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33 Cards in this Set
- Front
- Back
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what is levothyroxine similar to
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T4
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is thyroid hormone water soluble and why
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thyroid hormone is insoluble in water due to iodines being so lipophilic that even the salt form is insoluble
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what are the properties of levothyroxine
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sensitive to light, air, heat, very hydroscopic
insoluble amphoteric highly protein bound |
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why is levothyroxine unstable
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due to excipients
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what are the iodine locations on levothyroxine
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3,5, 3 PRIME, 5 PRIME
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what is the shelf life and bioavalability of levothyroxine
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shelf life = 2 year
bioavailability= 50-80% |
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what are the properties of liothyronine
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WATER insoluble
unstable in light, heat, air, very hydroscopic WELL ABSORBED FROM GI |
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what is liothyronine similar to
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T3
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what are the main differences between levothyronine and levothyroxine
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levothyroxine is more acidic than levothyronine due to the halogens being electron withdrawing groups
levothyroxine has a slower onset of action and a longer duration |
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why was amour thyroid replaced
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due to variation in T3/T4 content
absorption was erratic and incomplete |
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what are the antithyroid agents
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perchlorate (CLO4-)
isothiocynate (SCN) thiocynate (CNS) pertecchnetate (TCO4-) PTU MMI genistein goitrogens |
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what does SCN and CNS do
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they are antithyroid agents
SCN - inhibits iodine transport SCN and CNS are found in cabbage, salad green,s radishes, turnips |
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what does Pertechnetate do
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antithyroid agent used in Tc99 imaging
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what are the properties of Propylthiouracil
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inhibits peroxidase
inhibits (5 PRIME DE-IODINASE) T4 > T3 insoluble in water light sensitive can resonate and aromatize ring (due to nitrogens being bound to an H) |
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what is PTU light sensitive
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due to it being a nitrogenous base
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what are the properties of Methimazole
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inhibits peroxidase
water soluble light sensitive 10x more potent than PTU DOESNT INIHIBIT (5 PRIME DE-IODINASE) T4 > T3 |
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what is the half life of PTU and MMI
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PTU = 75 mins
MMI = 4-6 hrs |
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what are the similarities between PTU and MMI
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NO EFFECT ON HORMONE RELEASE
inhibit peroxidase antithyroid agents used to treat hyperthyroidism light sensitive BOTH ARE THIOUREAS OR THIONAMIDES |
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what are the differences between PTU and MMI
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MMI is water soluble PTU is water insoluble
MMI is 10x more potent than PTU PTU has a HL of 75 mins and must be given as multiple doses while MMI has a HL of 4-6 hrs and can be give once daily PTU is prefered in cases of lactating and pregnancy PTU IS THE DRUG OF CHOICE WHEN TREATING THYROID STORM PTU inhibits T4/T3 conversion while MMI does not |
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what is the drug of choice when treating thyroid storm
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PTU
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what are the properties of genistein
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inhibits thyroid peroxidase
found in soy beans and instant food products ISOFLAVONE |
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what are the similarities between T4 and T3
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both are water insoluble
amphoteric sensitive to heat, air, light, very hydroscopic optically active |
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what are the differences between T4 and T3
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T4 has a longer duration than T3
T4 is more acidic |
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why does T4 have greater serum protein binding with T4 than T3
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due to it being more acidic
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what is the pKa of T4 and T3
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T4 = 6.7
T3 = 8.5 |
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what % of rT3 and T3 are made
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T3 = 33%
rT3 = 40% |
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what happens if Oxygen is removed
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compound becomes inactive b/c the aromatic rings will then be on the same plane and in order to be active they must be perpindicular
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what happens if oxygen is replaced with CH2 or Sulfure
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makes the compound highly active
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what happens on the Phenolic ring if 3' 5' replaced by OH or Nitro
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molecule becomes less active
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rank the activity for the Phenolic ring
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I>Br>Cl>F
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replacement of the Phenolic OH with what will decrease activity
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NH2 or CH3
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replacement of the Phenolic OH with what will increase activity
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OCH3 and H
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replacement of 3, 5 iodine on the Alanine bearing ring decreases its activity drasticaly
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Hydrogen
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