Pharmacology - Drug Condition Questions

This category covers a lot of drugs and a lot of questions. They can be categorized as:

1. Questions asking about which drug from a list might be used to treat a certain condition:

hypertension:
1) Diuretics such as the high ceiling or loop-acting diuretic, furosemide;
2) Beta-blockers such as propranolol or the cardioselective beta blocker metoprololor atenolol
3) Alpha-1 blockers such as prazosin,
4) Centrally acting adrenergic drugs such as methyldopa or clonidine
5) Neuronal blockers such as guanethidine (reserved for severe hypertension)
6) Angiotensin converting enzyme inhibitors such as Captopril, lisinopril angina: Nitroglycerin, sometimes propranolol, calcium channel blockers such as verapamil

arrhythmias:
1) Lidocaine (ventricular arrhythmias),
2) Phenytoin (to reverse digitalis induced arrhythmias),
3) Quinidine (supraventricular tachyarrhythmias, atrial fibrillation),
4) Verapamil (supraventricular tachyarrhythmias, paroxysmal tachycardia, atrial fibrillation),
5) Digitalis (atrial fibrillation, paroxysmal tachycardia)
6) Propranolol (paroxysmal tachycardia)

angina: Nitroglycerin, sometimes propranolol, calcium channel blockers such as verapamil

Congestive heart failure: Glycosides such as digitalis, digoxin, ACE inhibitors such as captopril

 

2. The second major category of questions concerns mechanism of action of the various agents:

Antiarrhythmics: Remember problem is that the heart beats irregularity
a. Type 1A agents such as quinidine: acts by increasing the refractory period of cardiac muscle
b. Type 1B agents such as lidocaine decrease cardiac excitability
c. When digitalis is used for atrial fibrillation it acts by decreasing the rate of A-V conduction

Antiangina drugs: problem is insufficient oxygen to meet demands of myocardium
a. Nitroglycerin increases oxygen supply to the heart by a direct vasodilatory action on the smooth muscle in coronary arteries
b. Propranolol reduces oxygen demand by preventing chronotropic responses to endogenous epinephrine, emotions and exercise.
c. Calcium channel blockers decrease oxygen demand by reducing afterload by reducing peripheral resistance via vasodilation

Antihypertensives: Remember, most drugs have the ultimate effect of reducing peripheral resistance via vasodilation

ACE inhibitors: Captopril blocks the enzyme which converts angiotensin I to angiotensin II. The latter is a potent vasoconstrictor (administration of angiotensin will result in an elevation of blood pressure).

Adrenergic Agents:
a. Prazosin: selective alpa-1 blocker, inhibits binding of nerve induced release of NE resulting in vasodilation
b. Methyldopa: acts centrally as a false neurotransmitter stimulating alpha receptors to reduce sympathetic outflow resulting in vasodilation
c. Clonidine: selective agonist stimulates alpha-2receptors in the CNS to reduce sympathetic outflow to peripheral vessels resulting in vasodilation
d. Propranolol: nonselective beta blocker reduces cardiac output and inhibits renin secretion
e. Metoprolol: selective beta-1 blocker, reduces cardiac output

Diuretics: decrease the renal absorption of sodium, thus resulting in fluid loss and a reduction in blood volume. This decreases the work the heart has to pump. Also have weak dilatory action. Types of diuretics which may be mentioned include:
a. Thiazides: chlorothiazide
b. High-ceiling or loop acting: furosemide
c. Potassium sparing: spironolactone

Congestive heart failure drugs:
a. Cardiac glycosides such as digitalis or digitoxin are effective because they have a positive inotropic effect, increasing the force of contraction of the myocardium. This is achieved by an inhibition of Na+, K+ ATPASE leading to increased calcium influx. Digitalis therapy reduces the compensatory changes that are associated with congestive heart failure such as increased heart size, rate, edema, etc.