Scheme of Renin-angitensin-aldosterone system
ACE inhibitor drug list
- Captopril
- Enalapril
- Lisinopril
- Fosinopril
- Ramipril
- Quinapril
- Benzpril
- Moexipril
- Perindopril
Mechanism of action of ACE inhibitors
ACE inhibitors acts by blocking ther action of angiotensin converting enzyme (ACE), which cleaves angiotensin I to potent vasoconstrictor angiotensin II, by reducing circulating angiotensin II levels, ACE inhibitors decrease aldosterone secretion from adrenal medulla, also these drugs reduce the rate of bradykinin inactivation.
Pharmacological actions of ACE inhibitors on the heart
ACE inhibitors reduce cardiac workload by reduction of
preload (venous return), afterload (peripheral vascular resistance) and blood
pressure by reducing plasma volume by blunting angiotensin II mediated
aldosterone secretion.
Indication of ACE inhibitors
ACE inhibitors have a considerable value in the treatment of
such diseases as heart failure (ACE inhibitors has significantly reduce mortality
and morbidity associated with heart failure),
hypertension (these drugs are considered first line
treatment in hypertension) , nephropathy associated with diabetes mellitus (due
to nephroprotective properties of ACE inhibitors) , proteinuria in patients
with CKD is also an indication for the use of ACE inhibitors(proven effects on
reducing proteinuria), ischemic stroke, stable angina and patients who had
suffered of myocardial infarction.
Pharmacokinetics of ACE inhibitors
All ACE inhibitors are incompletely absorbed following oral
administration.The presence of food reduce absorption (should be taken on an
empty stomach).
Except for captopril, all other ACE inhibitors are prodrugs require
activation by hydrolysis via hepatic enzyme.
Renal elimination of the active moiety is important for most
ACE inhibitors with exception of fosinopril (heptic excretion).
Adverse effects of ACE inhibitors
The most common adverse effect of ACE inhibitors is the dry
cough (may lead to incompliance of the patients and replacing ACE inhibitors by
ARBs), adverse effects also include skin rash, postural hypotension , bitter taste,
angioedema, hyperkalemia and renal insufficiency.
Nephroprotective actions of ACE inhibitors
ACE inhibitors have shown nephroprotective properties on the
long term, which is related to angiotensin reducing effects on the renal
arteries.
ACE inhibitors cause vasodilatation of efferent renal
artery, resulting in decreased intraglomerular pressure.
On the short term ACE inhibitors may decrease renal function
because of reduced glomerular filtration as a result of reduced glomerular
pressure, but on the long term ACE inhibitors protect the kidney because
increased glomerular pressure for long period leads to renal damage and kidney
injury with time.
When to stop ACE inhibitors?
If the glomerular filtration rate (GFR) has reduced by 70%
of the baseline measurement stop ACE inhibitors.
Drug interactions of ACE inhibitors
Most common drug interactions of ACE inhibitors include NSAIDs and potassium supplements.
·
NSAIDs: both ACE inhibitors
and NSAIDs cause potassium retention in the body so both drugs should not be
used together because of increased risk of hyperkalemia.
·
Potassium supplements and salts: because ACE
inhibitors can rise potassium blood levels, so avoid the use of potassium
supplements or potassium salts in conjunction with ACE inhibitors.
Concomitant use of ACE inhibitors and potassium sparing diuretics
The concomitant use of these drugs could be indicated for
some patients such as patients with resistant hypertension and patients with
proteinuria (spironolactone reduce proteinuria when combined with ACE
inhibitors), but when these drugs combined with each other close monitoring of
potassium levels should be done to avoid occurrence of serious hyperkalemia.
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