Cardio L16 Drug therapy 2 Hypertension Flashcards
Secondary Hypertension
aetiology
- Renal or renovascular disease
- Endocrine disease e.g.
• Phaechomocytoma (tumour of arterial medulla)
• Cushings syndrome (excess cortisol)
• Conn’s Syndrome (excess aldosterone)
• Acromegaly (excess growth hormone)
• Hypo/hyper thyroidism
• Pregnancy - Co-arctation of the aorta
- Iatrogenic
• Hormonal/ oral contraceptive
• NSAIDs
Typical feature of hypertensive heart disease
Left ventricle thickening
Treatment: 7 example
- Thiazides
- Ca2+ channel blockers
- ACE inhibitors
- α 1-adrenoceptor blockers:
- Ang II receptor blockers:
- K+ channel activators:
- α –methyldopa:
Thiazides
Class of diuretics control hypertension (in part) by blocking the Na+ - Cl_ symporter in first part of DCT.
Thiazides function
- Diuresis follows the increased NA load at CD
- This increases K loss due to increased tubule Na and aldosterone – dependent Na+-K+ exchange.
- Reduced Uric acid, Ma2+, Ca2+ excretion.
- Note “thiazide” can also be used for drugs with similar action but not thiazide structure (e.g. chlorthalidone and metolazone).
Thiazides Additional action
• Vasodilator action
Thiazides Side effects
- Electrolyte disturbances
- Decrease glucose tolerance
- Can reduce efficacy of anticoagulants and uriosurics
- Can increase LDL and cholesterol
Thiazides Examples
- Hydrochlorothiazide
* Bendroflumethazide
Ca2+ channel blockers function
Want to dilate periphery to:
- Reduce peripheral resistance
- Reduce filling pressure
Ca2+ channel blockers examples
- Dihydropyridines →
• Nifedipine
• Amlodipine
Ca2+ channel blockers side effects
- Peripheral oedema, dizziness
3. Generally contraindicated in HF, but non-DHP may be useful (e.g. verapamil) in such cases.
ACE inhibitors: function
Long-term control of BP involves renin-angiotensin system.
Angiotensin is
A vasoconstrictor
Examples of prototypic drugs
Captopril
Enalapril
Effects in 2 phases ACE inhibitors
- Rapid due to direct anti- ANG II effect
2. Slower due to blood volume effect and control of thirst.