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Angiotensinogen
Angiotensin I
Angiotensin II
Angiotensin III
Renin
ACE
Aminopeptidase
Non-ACE(eg. Chymase
in heart)
Endopeptidase
Angiotensin 1-7Releases ADH; ↑ PG;Natriuretic; ↓ RVR; ↓ BP (brain stem inj.)? Role in effects of ACEI
1 2 3 7 8 9 10
NH2-Asp-Arg-Val…Pro-Phe-COOH1 2 3 7 8 9 10
NH2-Asp-Arg-Val…Pro-Phe-COOH1 2 3 7 8
NH2-Arg-Val…Pro-Phe-COOH 2 3 7 8
NH2-Asp-Arg-Val…Pro-Phe-Hist-Leu…COOH
+
1. ↓ Renal PerfusionPressure2. ↓ Na at Macula Densa cells3. ↑ Sympathetic nerve activity (ß-1)
±PG
The Renin-Angiotensin System
Angiotensin II
Vasoconstriction
AldosteroneSecretion
Direct RenalSodium Retention
↑ Thirst
ADH Release
↑ Cardiac Contractility
Sympathetic Facilitation:CentralNerve terminal(ganglionic ?)
Cardiac & Vascular Hypertrophy
All known physiologic effects are mediated by the angiotensin II type 1 receptor
ANGIOTENSIN II - SUPPORT OF THE BLOOD PRESSURE
Angiotensin Converting Enzyme Inhibitors
Large number of drugs available differ mainly in the following:
1. Potency2. Route of elimination3. Duration of action4. Being prodrugs or active drugs Similar therapeutic indications, adverse
effects and contraindications
Adverse Effects
• Hypotension• Renal Insufficiency (if bilateral renal artery
stenosis)• Hyperkalemia – special group of patients (Na
restricted, on K-sparing diuretic, COX inhibitors)• Cough (20 %)• Angioedema• With captopril especially: neutropenia, nephrotic
syndrome, skin rash, taste disturbances (SH group- related).
Kinin-related (?)
Survival and Ventricular Enlargement Trial (SAVE)Asymptomatic Patients with EF<40% ACE Inhibitors in Severe Heart Failure
Patients with Severe Heart FailureCooperative New Scandinavian Enalapril Survival Study (CONSENSUS)
Captopril
Placebo
Mor
tali
ty R
ate
Pro
bab
ilit
y of
Su
dd
en D
eath
Pro
bab
ilit
y of
Su
rviv
al
Captopril
Hydralazine
Enalapril
Placebo
ACE Inhibitors – Effect onProgression of Diabetic
Nephropathy
Enalapril
Enalapril
Metoprolol
Metoprolol
Therapeutic Uses
• Anti-hypertensive• Prevent or reverse LVH• Protect against sudden death and second
myocardial infarction after acute MI• Improve survival and hemodynamics in
patients with congestive heart failure• Protect against progression of diabetic and
non-diabetic nephropathy
Angiotensin Receptor Blockers e.g. Losartan
• Block only the AT-1 subtype• Comparable effects to ACE Inhibitors in almost
all situations.• Less decrease in GFR in volume depleted states• Less side effects especially cough, angioedema,
rash• Block all AII effects and not dependent on
particular pathway
Kinins(?)
P E LP LC
P: PlaceboE: EnalaprilL: LosartanC: Captopril
3 m
onth
mor
tali
ty (
%)
SOLVD US +Int’lExercise
ELITE
(n=2569) (n=722)(n=736)
Fig. 3: 3-month mortality in three different studies
ELITE STUDY GROUP (Evaluation of Losartan in the Elderly) – Losartan better than captopril in patients with heart failure (chance finding?)
Captopril
Losartan
ELITE STUDY GROUP Losartan Superior to Captopril (? Chance Finding)
Pro
bab
ility
of
Su
rviv
al
Follow-up (days)
ELITE II STUDY GROUP (3,152 patients for 1.5 y)No Difference between Captopril and Losartan
ProbabilityOf Survival %
Event-freeProbability %
Lancet. 2000;355:1582-7.