ACE inhibitors and low-renin hypertension in Black African and African-Caribbean people
ACE inhibitors (drugs that turn down the renin-angiotensin hormone chain) lower blood pressure less well on average in Black African and African-Caribbean people, who more often have low-renin hypertension.
Remember
When a Black African or African-Caribbean adult without type 2 diabetes needs hypertension treatment started, NICE offers a calcium channel blocker, because ACE inhibitors lower blood pressure less well on average in this group, and low-renin hypertension is the proposed explanation. That is a group average, not a rule for each person.
Memory aid
If renin is already low, an ACE inhibitor is turning down a tap that is barely running.
Low renin means the chain is already running slowly, so an ACE inhibitor has little left to turn down.
Renin is an enzyme released by the kidney. It starts the renin-angiotensin-aldosterone system (RAAS), a hormone chain that narrows blood vessels and makes the body hold on to salt and water. ACE inhibitors (angiotensin-converting enzyme inhibitors, such as ramipril) lower blood pressure by blocking the second step of this chain.
On average, Black African and African-Caribbean people are more likely to have low-renin hypertension, in which the chain is less active. There is then less for an ACE inhibitor to block, so the average fall in blood pressure is smaller. The low-renin explanation is a proposed one: it describes a population-level difference in drug response (an average trend across a group), not a strict genetic rule.
In UK guidance, the step 1 drug (the one treatment starts with) for adults whose family origin is Black African or African-Caribbean, and who do not have type 2 diabetes, is a calcium channel blocker (a drug that relaxes and widens blood vessels), such as amlodipine, at any age. If a drug acting on the renin-angiotensin system is still needed, NICE advises considering an angiotensin II receptor blocker (ARB) in preference to an ACE inhibitor in this group. An ARB blocks the receptor that angiotensin II, the hormone that narrows blood vessels, acts on.
The rule describes averages, so family origin guides the first choice but each patient still needs individual review.
Key facts
- Group
- Black African and African-Caribbean adults respond less well to ACE inhibitors on average.
- Proposed reason
- low-renin hypertension is more common in Black African and African-Caribbean people, so the renin-angiotensin hormone chain is less active.
- UK guidance
- NICE offers a calcium channel blocker as the step 1 drug to adults with a Black African or African-Caribbean family origin and no type 2 diabetes, at any age.
- ACE inhibitor or ARB
- these are the step 1 choice for people with type 2 diabetes and for those under 55 who are not Black African or African-Caribbean.
- ARB nuance
- if a drug acting on the renin-angiotensin system is needed in Black African and African-Caribbean adults, NICE advises considering an ARB in preference to an ACE inhibitor.
- Limit
- a population average, not a rule for any one patient.
Exam traps
- When a drug acting on the renin-angiotensin system is chosen for a Black African or African-Caribbean adult, NICE advises considering an angiotensin II receptor blocker (ARB) in preference to an ACE inhibitor, but an ARB is still not the step 1 drug for such an adult without type 2 diabetes, because it acts on the same renin-angiotensin chain, which is relatively less active in low-renin hypertension.
- In a Black African or African-Caribbean adult without type 2 diabetes, a thiazide-like diuretic (such as indapamide, a drug that removes salt and water) is offered at step 1 only if a calcium channel blocker is not tolerated, for example because of ankle swelling (oedema), or if there is heart failure.
- An ACE inhibitor (or an ARB) is the step 1 choice for people with type 2 diabetes and for those under 55 who are not Black African or African-Caribbean, so neither is the first offer for a Black African or African-Caribbean adult without type 2 diabetes.
Read the full notes
Tested in 6 SimpleMed+ questions
Practice it in Pharmacology, with the answer and a full explanation after every question.
Practice these questions