Antihypertensive drugs - Dawes Flashcards
Hypertension and normal values are defined as?
H > 140/90
Optimal < 120/80
Major risk for?
Stroke
coronary artery disease
renal disease
retinal disease??
CVS death doubles for each
20mmHg systolic rise
10mmHg diastolic rise
epidemiology, risk factors?
increasing risk with age and many are poorly diagnosed and treated as it is often asymptomatic
Lifestyle changes that can aid prognosis?
Diet, especially sodium <100 mol/day
Weight loss
Exercise
Reduce alcohol
Problems with treatment
Lifelong disease - so if starting treatment at 40, will have to take meds for the next 40 years if gonna live to 80.
Concurrent diseases
Perceived benefits of treatment
Asymptomatic
Hypertension targets with different comorbidites
For hypertension <140/85
For diabetes/ end organ damage < 130/80
Proteinuria <125/75
Need to aim for even lover BP targets for the latter two because at an even higher risk of having an adverse cardiovascular event
ACE inhibitors / AII antagonists
e.g. cilazapril (ACE) or candesartan (AII) Often use ACE inhibitors preferably to AII's because they've been around longer and theres slightly more data but in people who cant tolerate give AII antagonists.
Contraindications of ACEi/ AII’s
Bilateral renovascular disease - AII maintains perfusion gradient - ACEi / AIIA --> marked hypotension - Deterioration renal function Pregnancy - cross placenta - angiotensin role in renal development
Suggest theories of how beta blockers reduce BP
Reduce CO Reset baroreceptors Renin inhibitor Central actions (reduce sympathetic activity) Presynaptic actions
Beta blocker side effects
wheeze / asthma exacerbation fatigue bradycardia negatively inotropic erectile dysfunction cold peripheries
Calcium channel blockers, which types do you use and why?
Dihydropyridine - Nifedipine - Felodipine - amlodipine Use pure vasodilators for hypertension They don't have much of an effect on the myocardium conducting tissue
Thiazide diuretics
e.g. benzofluarzide
Cheap and effective
amongst first line therapy
2 MOA’s
- Diuretics inhibit a channel in the DCT
Cause naturiesis –> pee out salt and water follows, patients don’t tend to notice diuretic effect
* also have a peripheral effect on VSM cells, open potassium channels so the cells become hyper polarised and less responsive to vasoconstriction
How do thiazide’s change BP with component factors?
Lose plasma vol and therefore CO drops, but after a week or two plasma vol and CO return to baseline even though BP remains stable.
Because the RAA gets activated when when BP drops. This RAA activation can often slightly offset the BP lowering effect therefore common combination therapy is giving thiazide with ACE inhibitor = synergy. Drug companies often produce combined pills
Loop diuretics
e.g. frusemide
Act in the ascending loop, inhibit Na+/K+/Cl- co transporter, powerful diuretic casing marked diuresis, useful in treatment of heart failure patients who’re fluid overloaded.
Doesn’t have as much of a vasodilator property as the thiazides, on its own does little in the way of decreasing BP unless combined with ace inhibitor.
Generally don’t use them as antihypertensives because a lot of other drugs available and because they’re potent diuretics, so don’t want patient to be peeing all the time.
Potassium sparing diuretics
spironolactone (aldosterone antagonist)
Aldosterone in collecting duct helps body hang onto sodium and makes you pee out K+ by blocking the aldosterone receptor in the CD. Spironolactone makes you pee out Na+ and water. need to keep and eye on K+ levels
Gynacomastia
hyperkalemia
Dehydration
Indication for spironolactone use
used in people with hypertension resistive to conventional therapy
Alpha blockers
vasodilators e.g. Doxazosin
Vasodilator
reduce prostatic symptoms
Minoxidil
very profound vasodilator, can cause huge sympathetic drive with activation RAAS, can get oedematous, is using have to combine with frusemide to offset oedema and ACE inhibitor and beta blocker can be complicated. Side effect making hair follicles grow
methyldopa
decrease sympathetic drive centrally, can be used during pregnancy very safe for babe
When do you decide to treat a hypertensive patients
>160/100 indication for pharmcogical therapy But >140/90 if - target organ damage - cerebrovascular disease - coronary artery disease - LVH - Heart failure - DM - protinurea / renal impairment - or if 10 year CVS risk >20%
For elderly could target at 150/90
140/85 DM
130/80 CKD
The British hypertension society recommendations
Younger, <55, and Non- Black –> A –> A + C or D
Older, > 55year or black –> C or D –> C or D + A
3rd stage = A + C + D
Step 4 = alpha blocker or spironolactone or other diuretic
Sensible drug prescription
1) ACEi
2) beta blockers
3) diuretics
4) alpha blockers
1) hypertension + heart failure
2) hypertension + angina / heart failure
3) hypertension + heart failure
4) Hypertension + potassium
Drugs you can use to treat pregnant women
central agents: metyl dopa
beta blockers: metoprolol, labetalol
Ca antagonists: Nifedipine
Vasodilators: Hydralazine
Essential hypertension
From early studies though that when really old (80+) wont get much benefit from lowering blood pressure, this has been disproved be recent study therefore treat everyone no matter the age.
Poly pills
in one tablet you could have lots of small doses of all the drugs we’ve been talking about, that could lower BP through a synergistic effect, but because they’re all super low doses don’t get any side effects.
