Does the time you take your medicine matter?

Hands together holding blood pressure pills

Could changing the time of day you take blood pressure medications improve their effectiveness? Professor Tom MacDonald tells Thembi Nkala how he intends to find out.

High blood pressure (hypertension) affects one in four adults in the UK. Having high blood pressure, persistently equal to or above 140/90mmHg, significantly increases your risk of cardiovascular disease, including heart attack and stroke. Hypertension, which is increasingly common with age, poses a significant threat to the health of millions of people but, once diagnosed, can be managed well with medications.

Now, a team of top researchers from across the UK, led by Professor Tom MacDonald and backed by a BHF research grant worth more than £1m, aims to find out if taking blood pressure tablets in the morning or the evening has more of an impact on your cardiovascular health.

Why might the time of day matter when taking your blood pressure medications?

The purpose of our research is to establish whether night-time dosing is better (or worse) than morning treatment

We know that taking blood pressure tablets in the morning is beneficial in controlling high blood pressure, but more recent findings (enabled by the use of 24-hour blood pressure monitoring) suggest that night-time dosing may have an even better effect. Patients with hypertension whose blood pressure dips during the night tend to experience fewer cardiovascular events compared with those whose blood pressure barely decreases. Essentially, those with constant high blood pressure day and night don’t do so well.

The purpose of our research is to study patients taking once-a-day blood pressure medication and establish whether night-time dosing is better (or worse) than morning treatment in preventing events such as heart attacks, stroke and deaths related to diseases of the heart and circulation. Participants will be randomly allocated into two groups; one will take their blood pressure tablets at night, while the other group takes theirs in the morning.

When should I take my blood pressure medication?

Currently, there is no set guidance on when you should take your blood pressure tablets. What is important is that you take them regularly as your doctor has recommended for you.

Can you tell us about the recruitment process for this study?

Recruitment to the study is open to anyone who takes tablets for blood pressure once daily. We hope to recruit more than 10,000 participants of as varied demographics as possible and study them over a period of five years. A study of this size and duration should enable us to know with confidence whether or not the time you take your medication is important. Patients are invited through GP surgeries, hospitals and social media from all across the UK to participate.

£1 million is the value of the BHF grant for Professor Tom MacDonald’s research

Patients who currently take blood pressure medication twice daily (morning and evening), those who do night-shift work or those in other clinical trials at present can’t take part in this study.

Participants also need to have regular access to the internet, as this study is done by email and also through a link to a secure website. Although this excludes a certain proportion of patients, for practical and financial reasons it would be difficult to do a study of this size in the conventional way, where participants are seen by a clinician regularly. Previous studies that have used the web-based method found that correspondence was high-quality and cost-effective.

Can Heart Matters readers take part?

If they have an email account and are interested in being part of this study, they can visit or call 0800 917 3509 for detailed information that they should know before deciding whether to sign up. After registering an interest, they’ll be sent an email to confirm their desire to participate. We will then request explicit consent for us to access and use the information we need. This includes relevant medical records from GP surgeries and hospitals. We also ask for permission to write to the GP or a nominated next of kin in case we can’t get hold of participants.

Will the participants’ records be safe?

Even getting a modest effect within our study could imply an incredible benefit to the population at large

We are using a website that has been set up for this study and the data is stored as securely as possible. We have to indicate that we have secure data protection measures before this study is approved. We employ computer experts (known as ethical hackers) who deliberately attack our computer security system to test for any flaws we might have overlooked. Personal data will be treated with the strictest confidentiality by the staff working on the study, and publications of the results of the study will not include any identifiable details about participants.

Can a participant withdraw from the study at any time?

Yes. Equally, if during the research there was an enormous outcome difference between the groups, we may be instructed to discontinue the study, as it would be unethical to carry on.

How could this research help patients?

If this study showed that the time of day you take your blood pressure medication can have an effect on events such as strokes and heart attacks, it would provide enormous health benefits. Even getting a modest effect within our study could imply an incredible benefit to the population at large. We’d like to thank the BHF, which has funded this study, and the British Hypertension Society, which is co-ordinating it.

Professor MacDonaldProfessor Tom MacDonald

Professor MacDonald is a Professor of Clinical Pharmacology and Pharmacoepidemiology at Dundee University, as well as a Consultant Physician at Ninewells Hospital and Medical School. Professor MacDonald is also President of the British Hypertension Society.

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