Digoxin

Digoxin

It is also known as digitalis and is extracted from the plant Digitalis lanata which is found in Eastern Europe.
Other names: Lanoxin, Digitek, and Lanoxicaps. It is also available as a 0.05 mg/mL oral solution and 0.25 mg/mL or 0.5 mg/mL injectable solution.

Its main cardiac effects are
• Negatively chronotropic - i.e. slowing the heart rate by decreasing conduction of electrical impulses through the AV node, making it a commonly used antiarrhythmic agent in controlling the heart rate during atrial fibrillation or atrial flutter.
• Positively inotropic - i.e. increasing the force of heart contraction via inhibition of the Na+/K+ ATPase pump

ATPase controls movement of calcium, sodium and potassium into heart muscle. Calcium controls the force of contraction. Inhibiting ATPase increases calcium in heart muscle and therefore increases the force of heart contractions.
Digoxin is usually given by mouth, but can also be given by IV injection in urgent situations (the IV injection should be slow, heart rhythm should be monitored). The half life is about 36 hours; digoxin is given once daily, usually in 125 μg or 250 μg dosing. Following drug administration, a 6- to 8-hour tissue distribution phase is observed.

This half life is only present for those with normal renal function, as this drug is metabolized through the kidneys.
Digoxin blood levels are used for adjusting doses in order to avoid toxicity. The usual starting dose is 0.0625-0.25 mg daily depending on age and kidney function. The dose may be increased every two weeks to achieve the desired response.

Side Effects:
Common side effects include nausea, vomiting, headache, dizziness, skin rash, and mental changes. Many digoxin side effects are dose dependent and happen when blood levels are over the narrow therapeutic range. Visual disturbances (blurred vision or yellow/green halos around objects), fast/slow/irregular heartbeat and overdosage may occur if patient is dehydrated.