Antihypertensive Drugs : Definition, Classification, Example, Mechanism of Action, Uses, Side Effects, Contraindications, & Interactions
- Antihypertensive drugs are agents used to lower BP in hypertension.
- Thiazides and related drugs (chlorthalidone, etc.) are the diuretic of choice in uncomplicated hypertension.
- Ethacrynic acid
2. ACE inhibitors
- The ACE inhibitors are one of the first choice drugs in all grades of essential as well as renovascular hypertension (except those with bilateral renal artery stenosis).
- Most patients require relatively lower doses ( enalapril 2.5-10 mg/ day or equivalent) which are well tolerated.
- Used alone they control hypertension in ∼50% patients, and addition of a diuretic / β-blocker extends efficacy to ∼90%.
- Dry persistent cough is the most common side effect requiring discontinuation of ACE inhibitors.
3. Angiotensin receptor (AT1) blockers (ARBs)
- ARBs are remarkably free of side effects. Because they do not increase kinin levels, the ACE inhibitor related cough is not encountered.
- Azilsartan medoxomil
4. Calcium channel blockers (CCBs)
- Calcium channel blockers (CCBs) are another class of first line antihypertensive drugs.
- The onset of antihypertensive action is quick.
- With the availability of long acting preparations, most agents can be administered once a day.
Advantages of CCBs are:
- Monotherapy with CCBs is effective in ∼50% hypertensive patients; their action is independent of patient’s renin status, and they may improve arterial compliance.
- Do not compromise haemodynamics.
- No CNS effects; cerebral perfusion is maintained.
- No contraindication for asthma, angina (especially variant) & PVD patients: may benefit these conditions.
- No impairment in renal perfusion.
- No effect on male libido.
- No deleterious effect on plasma lipid profile, uric acid level & electrolyte balance.
- No/minimal effect on quality of life.
- No adverse effects on foetus; can be used during pregnancy (but can weaken uterine contractions during labour).
- They are mild antihypertensives; do not significantly lower BP in normotensives.
- The hypotensive response to β-blockers develops over 1-3 weeks and is well sustained.
- All β-blockers, irrespective of associated properties, exert similar antihypertensive effect.
6. β+α- blockers
7. α- blockers
8. Central sympatholytics
- Hydralazine/ Dihydralazine
Arteriolar + Venous dilators
- Sodium nitroprusside
10. Renin inhibitors