Anti-HTN drugs Fatema Pinky MAM Flashcards
What is hypertension?
Sustained raise of blood pressure ≥ 140/90 mmHg
What is pre-hypertension?
120-139/80-89 mmHg
What defines Stage 1 Hypertension?
140-159/90-99 mmHg
What defines Stage 2 Hypertension?
> 160/100 mmHg
What are the causes of hypertension?
Primary / essential / idiopathic; Secondary: Renal diseases, endocrine diseases, metabolic syndrome, drugs
What are the determinants of blood pressure?
Cardiac output * peripheral vascular resistance
BP= CO*PVR
What is the formula for blood pressure?
BP = CO x PVR
What factors affect cardiac output?
- Heart rate
- Stroke volume
What lifestyle changes can help lower high blood pressure?
- Eating a healthy, low-salt diet
- Losing weight
- Being physically active
- Quitting tobacco
What are the two main therapeutic approaches to hypertension?
- Decrease of PVR
- Decrease of CO
Name an anatomical site of action of antihypertensive drugs.
- Heart
- Kidneys
- Sympathetic nervous system
- Renin-angiotensin-aldosterone axis
- Vascular smooth muscle
What are the classes of antihypertensive drugs?
- Diuretics
- ACE inhibitors
- Angiotensin receptor blockers
- Calcium channel blockers
- Sympatholytics
- Vasodilators
- Renin inhibitors
What is the antihypertensive action of alpha-methyl dopa?
Acts as a pre-synaptic α2 agonist, inhibits release of NA from presynaptic neurons
What are the kinetic properties of alpha-methyl dopa?
Prodrug, 25% bioavailability, maximum action within 4-6 hours, duration of action 12-24 hours
List adverse effects of methyl dopa.
- Sedation
- Depression
- Increased prolactin secretion
- Rarely diarrhea and hepatitis
- Coombs positive hemolytic anemia
What is the mechanism of action of clonidine?
Directly stimulates non-neuronal α2 in arterioles, inhibits release of NA from presynaptic neurons
List uses of clonidine.
- Moderate hypertension
- Prophylaxis of migraine
- Postmenopausal syndromes
- Withdrawal symptoms of addictive drugs
- Attention deficit in hyperactive children
What are ganglion blockers?
Competitively block N receptor on post-ganglionic neurons, causing sympathoplegic effects
What are the adverse effects of ganglion blockers?
- Orthostatic hypotension
- Sexual disturbances
- Antimuscarinic effects (dry mouth, blurred vision)
What is the role of reserpine as an antihypertensive agent?
Blocks storage/release of noradrenaline from sympathetic neurons
What are the adverse effects of reserpine?
- Sedation
- Severe mental depression
- Extrapyramidal side effects
- Abdominal cramps
- Hyperacidity
List the alpha adrenergic blockers.
- Prazosin
- Terazosin
- Phenoxybenzamine
- Phentolamine
- Tolazoline
What is the antihypertensive action of prazosin?
Competitively blocks α1, dilates resistance and capacitance vessels, decreases PVR
List adverse effects of alpha adrenergic receptor blockers.
- Postural hypotension
- Palpitations
- Dizziness
- Headaches
- Syncope
What are the uses of beta adrenergic receptor blockers?
- Antihypertensive agents
- Angina
- Heart failure
- Arrhythmias
What are the kinetic properties of beta adrenergic blockers?
- Propranolol: short-acting, lipid soluble
- Atenolol: long-acting, water soluble
- Esmolol: very short duration of action
Explain the mechanism of antihypertensive action of beta blockers.
- Decrease heart rate and contractility
- Decrease renin release
- Alter sympathetic control at CNS level
List the adverse effects of beta blockers.
- Bradycardia
- Peripheral vascular insufficiency
- Bronchospasm
- Fatigue
- Depression
Why should beta blockers be avoided in diabetic patients?
Mask hypoglycemic symptoms, delay recovery from hypoglycemia, disturb diabetic control
What is the antihypertensive role of labetalol?
Blocks both α and β receptors, decreases blood pressure
What is the effect of diabetic control on hypoglycemic agents?
It hampers the hypoglycemic effect of insulin and other hypoglycemic agents
This can lead to disturbances in blood glucose levels.
What is the role of Labetalol in hypertension?
It blocks both α and β receptors, decreasing blood pressure by decreasing PVR with less altered CO and rate
Labetalol is safe in pregnancy and is useful in hypertensive emergencies and pheochromocytoma.
What is the composition of Labetalol?
It is a racemic mixture of 4 isomeric compounds
SS and RS are inactive; SR blocks α and RR blocks β with a β:α ratio of 3:1.
What is the primary action of Carvedilol?
It is a racemic mixture where S(-) is an α and non-selective β blocker, and S(+) is an α blocker
The ratio of α1 and β is 1:10.
List the uses of beta blockers.
- Hypertension (not as first line)
- Ischemic heart disease (IHD)
- Compensated heart failure
- After myocardial infarction (MI)
- Intravenous esmolol in hypertensive crisis
- Timolol in glaucoma
- Labetalol in hypertensive crisis
- Propranolol in migraine prophylaxis
- Carvedilol in heart failure
Beta blockers are used in various conditions but are not typically first-line for hypertension.
What is the mechanism of action of vasodilators?
They directly relax vascular smooth muscle
Some are used for long-term treatment while others are for short-term control of hypertensive emergencies.
What is the action of Hydralazine?
It interferes with IP3-evoked calcium release from the sarcoplasmic reticulum
Hydralazine is effective in dilating arterioles and is safer in pregnancy.
What is Minoxidil used for?
Moderate to severe refractory hypertension
It opens voltage-gated potassium channels leading to hyperpolarization and long-lasting arteriolar dilatation.
What are the adverse effects of Minoxidil?
- Tachycardia
- Retention of fluid
- Hirsutism
- Hypertrichosis
Hypertrichosis refers to excessive hair growth anywhere on the body.
What is Diazoxide’s mechanism of action?
It opens K+ channels leading to hyperpolarization and long-lasting arteriolar dilatation
Diazoxide is used in hypertensive emergencies and insulinoma.
What is the function of Sodium Nitroprusside?
It releases NO, stimulating guanylate cyclase and increasing cGMP
It dilates both arteries and veins, effectively reducing PVR and venous return.
What are the adverse effects of Sodium Nitroprusside?
- Hypotension
- Arrhythmia
- Accumulation of cyanide
- Metabolic acidosis
- Methhemoglobinemia
Cyanide poisoning can occur and is treated with sodium thiosulfate or hydroxocobalamin.
What is the initial goal for blood pressure reduction in hypertensive emergencies?
To decrease BP by 25% within minutes to 1 hour
Target to reach 160/100 mmHg within the next 2-6 hours.
List safe antihypertensives for use in pregnancy.
- Methyl dopa
- Hydralazine
- Labetalol
These medications are considered safe for managing hypertension during pregnancy.
What are preferred antihypertensive drugs for children?
ACE inhibitors (ACEIs) and Angiotensin II receptor blockers (ARBs)
These are often the first-line choices for managing hypertension in children.
What is the combination of drugs preferred post-myocardial infarction (MI)?
Beta blocker + ACE inhibitor (ACEI) or ARB
This combination helps in reducing mortality and improving outcomes after MI.
