2. OUTLINE
• Intro; MI- Management
• ACEIs- class definition
• Examples
• MOA
• Rationale for the use of ACEIs in MI
• RAAS
• SAR of ACEIs
• Pharmacology of a prototypical ACEI; CAPTOPRIL
• Pharmacology of Lisinopril
• Drug interractions
• Counselling points
• Side effects
• Discussion
• Conclusion
2
3. INTRO
• Myocardial infarction is myocardial necrosis caused by acute
occlusion of a coronary artery due to plaque rupture or erosion with
superimposed thrombosis.
• Approximately 1 million Americans will have a new or recurrent
myocardial infarction this year (National registry of myocardial
infarction). Nigeria?
• Coronary heart disease is the single largest cause of death in the
United States.
• The estimated direct and indirect costs of coronary heart disease to
GDP= $95.6 billion/year (National Registry of Myocardial infarction)
• Management involves non-drug measures and drug therapy,
including, thrombolytics, β- blockers, statins, ARBs, Antiplatelet
therapy, aldosterone receptor antagonism, ACE inhibitors.
3
4. DEFINITION OF CLASS
• ACEIs are drugs that competitively inhibit angiotensin converting
enzyme (ACE).
• Thus inhibiting the production of angiotensin II.
• ↓ TPR, hence BP
• ↓ aldosterone
• ↓ Na retetion
• ↓ H2O retention
4
5. EXAMPLES
• Captopril
• Enalapril
• Lisinopril
• Fosinopril
• Quinapril
• Trandolapril
• Benazepril
CLASSIFICATION OF ACEIs
(Based on Zn+2 binding moeity)
• Sulfhydryl-containing agents: Captopril (Active drug),
the first ACE inhibitor, Zofenopril,
Alacepril and Moveltipril.
• Dicarboxylate-containing agents: This is the largest
group, including: Enalapril, Ramipril,
Quinapril, Perindopril, Lisinopril (Active drug),
Benazepril, Cilazapril, Delapril and
Spirapril
• Phosphonate-containing agents: Fosinopril and SQ
29852
• Naturally occuring ACEIs; Casokinins and lactokinins,
breakdown products of casein and whey, occur
naturally after ingestion of milk products, especially
cultured milk. Their role in blood pressure control is
uncertain (Fitzgerald et al, 2004). 5
6. MOA
• Binding to ACE
• Inhibition of angiotensin II synthesis leading to decreased blood
pressure + cardiovascular protection from hemodynamically
mediated effects of angiotensis II on cardiac cells.
• cardiopretective action from angiotensinII effects on the heart.
6
8. RAAS
• The renin-angiotensin-aldosterone system (RAAS) is a signaling pathway
responsible for regulating the body's blood pressure.
• Stimulated by low blood pressure or certain nerve impulses (e.g. in stressful
situations), the kidneys release an enzyme called renin. This triggers a
signal transduction pathway: renin splits the protein angiotensinogen,
producing angiotensin I. This is converted by another enzyme, the
angiotensin-converting enzyme (ACE), into angiotensin II.
• Angiotensin II not only causes blood vessels to narrow (vasoconstriction), it
also simultaneously stimulates the secretion of the water-retaining hormone
vasopressin (also called AVP) in the pituitary gland (hypophysis) as well as
the release of adrenaline, noradrenaline and aldosterone in the adrenal
gland.
8
9. RATIONALE FOR THE USE OF
ACEIs IN MI
• This underlines the role of the Renin-Angiotensin-Aldosterone
System (RAAS) in the pathological changes that occur post MI.
• RAAS contributes to the eccentric cardiac hypertrophy and fibrosis
seen in MI by stimulating the migration (Bell and Madri, 1990;
Dubey et al., 1995), proliferation (Daemen et al., 1991),
hypertrophy and increased ECF production by cardiac fibroblasts
(Villarreal et al., 1993; Crawford et al., 1994; Ostrom et al., 2003).
• RAAS also contributes to the hypertophy (Itoh et al., 1993), and
increased production of ECF by vascular smooth muscle cells
(Scott-Burden et al., 1990).
9
10. Rationale contd
• Angiotensin II acts directly on cells to induce the expression of
specific proto-oncogenes
• Angiotensin II rapidly (within minutes) increases steady-state levels
of mRNAs which alters the expression of several genes that
stimulate cell growth (hypertrophy and hyperplasia), including basic
fibroblast growth factor, platelet-derived growth factor, and
transforming growth factor ᵝ
• changes in cardiac preload (volume expansion owing to Na+
retention) and afterload (increased arterial blood pressure) probably
contribute to cardiac hypertrophy and remodeling(goodman and
gilman, 2006).
10
11. Rationale contd
• Arterial hypertension also contributes to hypertrophy and
remodeling of blood vessels.
11
13. SAR Contd
• The N-ring must contain a carboxylic acid to mimic the C-terminal
carboxylate of ACE substrates.
• Large hydrophobic heterocyclic rings (i.e., the N-ring) increase
potency and alter pharmacokinetic parameters.
• The zinc binding groups can be either sulfhydryl (A), a carboxylic
acid (B), or a phosphinic acid (C).
• The sulfhydryl group shows superior binding to zinc (the side chain
mimicking Phe in carboxylate and phosphinic acid compounds
compensates for the lack of a sulfhydryl group)
13
14. SAR Contd
• Sulfhydryl-containing compounds produce high incidence of skin
rash and taste disturbances.
• Sulfhydryl-containing compounds can form dimers and disulfides
which may shorten duration of action.
• Compounds which bind to zinc through either a carboxylate or
phosphinate mimic the peptide hydrolysis transition state.
• Esterification of the carboxylate or phosphinate produces an orally
bioavailable prodrug.
14
15. SAR Contd
• X is usually methyl to mimic the side chain of alanine. Within the
dicarboxylate series, when X equals n-butylamine (lysine side chain)
this produces a compound which does not require prodrug for oral
activity.
• Optimum activity occurs when stereochemistry of inhibitor is
consistent with L-amino acid stereochemistry present in normal
substrates
15
18. CAPTOPRIL (CAPOTEN)
• Captopril was the first inhibitor for clinical trial.
• Reported to have a more favorable effect on QOL (Testa et al, 1993)
• According to the mechanism proposed by Ondetti and colleagues,
captopril interacts with the enzyme through several bonds, i.e.
electrostatic, hydrogenic and lipophilic connections.
• Among these, a co-ordinance bond formed between the free thiol
group of captopril and zinc ion in the active site of ACE.
18
20. Captopril contd
• Captopril, the first ACE inhibitor to be marketed, is a potent ACE
inhibitor.
• It is the only ACE inhibitor approved for use in the United States
that contains a sulfhydryl moiety.
• Given orally, captopril is absorbed rapidly and has a bioavailability of
about 75%.
• Peak concentrations in plasma occur within an hour, and the drug is
cleared rapidly with a half-life of approximately 2 hours
20
21. Captopril contd
• Most of the drug is eliminated in urine, 40% to 50% as captopril and
the rest as captopril disulfide dimers and captopril-cysteine disulfide.
• The oral dose of captopril ranges from 6.25 to 150 mg two to three
times daily, with 6.25 mg three times daily or 25 mg twice daily being
appropriate for the initiation of therapy.
• Most patients should not receive daily doses in excess of 150 mg.
Since food reduces the oral bioavailability of captopril by 25% to
30%, the drug should be given 1 hour before meals
21
22. Lisinopril (PRINIVIL,
ZESTRIL).
• Lisinopril, the third ACE inhibitor approved for use in the United
States, is the lysine analogue of enalaprilat; unlike enalapril,
lisinopril itself is active (Goodman ad Gilman, 2004).
• In vitro, lisinopril is a slightly more potent ACE inhibitor than is
enalaprilat. Lisinopril is absorbed slowly, variably, and incompletely
(about 30%) after oral administration (not reduced by food); peak
concentrations in plasma are achieved in about 7 hours.
• It is cleared as the intact compound by the kidney, and its half-life in
plasma is about 12 hours.
23. Lisinopril contd
• Lisinopril does not accumulate in tissues.
• The oral dosage of lisinopril ranges from 5 to 40 mg daily (single or
divided dosage), with 5 and 10 mg daily being appropriate for the
initiation of therapy.
• A daily dose of 2.5 mg is recommended for patients with heart failure
who are hyponatremic or have renal impairment
23
26. Counselling points for ACEIs
• Might feel dizzy when you start taking this medicine. Get up
gradually from sitting or lying position to minimize this effect. Sit or
lie down if patient becomes light headed or dizzy.
• Do not take potassium supplements or consume too much banana
while taking this medication unless your doctor instructs otherwise.
• When starting ACEIs, stop potassium-sparing diuretics, for 24 hours.
• Always start with low doses.
• Check renal function and electrolytes before starting ACEIs and
review after 1-2 weeks.
• Report promptly when untoward effects occur.
26
27. Common side effects of ACEIs
• Angioedema
• Fetotoxicity
• Skin rashes (esp. Captopril due to sulfhydryl group)
• Acute renal failure
• Dry cough
• Headache
• Nausea
• Dizziness
• Fatigue
27
28. DISCUSSION
• ACEIs increase survival when administered early after an acute
myocardial infarction (MI) (Khalil et al).
• The early benefit of ACE inhibitor therapy
suggests that starting ACE inhibitors within 24 h has an
effect on the infarcted myocardium either by limiting infarct
size or by reducing infarct expansion (GISSI Trial, 1994)
28
30. DISCUSSION contd
• Since activation of the renin-angiotensin
system has been shown to be an independent predictor of
ischemic event (Alderman et al, 1991), ACEIs help prevent MI.
• Additionally, ACE inhibition has been shown to counteract
several atherosclerotic processes including thrombosis, lowdensity
lipoprotein oxidation, proliferation of vascular
smooth muscle cells and local accumulation of neutrophils
contributing to MI (Mancini, 1996).
• Preliminary data have shown that ACE
inhibition improves endogenous fibrinolytic function (Moriyama et al
1997).
30
31. CONCLUSION
• ACEIs have proven to be aces in the hole for virtually all cardiac
patients as the RAAS appears to be a constant meddler in majority
of cardiovascular events, which contribute a high percentage to
morbidity and mortality worlwide.
• They have a proven efficacy in the management of MI especially
when started early in the post-infarction period.
• A meta-analysis of all published, major trials investigating the use of
an ACEI after an MI conclusively supports a role for ACEI therapy in
the early phase and ongoing management of MI (Latini et al, 1995).
31
32. REFERENCES
• FitzGerald RJ, Murray BA, Walsh DJ; Murray, BA; Walsh, DJ (2004).
"Hypotensive peptides from milk proteins". The Journal of nutrition
134 (4): 980S–8S. PMID 15051858
• Goodman & Gilman's The Pharmacological Basis Of Therapeutics -
11th Ed. (2006)
• Bell, L., and Madri, J.A. Influence of the angiotensin system on
endothelial and smooth muscle cell migration. Am. J.
Pathol., 1990, 137:7-12. PUBMED
• Daemen, M.J.M.P., Lombardi, D.M., Bosman, F.T., and Schwartz,
S.M. Angiotensin II induces smooth muscle cell proliferation in the
normal and injured rat arterial wall. Circ. Res., 1991, 68:450-456.
PUBMED
•
32
33. REFERENCES
• Villarreal, F.J., Kim, N.N., Ungab, G.D., Printz, M.P., and Dillmann,
W.H. Identification of functional angiotensin II receptors on rat
cardiac fibroblasts. Circulation, 1993, 88:2849-286l. PUBMED
• Crawford, D.C., Chobanian, A.V., and Brecher, P. Angiotensin II
induces fibronectin expression associated with cardiac fibrosis in the
rat. Circ. Res., 1994, 74:727-739. PUBMED
• Ostrom, R.S., Naugle, J.E., Hase, M., et al. Angiotensin II enhances
adenylyl cyclase signaling via Ca++/calmodulin: Gq-Gs cross-talk
regulates collagen production in cardiac fibroblasts. J. Biol. Chem.,
2003, 278:24461-24468. PUBMED
• Testa, M.A., Anderson, R.B., Nackley, J.F., Hollenberg, N.K., and the
Quality-of-Life Hypertension Study Group. Quality of life and
antihypertensive therapy in men: A comparison of captopril with
enalapril. New Engl. J. Med., 1993, 328:907-913. PUBMED
33
34. REFERENCES
• Itoh, H., Mukoyama, M., Pratt, R.E., Gibbons, G.H., and Dzau, V.J.
Multiple autocrine growth factors modulate vascular smooth muscle
cell growth response to angiotensin II. J. Clin.
Invest., 1993, 91:2268-2274. PUBMED
• Scott-Burden, T., Hahn, A.W.A., Resink, T.J., and Buhler, F.R.
Modulation of extracellular matrix by angiotensin II: Stimulated
glycoconjugate synthesis and growth in vascular smooth muscle
cells. J. Cardiovasc. Pharmacol., 1990, 16(suppl. 4):S36-S41
• Rajeev Kumar, Ramji Sharma, Khamji Barwa, Ram kumar Roy, Aran
Kumar, Atul Baruwa. Moder developmet in ACE Ihibitors. Der
Pharmacia Lettre, 2010; 2(3):388-419
• Mohammed E. Khalil, Abul W. Basher, Edward J. Brown, JR,
Imad A. Alhaddad. A Remarkable Medical Story: Benefits of
Angiotensin-Converting Enzyme Inhibitors in Cardiac Patients.
Journal of the American College of Cardiology. 2001. 37(7): 34
35. REFERENCES
• Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto
Miocardico. GISSI-3: effects of lisinopril and transdermal glyceryl
trinitrate singly and together on six-week mortality and ventricular
function after acute MI. Lancet 1994;343:1115–22
• Ng, K.K.F. & Vane, J.R. Conversion of angiotensin I to angiotensin II.
Nature 216,
762–766 (1967)
35
36. CREDITS:
• Pharm. Khadijat S Adejumo
• Pharm. Nicholas A
• Pharm. Ibrahim James Oyibo
• Mr Isa Buba and Mr Nasiru
THANK YOU ALL FOR LISTENING.
QUESTIONS?
36
Notas do Editor
Effect of ACE-inhibitor therapy on cumulative mortality during days 0 to 30 in all trials combined.