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9 Cards in this Set
- Front
- Back
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1. Chemically, what is levothyroxine(T 4 )?
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• Thyroid hormones T 4 and T 3 are iodinated derivatives of tyrosine.
• L-Tyrosine is the precursor to thyroid hormones, T4 and T3 • Synthesis and storage of thyroid hormone o Occurs as part of the synthesis of thyroglobulin, a large glycoprotein o Hormone stored in follicle lumen of thyroid gland |
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2. Describe the history and development of T4
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• Approx 20 million people take
• #3 most widely prescribed drug in US • Early partial thyroidectomies required medical treatment • Early thyroid hormone preps were thyroid gland extracts from sheep • Edward Kendall isolated thyroxine from thyroid extract in 1914 • In 1950’s T 3 was discovered (Triiodothyronine) • T 4 found to be better because it acts on its own and is converted to T3 in body. • 1960’s found that the sodium form of T 4 is better absorbed than the non-salt form of T4. |
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3. Why are not generics of T4 used more often?
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• Generic sodium levothyroxine does not seem to work as consistently as Synthroid.
• Many endocrinologists think that the differences between generics and Synthroid may be over 12%. • Differences in the way tablets are compounded may account for differences in absorption rates. |
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4. Describe the chemical difference between T3 and T4.
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• One has 3 iodides the other 4 iodides
• Sodium Levothyroxine (T 4 , Synthroid) • Sodium liothyronine ( T 3, Cytomel) • Both synthetically prepared by industry o sodium levothyroxine preferred agent |
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5. List the important adverse effects of Synthroid.
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• palpitations, tachycardia
• nervousness, sweating • increased appetite • weight loss – not to be used in weight control programs |
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6. Describe the use of epinephrine in patients on Synthroid.
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• Epinephrine as vasoconstrictor – any problems if given to Synthroid patients ??
• Not if patient is well controlled on Synthroid • So ask the patient under what dose they are taking the synthroid because they might still be in titration and the final dose is not established yet. If they have been in hormone for years they don’t have side effect. • If synthroid is given in high dose, it can give palpitation and increase heart rate. If we give epinephrine that just started the hormone treatment (3 months or less) we better wait because we can worsen the symptoms if we give them epinephrine in anesthesia. o So make sure you only give epinephrine when the hormonal dosis for the patient is established. Don’t do it at the beginning. |
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7. Describe the use of T4 in medicine
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• Use - replacement or supplement therapy in hypothyroidism
o Idiopathic hypothyroid condition Partial thyroidectomy to treat hyperthyroidism Suppression of pituitary TSH • Adult dose - 100 to 200 micrograms daily • Mechanism - affects DNA transcription and stimulates protein synthesis; promotes gluconeogenesis, mobilizes glycogen stores, increases basal metabolic rate. |
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8. List three drugs used to treat hyperthyroidism
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• Propylthiouracil
o Used for palliative treatment of hyperthyroidism o Blocks oxidation of iodine in thyroid gland o Blocks synthesis of T 4 and T 3 o Side effects include skin rash, nausea and agranulocytosis • Iodides o saturated solution of potassium iodide o mechanism-not clear; probably reduces secretion of thyroid hormone o Used in conjunction with propylthiouracil to prepare hyperthyroid patients for surgery • Radioactive Iodide I 131 o beta ray emission (15-30 millicuries) destroy thyroid tissue o Diagnostic dose- about 30 microcuries emit gamma rays useful in estimating activity of the gland. |
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9. Describe the dental considerations of patients with thyroid disease.
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Think about interactions with thyroid hormone with epinephrine when administrating local anesthesia.
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