Hypertensive Propranolol

Hypertensive Propranolol

Discuss Propranolol In Detail. Add A Note On Dental Consideration In Hypertensive Patient.
Answer:

Hypertensive Propranolol Actions

• Cardiovascular System
  • Heart: Propranolol decreases heart rate, force of contraction, and cardiac output. It prolongs systole by retarding conduction so that the synergy of contraction of ventricular fibers is disturbed. The effects on a normal resting subject are mild but become prominent under sympathetic overactivity. Cardiac work and oxygen consumption are reduced as the product of heart rate and aortic pressure decreases.
  • Blood vessels: Propranolol blocks vasodilatation and falls in BP evoked by isoprenaline and enhances the rise in BP caused by adrenaline. On prolonged administration BP gradually falls in hypertensive subjects but not in normotensive. Total peripheral resistance is increased initially and cardiac output is reduced-little change in BP with continued treatment, resistance vessels gradually adapt to chronically reduced cardiac output so that total peripheral resistance decreases—both systolic and diastolic BP fall.
• Respiratory Tract: Propranolol increases bronchial resistance by blocking β2 receptors.
• Local Anesthetic: Propranolol is as potent a local anesthetic as lidocaine, but is not clinically used for this purpose because of its irritant property.
• Metabolic: Propranolol blocks adrenergic ally-induced lipolysis and consequent increase in plasma-free fatty acid levels. Plasma triglyceride level and LDL/HDL ratio is increased during propranolol therapy.
• Skeletal Muscle: Propranolol inhibits adrenergic ally-provoked tremors. This is a peripheral action exerted directly on the muscle fibers. It tends to reduce exercise capacity by attenuating the increase in blood flow to the exercising muscles as well as by limiting glycogenolysis and lipolysis which provide fuel to working muscles.

Propranolol in Hypertension: Mechanism of Action and Benefits

Indications Or Therapeutic Uses

• Essential Hypertension: Propranolol is used alone or can be combined with either a diuretic or α-adrenergic blocking drug. The fall in blood pressure, when used alone, is gradual and without postural hypotension.
• Ischemic Heart Disease: It decreases the workload on the heart, diminishes myocardial oxygen demand, and increases exercise tolerance; hence β-blockers benefit patients having angina of effort. The drug should be given continuously and not merely when an attack occurs.
• Myocardial Infarction: β-blockers significantly decrease the incidence, recurrence, and mortality in cases of myocardial infarction after long-term use.
• Cardiac Arrhythmias: Propranolol is effective in all supraventricular tachycardias associated with high levels of circulating catecholamines as occurs with the use of certain general anesthetics like halothane, in digitalis toxicity, pheochromocytoma, and thyrotoxicosis. The beneficial effect is mainly due to an increase in the refractory period of the AV node and direct membrane stabilizing action.
• Congestive cardiac failure: Propranolol should be introduced gradually and should be maintained for a long time. The drug has the tendency to retard the progression of congestive cardiac failure.
• Dissecting aortic aneurysm: It reduces the cardiac contractile force and aortic pulsation. It also reduces the rate of development of pressure at the time of systole.
• Pheochromocytoma: The drug in pheochromocytoma control cardiac manifestations such as tachycardia and arrhythmia.
• Hyperthyroidism: The drug controls the sign and symptoms produced due to hyperthyroidism without affecting the thyroid status.
• Anxiety: Propranolol has anti-anxiety effects and controls palpitation, tachycardia, tremor, sweating, etc.
• Essential tremors: Propranolol provides relief in cases with essential tremors.
• Glaucoma: It reduces intraocular pressure by decreasing the production of aqueous humor.

Propranolol for Hypertension: Dosing, Side Effects, and Contraindications

Adverse Effects And Contraindications

• Bronchoconstriction: This is of little significance in normal persons but in asthmatics, or in patients with bronchitis or emphysema this effect could be life-threatening.
• Cardiac Failure: Cardiac patients always need a degree of sympathetic drive to support the heart to maintain proper cardiac output. β-blockers block this support and may aggravate heart failure.
• Hypoglycemia: The sympathetic response to hypoglycemia is a safety device that warns patients of diabetes to eat sugar, by producing symptoms like tachycardia, cold sweating, and tremors. β-blockers mask these symptoms and delay recovery from hypoglycemia.
• Bradycardia: Lowering of heart rate to 55 beats/min, as it occurs with β-blockers at times, can lead to life-threatening bradyarrhythmias and heart block.
• Cold Extremities: This results from a loss of receptor-mediated cutaneous vasodilatation in the extremities.

Drug Interactions

• Hypertensive patients receiving propranolol are very sensitive to the pressor responses of epinephrine because simultaneous blockade of vasodilatory β2 receptors provides an unopposed vasoconstricting action of epinephrine on α receptor.
• Enzyme inducers decrease the plasma concentration of propranolol.
• β-blockers impair the clearance of lignocaine and thus may increase its bioavailability.

Propranolol as an Antihypertensive: Role in Blood Pressure Control

Dental Consideration In Hypertensive Patient

• Detail case history of the patient is taken.
• Before the dental procedure, it should be confirmed that the patient is on antihypertensive therapy. If a patient is hypertensive and is not on therapy he/she should be immediately sent to consult a physician.
• Just before following the dental procedure blood pressure of the patient is checked. It should be 120/80 mm of Hg, i.e. within its normal limits.
• While giving anesthesia, the anesthetic agent should be used which is without epinephrine, as epinephrine constricts blood vessels and lead to an increase in blood pressure.
• After a surgical dental procedure, the surgical area should be properly cleaned and is sutured.
• Patients who are on alpha-blockers and vasodilators may undergo postural hypotension. So they are advised to take care during getting up from the dental chair.