Generality
ACE inhibitors (also known as Angiotensin Converting Enzyme inhibitors) are drugs used mostly in the treatment of hypertension.
Under physiological conditions, renin release is stimulated by renal sympathetic activity, by the reduction of pressure in the preglomerular vessels and by the reduction of the concentration of sodium ions in the blood.
Once released, renin allows the transformation of angiotensinogen into angiotensin I, which is then converted by the ACE (Angiotensin Converting Enzyme) into the active form angiotensin II. The latter is a vasoactive substance which - interacting with the AT1 receptors - causes vasal proliferation (hypertrophy), vasoconstriction, synthesis and release of aldosterone, with consequent saline retention and stimulation of the sympathetic system (a system that is activated for long-term control If the sympathetic system did not function properly, hypertension problems would arise, therefore in such circumstances it is necessary to block the ACE enzyme and prevent the transformation of angiotensin I into angiotensin II.
The active ingredients such as captopril (Capoten®), lisinopril (Zestril®, Zestoretic®), enalapril (Converten®, Enapren®, Vasoretic®), fosinorpil (Eliten®) belong to the class of ACE inhibitors. ramipril (Triatec®, Triatec HCT®), perindopril (Reaptan®, Coversyl®), benazepril (Cibacen®) and quinapril (Acequin®).
Therapeutic indications
As mentioned, ACE inhibitors are mainly indicated in the treatment of hypertension, but are also used in the treatment of congestive heart failure and myocardial infarction.
ACE inhibitors can be used either alone or in combination with other drugs with hypotensive action, such as, for example, diuretics and calcium channel blockers.
Mechanism of action
ACE inhibitors, as you can easily guess, are active ingredients capable of inhibiting the activity of the angiotensin converting enzyme, preventing the transformation of angiotensin I into angiotensin II and thus exerting an antihypertensive action.
However, the ACE enzyme does not just convert angiotensin I into angiotensin II, but also plays an important degrading action against bradykinin, a polypeptide that stimulates the production of prostaglandins and exerts a powerful vasodilator effect, complementary to the "antihypertensive effect.
Therefore, ACE inhibitors are also capable of inducing an enhancement of the activity of bradykinin which, in turn, is capable of exerting a hypotensive effect. However, it should be noted that the enhancement of the action of bradykinin is a "weapon to double cut, since, if on the one hand it contributes to the hypotensive effect deriving from the blocking of the conversion of angiotensin I into angiotensin II, on the other hand it can give rise to some side effects (see paragraph "Side Effects").
Finally, it should be remembered that - with the exception of captopril which is the progenitor of ACE inhibitors and whose duration of action is rather short - all the other ACE inhibitors are formulated as prodrugs which, before being able to carry out their activity, they must be properly converted into their active form by adequate liver enzymes.
Interactions with other drugs
ACE inhibitors can establish a series of drug interactions with various active ingredients. These include:
- Allopurinol;
- Antacids, as these drugs can reduce the bioavailability of ACE inhibitors in case of simultaneous use;
- Digoxin and lithium, as ACE inhibitors can increase their plasma concentrations;
- NSAIDs, as these drugs may reduce the hypotensive efficacy of ACE inhibitors;
- Phenothiazines, as they can potentiate the effect of ACE inhibitors;
- Preparations containing potassium and potassium-sparing diuretics, since there is an increased risk of "onset of" hyperkalaemia following concomitant therapy with ACE inhibitors;
- Capsaicin, as it can cause worsening of cough caused by ACE inhibitors.
Side effects
The type of adverse effects and the intensity with which they occur depend both on the active principle that one intends to use, and on the sensitivity of each patient towards the chosen drug.
However, there are some undesirable effects that are common to the entire class of ACE inhibitors, among them we remember:
- Allergic reactions, even severe ones, which can manifest themselves in the form of angioedema and skin rash;
- Hypotension;
- Hyperkalemia;
- Changes in the sense of taste
- Rashes;
- Headache;
- Dizziness;
- Nausea, vomiting and diarrhea;
- Fatigue;
- Neutropenia;
- Proteinuria;
- Acute renal failure.
Finally, ACE inhibitors can also cause the onset of dry cough. This type of undesirable effect is not considered of primary importance during therapy with these drugs. However, it seems to be due precisely to the enhancement of bradykinin activity - therefore the increased synthesis of prostaglandins - induced by ACE inhibitors.
Contraindications
The use of ACE inhibitors is contraindicated in patients with known hypersensitivity to any of these active substances.
Also, due to the harm they can cause to the fetus, ACE inhibitors should not be taken by pregnant women, especially during the second and third trimester of gestation.
The use of ACE inhibitors is also contraindicated in mothers who are breastfeeding.
Other articles on "ACE inhibitor drugs"
- Beta-Blocker Drugs
- AT1-antagonist or sartan drugs
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