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What Is the Difference between Enalapril and Captopril?

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  • Written By: S. Berger
  • Edited By: Shereen Skola
  • Last Modified Date: 01 November 2016
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Both enalapril and captopril are medications used in the treatment of high blood pressure caused by hypertension, heart failure, and other medical conditions. These drugs work in similar ways, and are both classified as angiotensin-converting enzyme (ACE) inhibitors due to their action of preventing the ACE protein from constricting the blood vessels of the body. There are some differences between these medications, despite their similarities, that can lead to doctors choosing to prescribe one over the other in certain situations.

One major difference between enalapril and captopril pertains to how they are administered to patients. Enalapril may be given to patients as a tablet to take orally, or it may be injected intravenously (IV) for immediate action. Captopril, on the other hand, is always given to the patient orally, meaning that it is not typically used to relieve emergency hypertensive crises.

The difference in the way that enalapril and captopril are administered has to do with their relative strengths. Dosages of captopril are higher, starting at 25 milligrams (mg), because it is considered a weaker drug. Additionally, it has a higher oral bioavailability than enalapril, meaning that it absorbs into the bloodstream more effectively when taken by mouth. Initial active doses for enalapril are 5 mg for oral use, and 1.25 mg when given in IV form, due to its more efficient means of blocking the ACE protein.

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Duration of action is another point of disparity between enalapril and captopril. Enalapril has a 19 hour half-life, or the time it takes for half of the drug to be broken down and removed from the body after ingestion. The half-life of captopril is only 1.9 hours, which is another reason it is not used in hypertensive emergencies. Shorter half-lives require additional dosing at more frequent intervals, which is undesirable during a serious medical situation.

The side effects of enalapril and captopril show some variation. ACE inhibitors, including both of these drugs, tend to cause dizziness, hypotension, and coughing. Additional side effects can be seen with captopril that are not present in other drugs of its class, however. It contains a sulfur atom in its structure that other ACE inhibitors do not have, leading to unique potential side effects including rashes, and a lingering metallic taste on the tongue that some patients experience. Postural hypotension, or a loss of blood pressure when rapidly standing up, is another side effect occurring only in captopril, and exists because of the drug's rapid onset speed.

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literally45
Post 3

I heard that some people use ACE inhibitors, especially captopril, to lose fat. I think this is very dangerous. It can lower blood pressure too much.

serenesurface
Post 2

I don't know about captopril, but enalapril is a great drug for emergency situations. I'm on beta-blockers for high blood pressure. I don't usually take enalapril. However, sometimes my blood pressure rises too much, especially when I have a fever. My regular medication isn't enough in these cases and I end up being hospitalized. At my last visit to the ER, the doctor prescribed me enalapril. She said to carry it with me and if my blood pressure goes above 140/90, I should take an enalapril to reduce it.

The other day I was sick and my blood pressure went up to 160/110. I took enalapril right away and in half an hour it went back down to 130/90. I still went to the hospital to make sure I would be okay, but it certainly felt like enalapril saved my life. In another hour, my blood pressure was down to normal range.

ysmina
Post 1

I was on captopril but I asked my doctor to switch me to another drug because it was making me cough. I developed a constant cough while on captopril. So my doctor switched me to enalapril. I was happy on it for the first several weeks and lo and behold, enalapril gave me a cough too. It's not as bad as it was on captopril, but I still get it.

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