level: Level 2
Questions and Answers List
level questions: Level 2
| Question | Answer |
|---|---|
| are the combination of an aglycone, or genin, and one to four sugars. | Cardiac glycosides |
| 1 is the pharmacologically active portion of the glycosides. 2 is frequently used to refer to the entire group of cardiac glycosides. | 1 aglycone 2 digitalis |
| Glycosides are obtained from __ | dried leaves of the foxglove, Digitalis purpurea (digitoxin) or Digitalis lanata (digitoxin, digoxin) and from the seeds of Strophantus gratus (ouabain). |
| is the most commonly used digitalis glycoside. The serum half-life is normally about 36 hrs and significantly prolonged by impaired renal function. It is not metabolized and is eliminated principally by the kidneys in almost unchanged form. | Digoxin |
| well absorbed 90%-100% from the GIT , the serum half-life is 5-7 days It is metabolized by the liver, and drugs that increase the activity of hepatic microsomal enzymes, such as phenobarbital and phenytoin, accelerate its metabolism. In contrast to digoxin, it is about 97% bound to plasma albumin. | Digitoxin |
| the effects of cardiac glycosides on the heart include: | 1 The dose of the agent 2 The interaction of direct cardiac effects with reflex changes in the autonomic and hormonal regulation of cardiovascular function. 3 The underlying cardiovascular pathophysiology |
| Effects of digitalis glycosides on the heart: | 1 Increased myocardial contractility 2 Increased myocardial contractility which causes an increase in MVO2 (myocardial volume O2) 3 Electrophysiologic activity- it indirectly incease the vagal tone of the heart 4 Heart rate. In CHF patients, digitalis slows the HR (a (-) chronotropic effect) due to a combination of vagal and sinoatrial (S-A ) nodes. Tachycardia is seen with excessive doses of digitalis (a (+) chronotropic effect). It has little effects on the heart rate of normal individuals. |