Question

What is the purpose of a thyroid panel with amiodarone ?

What is nitrate tolerance?

What are the contraindications to therapy with Coumadin?

What classes of medications are used in the treatment of congestive heart failure?

Answer 1

1)Purpose of thyroid panel with Amiodarone is to identify thyroid dysfunction induced by Amiodarone.

▪︎Amiodarone is rich in iodine content

▪︎Increase in iodine content can lead to :

• Abnormal changes in thyroid hormone profile without thyroid dysfuction
• Amiodarone induced hypothyroidism - a)occurs in areas with high intake of iodine, b)Occurs when thyroid gland is not able to escape wolff chaikoff effect (autoregulatory phenomenon which inhibits thyroid hormone production when iodine levels are high ), c)stopping Amiodarone or giving thyroid hormones is the treatment.
• Amiodarone induced thyrotoxicosis- a)in areas with low intake of iodine , b)iodine leads to increased synthesis of thyroid hormones or destructive thyroiditis with released preformed hormones, c)Treatment : Thinamides, potassium perchlorate and glucocorticoids.

2)Nitrate tolerance :

• Nitrate tolerance means loss of its hemodynamic and anti-ischemic effects when administered chronically
• Counter regulatory vasoconstrictor effects occur by elevating the levels of nor adrenalin , angiotensin II , oxidative stress etc
• Pseudo tolerance : occurs at systemic level by neurohormonal counter regulation and increased intravascular volume
• True vascular tolerance : occurs at vascular level - increase in phosphodiesterase activity(decreases nitrate induced vasodilatation ) ,inhibition of nitrate biotransformation , inhibition of guanylate cyclase.
• Tolerance can be prevented by intermittent nitrate administration

3)Coumadin is an anticoagulant and it is contraindicated in :

• Hepatic and renal diseases
• Uncontrolled blood pressure
• Uncontrolled bleeding and open wounds
• In pregnancy Coumadin crosses placenta and can causes fetal hemorrhage

4)Classes of medication used in congestive heart failure :

• Beta blockers : Metaprolol , bisoprolol etc
• ACE inhibitors : Captopril
• Angiotensin receptor blockers : Losartan etc
• Cardiac glycosides : Digoxin , lanoxin
• Diuretics : Furosemide
• Aldosterone antagonists : Spironolactone