant genetic variants across the population? How often are medicines dispensed in ways that conflict with established genetic guidance? Which groups (e.g. older people, certain ethnic groups, those on multiple medicines) are most affected? What are some of the key economic consequences of mismatched prescribing, and what could be saved by getting it right?

Who is involved and what happens next?

The 18-month project involves patients and the public throughout, and is led by researchers with strong NHS links. Results will be shared with NHS networks responsible for medicines and genomics, and analytic code will be published openly. The findings are intended to directly support the roll-out of routine genetic testing before prescribing, potentially benefiting millions of NHS patients.