PBL 6 Flashcards
What type of drug is Amlodipine? What is its basic effect on the body? What is it prescribed for? (2)
Amlodipine is a long-acting calcium channel blocker. It acts primarily on vascular smooth muscle and dilates the arteries, this lowers blood pressure and makes it easier for the heart to pump blood. As a result, the heart needs less oxygen. It is prescribed for the treatment of hypertension and chronic stable angina
What type of drug is bendroflumethazide, in basic terms? What do you prescribe it for? (3)
A thiazide diuretic. It is used in the treatment of hypertension, edema, and urinary tract disorders.
At what stage of a heart attack might you use a calcium channel blocker?
After a heart attack, especially in patients who cannot tolerate beta blockers.
What type of drug can be used to prevent migrane headaches?
Calcium channel blockers
What is the effect of Amlodipine on heart rate?
Other CCBs will slow the heart rate: used for treating abnormally rapid heart rhythms: Amlodipine has little effect on heart rate and so is safer to use in individuals with heart failure or bradycardia.
By what mechanism does Amlodipine cause vasodilation?
It stabilises voltage-gated L-type calcium channels in their inactive state.
By inhibiting the influx of calcium in smooth muscle cells, amlodipine prevents calcium-dependent myocyte contraction and vasoconstriction.
What type of drug is losartan? What are its basic effects effects on the body?
Losartan is an angiotensin-receptor blocker (ARB). It lowers blood pressure by antagonizing the renin-angiotensin-aldosterone system (RAAS); it competes with angiotensin II for binding to the type-1 angiotensin II receptor (AT1) and prevents the blood pressure increasing effcts of angiotensin II.
What common side effect may ACE inhibitors have, and what kind of drug is often prescribed instead?
What are the less common side effects of ACE inhibitors? (6)
ACE inhibitors can cause a dry cough in 1/3 patients so angiotensin-receptor blockers such as Losartan can be prescribed instead.
Other side effects:
- kidney failure. Kidney problems seen in 1/10 patients
- decrease in white blood cells
- swelling of tissues (angioedema)
- elevated blood potassium levels
- low blood pressure, dizziness in about 1/2 patients
- erection problems
What conditions can Losartan be prescribed for? (8)
Losartan may be used to treat
- hypertension,
- isolated systolic hypertension,
- left ventricular hypertrophy (enlargement)
- diabetic nephropathy.
It may also be used as an alternative agent for the treatment of
- systolic dysfunction (impaired ventricular contraction)
- myocardial infarction,
- coronary artery disease
- heart failure.
What is the Frank-Starling mechanism?
The Frank-Starling mechanism is the ability of the heart to change its force of contraction and therefore stroke volume in response to changes in venous return. So, the more venous return to the heart, the larger the stroke volume - this is becasue the ventricles respond to the higher pressure at the end of ventricular filling (a higher End Diastolic Pressiure EDP) by contracting with more force.
What is preload? What tends to be used instead of preload when assessing the heart function?
Preload can be defined as the initial stretching of the cardiac myocytes prior to contraction. Preload, therefore, is related to the sarcomere length. Because sarcomere length cannot be determined in the intact heart, other indices of preload are used such as ventricular end-diastolic volume (EDV) or pressure (EDP). For example, when venous return is increased, the end-diastolic pressure and volume of the ventricle are increased, which stretches the sarcomeres (increases their preload).
What is afterload?
Afterload can be thought of as the “load” that the heart must eject blood against. In simple terms, the afterload is closely related to the aortic pressure. More precisely, afterload is related to ventricular wall stress (σ)
why are vasodilators/blood pressure reducing drugs given in heart failure?
vasodilation reduces the afterload (closely related to aortic pressure) that the left ventricle has to pump blood against. Lower arterial pressure therefore improves the stroke volume(SV) of the heart and improves cardiac output.
What two major categories of high blood pressure are there? What is the definition of high blood pressure?
High blood pressure (hypertension) is designated as either essential (primary) hypertension or secondary hypertension and is defined as a consistently elevated blood pressure exceeding 140/90 mm Hg.
What is primary hypertension,
how common is it compared to secondary hypertension?
which ethnic group is it more common in?
In essential hypertension (95% of people with hypertension), no specific cause is found for the hypertension. Essential hypertension may run in some families and occurs more often in the African American population, although the genes for essential hypertension have not yet been identified.