pharma 2

What are the structures and source of digitalis?

- Source: Extracted from the Foxglove plant.

- Structure: Consists of sugar (glycone, affects kinetics) and non-sugar part (aglycone or genin with

steroid nucleus and lactone ring - active part).

What are the mechanisms of action of digitalis?

Inhibits Na+/K+-ATPase leads to increases intracellular Na+ leads to decreases Na+/Ca²+

exchange leads to increases intracellular Ca²+ leads to increases contractility

What are the mechanical and electrical effects of digitalis on cardiovascular system?

- Mechanical: increases contractility, decreases HR, decreases preload/afterload, diuretic effect,

decreases heart size.

- Electrical: Early - increases vagal tone ( decreases HR, AV conduction); Late - arrhythmias

(VPBs, tachycardia, VF).

What is the effect of digitalis on other organs?

CNS: nausea, vomiting, hallucinations, colored vision.

- Smooth muscles: direct contraction.

- Renal: natriuretic.

- Endocrine: gynecomastia.