ACE Inhibitors Flashcards
What drugs are ACE Inhibitors?
Ramipril
Lisinopril
Enalopril
Catopril
What is the mechanism of action for ACE Inhibitors?
inhibits action of angiotensin converting enzyme - a key enzyme involved in the renin-angiotensin aldoslerone system (RAAS)
How do ACE inhibitors inhibit the action of the angiotensin converting enzyme?
Renin release
kidneys release renin due to low BP, blood and salt levels. angiotensinogen, a liver produed protein is converted to angiotensinogen II by renin.
Conversion from I to II
angiotensin I - inactive precursor, needs to convert to angiotensin II to become active. conversion catalysed by angiotensin converting enzyme (found in lungs)
Angiotensin II effects: potent vasconstrictor, narrows blood vessels which increases BP.
stimulated release of aldesterone from adrenal glands - promotes sodium and water retainment by the kidneys - increases blood pressure and volume.
Angiotensin II can lead to hypertrophy of the heart muscles.
Benefits of ACEI
Vasodilation: relaxed blood vessels and dilated. lowers blood pressure by lowering resistance to blood flow.
Reduced aldesterone release:
angiotensin II stimulates aldesterone release. ACE lowers aldesterone leading to low sodium and water retention
reduced sodium and water retention:
low aldesterone means kidneys excrete more sodium and water, which lowers BP levels and BP volume.
Anti remodelling effects:
low angiotensin means low hypertrophy of heart muscles
What can ACEI be used for?
Hypertension
Heart Failure
Post MI
why is ACE used for heart failure?
reduces work load on heart by dilating blood vessels to increase blood flow to organs.
how does ace increase blood flow to organs for HF?
blocking conversion of angiotensin I to angiotensin II as this acts as a vasoconstrictor under certain circumstances.
ACE for hypertension
people under 55
note: not recommended for African/Caribbean as less tolerated.
patients over 55 where BP using primary strategy such as CCB and TLD can use ACE as second line treatment.
ACE for post MI
ACE on of core drugs for secondary prevention of MI.
if patient cant take ACE hen ARB is prescribes.
how is ACE titrated post MI?
usually increased at short intervals e.g. 12-24 hours before patient leaves hospital. if titration not completed at this time, then 4-6 weeks after discharged from hospital.
What are the cautions and contraindications of ACEI?
Aortic or Mitral valve stenosis - ARB and ACEI contraindicated. Masks begin in of ventricular damage in heart.
Patients with history of angioedema - ACEI and ARB can experience angioedema. If ACEI does ARB NOT to be given.
Elderly - lower dose to prevent dry cough or postural hypotension
Pregnancy - ARBS contraindicated
Significant interactions with ACEI
Lithium increase - lithium toxicity. Manufacturer advises to monitor lithium and adjust dose accordingly.
Diuretics - NICE: rapid fall in BP in a patient who is volume depleted
NSAIDS - hypotension effect, increased risk of renal impairment and AKI.
ARB - increased risk of hyperkalaemia, hypotension and renal impairment.
