Question 1

How does Strophanthus gratus work on the heart?

Accepted Answer

Strophanthus gratus contains cardiac glycosides, primarily ouabain (g-strophanthin), which inhibit the sodium-potassium ATPase pump in cardiac cells. This inhibition increases intracellular sodium, which reduces calcium extrusion via the sodium-calcium exchanger, ultimately raising intracellular calcium concentrations. The elevated calcium strengthens cardiac muscle contractions and slows heart rate through effects on the electrical conduction system. This mechanism is similar to digoxin but ouabain acts more rapidly. Evidence level: C.

Question 2

What are the drug interactions of Strophanthus gratus and ouabain?

Accepted Answer

Strophanthus gratus cardiac glycosides have significant drug interactions. Concurrent use with other cardiac glycosides like digoxin increases toxicity risk. Potassium-depleting diuretics, corticosteroids, and laxatives potentiate cardiac glycoside toxicity. Calcium supplements and calcium channel blockers may increase arrhythmia risk. Medications like quinidine, verapamil, and amiodarone can alter glycoside levels. Beta-blockers and other rate-lowering drugs may cause dangerous bradycardia. Medical supervision is essential for any cardiac glycoside therapy. Evidence level: C.

Question 3

What is the safe dosage of Strophanthus gratus?

Accepted Answer

There is no safe self-administration dosage for Strophanthus gratus. The plant and seeds are highly toxic and have been historically used as arrow poison. Pharmaceutical ouabain is administered only intravenously in hospital settings under strict medical supervision for acute cardiac conditions. The narrow therapeutic window means the difference between therapeutic and toxic doses is extremely small. Any use outside medical settings carries significant risk of fatal cardiac toxicity. Evidence level: C.

Question 4

Is Strophanthus gratus safe during pregnancy?

Accepted Answer

No, Strophanthus gratus is absolutely unsafe during pregnancy and breastfeeding. The cardiac glycosides, particularly ouabain, can cross the placental barrier and may cause fetal harm including cardiac abnormalities. The potent effects on cardiac function pose serious risks to both mother and developing fetus. These compounds may also pass into breast milk. Women who are pregnant, planning pregnancy, or breastfeeding must avoid this herb entirely. Evidence level: C.

Question 5

What are the side effects of Strophanthus gratus ingestion?

Accepted Answer

Strophanthus gratus can cause severe and potentially fatal cardiac toxicity. Side effects include dangerous heart rhythm abnormalities, severe bradycardia, heart block, and cardiac arrest. Non-cardiac effects include nausea, vomiting, diarrhea, visual disturbances, confusion, and headache. The plant has a narrow therapeutic window, meaning toxic effects can occur at doses only slightly higher than therapeutic ones. Kidney disease increases toxicity risk. Immediate medical attention is required for any suspected exposure. Evidence level: C.

Strophanthus Gratus Herb

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