Bioassay of Digitalis (Cardiac Glycosides)

• Bioassay of Digitalis (Cardiac Glycosides): Measures potency using frog or cat heart preparation.
• Bioassay of Digitalis (Cardiac Glycosides): Evaluates cardiac activity via inotropic effect comparison.

Principle of Bioassay of Digitalis (Cardiac Glycoside)

• Digitalis (e.g., digoxin, digitoxin) increases the force of cardiac contraction and can induce characteristic arrhythmias or lethal effects in overdose.
• The bioassay detects either the inotropic effect (strength of heartbeat) or the toxic/lethal effect in an experimental model.

Methods

1. Pigeon Method (Historical)

• Procedure:
  1. Inject known doses of standard digitalis and test sample into pigeons.
  2. Observe for the “death in diastole” phenomenon (a classic sign of digitalis toxicity).
• Potency Determination: Compare the lethal doses (LD50).

2. Frog Heart or Guinea Pig Heart Method (Isolated Heart)

• Procedure:
  1. Use an isolated perfused frog/guinea pig heart.
  2. Administer incremental doses of standard vs. test digitalis.
  3. Monitor for changes in contractility or typical arrhythmias (e.g., AV block, bigeminy).
• Potency Determination: Compare the dose that causes a standardized endpoint (e.g., 50

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