What are ACE Inhibitors?

Introduction 

What are ACE inhibitors? How do they work? What side effects do they cause. These are just some of the questions we answer in today’s blog. ACE inhibitors are, after all, among the most widely prescribed cardiovascular medicines.  

As pharmacy technicians, you will invariably come across many ACE inhibitors. 

They are important medicines – and are easily identified as they all contain the suffix –pril.  

Drug	Brand Name
Ramipril	Altace
Lisinopril	Prinivil Qbrelis Zestril
Captopril	Capoten
Enalapril	Epaned Vasotec
Perindopril	Aceon

The indications of a medicine refer to what it is used to treat. 

There are four primary indications of ACE inhibitors, including: 

• Hypertension – reducing blood pressure and the risk of stroke and/or heart attacks. 
• Chronic heart failure – to improve symptoms and prognosis. 
• Ischemic heart disease – reduce further heart attack or stroke risks. 
• Diabetic nephropathy – reduce proteinuria and worsening of the disease. 

As part of the pharmacy technician exam, students can expect some questions on ACE inhibitors. Due to their widespread use in medicine, questions often relate to either brand names, to identifying an ACE inhibitor from a list of medicines, or by asking students to identify what an ACE inhibitor is used to treat.  

Now we know what ACE inhibitors are used to treat, next we need to learn more about their pharmacology – their mechanism of action. 

Mechanism of Action 

As their name suggests, ACE inhibitors inhibit ACE – the angiotensin-converting enzyme.  

The ACE enzyme plays an important role in increasing blood pressure. Normally, the enzyme converts angiotensin I into angiotensin II. Angiotensin II has two broad effects: 

• Vasoconstriction – increasing blood pressure. 
• Promoting release of aldosterone – a hormone that plays a significant role in increasing blood pressure by promoting the body to retain water and sodium.  

By blocking the ACE enzyme, ACE inhibitors prevent these two hypertensive mechanisms and therefore work to reduce blood pressure. By preventing the release of aldosterone, water and sodium are not encouraged to remain in the body – again, having a hypotensive effect. 

Side Effects 

One of the most prominent side effects of ACE inhibitors is their propensity to cause a persistent, dry cough.  

This can often prove troublesome for the patient. Clinicians may decide to change to another hypotensive drug – such as angiotensin-receptor blockers (examples of which include candesartan and losartan).  

Other side effects of ACE inhibitors include: 

• Elevated potassium levels (hyperkalemia) 
• Increased risk of renal failure  
• Hypotension – which is worst after the first dose 

“First-dose hypotension” is a significant risk and so patients are often counselled to take the first dose before bed.  

ACE inhibitors increase potassium levels in the body (low aldosterone levels cause potassium retention) which, in turn, increases the risk of arrhythmias. For this reason, they should not be taken with potassium supplements or other drugs – such as potassium-sparing diuretics – which serve to increase potassium levels further.  

ACE inhibitors are not safe in pregnancy and so should be avoided. There are other safe medicines that can be used to treat gestational hypertension – including: 

• Nifedipine 
• Labetalol 
• Hydralazine 
• Methyldopa 

Sample PTCB Practice Questions 

To prepare for the PTCB exam, students are advised to practice as many PTCB questions as possible. This helps to identify your strengths and weaknesses, where you need to study more, and how to plug gaps in knowledge.  

Here is a small sample of PTCB practice questions that reflect the style and standard of questions you can expect to face on the day of your exam: 

Q. What is the active ingredient of the medicine, Altace? 

a. Labetalol 

b. Ramipril 

c. Metformin 

d. Prednisolone 

Q. ACE inhibitors can be identified as they all contain which suffix? 

a. -lol 

b. -pril 

c. -sone 

d. -ate 

Q. Which of these side effects is most associated with ACE inhibitors? 

a. Low potassium levels 

b. Hypertension 

c. Elevated glucose levels 

d. Persistent, dry cough 

Q. ACE inhibitors are used to treat conditions that affect which body system? 

a. Immune system 

b. Musculoskeletal system 

c. Cardiovascular system 

d. Central nervous system 

Conclusion 

ACE inhibitors are an important medicinal class in the treatment of a wide range of cardiovascular disease. 

As pharmacy technicians, you will handle this important drug class daily – working within the community or hospital pharmacy and patients to deliver these essential medicines to patients. 

It is important that you have a rounded knowledge of this drug class. Here, we have spelled out the complete range of clinical and pharmacological details you should know. On the PTCB test, you should expect at least 1-2 questions on ACE inhibitors.  

If you are already a member of PTCB Test Prep, you already have access to exam-like questions and detailed, explanatory answers. If you are not yet registered, take a few moments to register now.  

Check back to our PTCB blog soon for more great content to help you master the science of medicines and dominate your next pharmacy exam.