Many things can impact upon how a person responds to a medicine, including gender, age, drug interactions (when the effects of one medicine are influenced by another medicine), overall health, and lifestyle. However, genetics is also an important factor in medicine response.

How do our genes impact the safety and efficacy of medicines?

Genetic variation can change how much of a medicine is absorbed, broken down, distributed and removed from the body, as well as how a medicine interacts with proteins in the body to have the intended effect. For instance, if a medicine is broken down too quickly or is too rapidly removed from the body, it may not reach therapeutic levels, resulting in reduced effectiveness. Conversely, if the drug is broken down too slowly, it may build up in the body leading to potential side effects (1).

What is Pharmacogenomics?

Pharmacogenomics is the study of how an individual’s genes effects response to medicines (safety and efficacy). Pharmacogenomic information can be used to guide the choice of treatment and dose. By prescribing medicines based on a patient’s genetics, that patient is more likely to get a treatment that is most the effective medicine for them, at the best dose, the first time they are treated (2).

Figure 1: Pharmacogenomics in clinical practice – Image Credit: Royal College of Physicians and British Pharmacological Society 2022 (2)

How are we approaching implementing pharmacogenomics at scale in the NHS?

Pharmacogenomics is a growing field, and there are several examples where pharmacogenomic testing is already benefiting NHS patients, for example:

  • DPYD and Fluoropyrimidines (3).
  • TPMT, NUDT15 and Thiopurines for patients with acute lymphoblastic leukaemia (4).
  • m.1555A>G and aminoglycoside antibiotics (5).

Specific patient testing criteria is outlined in the National Genomic Test Directory.

However, there are many more commonly prescribed medicines where pharmacogenomic-based prescribing could be used to guide medicine choice and dosing. The Pharmacogenetics Roll Out – Gauging Response to Service (PROGRESS) project led by the North West GMSA will establish the feasibility of delivering pharmacogenomic results for patients in primary care in the NHS.

The study includes four types of medicine:

  • Statins
  • Proton Pump Inhibitors
  • Selective Serotonin Reuptake Inhibitors
  • Tricyclic Antidepressants

A short animated video has been created to explain the NHS PROGRESS Study. The North East and Yorkshire are looking forward to taking part in this exciting research, as recruitment is extended across England in 2023.

Want to learn more?


1. pharmgkb. What is Pharmacogenomics? [Online] [Cited: 03 08 2023.]

2. Royal College of Physicians and British Pharmacological Society. Personalised prescribing- using pharmacogenomics to improve patient outcomes. 2022.

3. UK Chemotherapy Board. Personalised Medicine Approach For Fluoropyrimidine-based Therapies. [Online] 2020.

4. Yallop, Deborah. Guideline for 6-mercaptopurine dosing in adult acute lymphoblastic leukaemia based on TPMT and NUDT15 genotypes. British Oncology Pharmacy Association. [Online] [Cited: 04 08 2023.]

5. Medicines & Healthcare products Regulatory Agency. Aminoglycosides (gentamicin, amikacin, tobramycin, and neomycin): increased risk of deafness in patients with mitochondrial mutations. s.l. : Drug Saftey Update, 2021.