introduction to antithyroid, definition, antithyroid drugs, classification, mechanism of action advantages and disadvantages,

1. ANTITHYROID
DRUGS
Presented by
Ms. Sayali V. Kurjekar
(Dept. Of Pharmacology)
Mr. Aayush D. Hasoriya
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2. CHAPTERS
• CHAPTER I : INTRODUCTION
• CHAPTER II : DEFINITION
• CHAPTER III : CLASSIFICATION OF ANTI-THYROID
• CHAPTER IV : MECHANISM OFACTION
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3. I. INTRODUCTION
• Basically thyroid disease can be classified into 2 types
1. Hypothyroidism
2. Hyperthyroidism
HYPO-THYROIDISM: It is a condition in which the thyroid glands don’t produce
enough hormones.
HYPER-THYROIDISM: It is a condition in which the thyroid gland produces excess hormones.
(use of antithyroid drugs)
CHAPTER I : INTRODUCTION
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4. II. DEFINITION
What are antithyroid agents?
 These drugs are used to treat hyperthyroidism to reduce the excessive thyroid activity before
surgery and to treat and maintain patients not having surgery.
 That is to lower and maintain the increased level of T3 and T4 in blood.
CHAPTER II: DEFINITION
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5. III. CLASSIFICATION OFANTI-THYROID
INHIBIT
HORMONES
SYNTHESIS
• PROPYLTHIOURACIL
• CARBIMAZOLE
• METHIMAZOLE
INHIBIT
IODIDE
TRAPPING
{IONIC
INHIBITORS}
• THIOCYNATE [-SCN]
• PERCHLORATES (-Clo4)
• NITRATES {-NO3)
INHIBIT
HORMONE
RELEASE
• IODINE
• IODIDES OF
SODIUM
• POTASSIUM
• ORGANIC IODIDE
DESTROY
THYROID
TISSUE
• RADIO ACTIVE
IODINE
ANTITHYROID
CHAPTER III : CLASSIFCATION OF ANTI-THYROID DRUGS
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6. IV. MECHANISM OF ACTION
• Drugs used:
1. Propylthiouracil
2. Carbimazole / methimazole
• MECHANISM OF ACTION
1. INHIBIT PEROXIDASE ACTION
Thyroid cell
• In thyroid cells, there is the presence of peroxidase which converts iodide into iodine. These
drugs inhibit the action of peroxidase.
• Carbimazole after metabolism gets converted into active metabolite i.e. methimazole.
• Both propylthiouracil and carbimazole inhibit the action of peroxidase which
stops the conversion.
• As we know that iodine is important for the conversion so the process stops here itself.
CHAPTER IV : MECHANISM OF ACTION
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PEROXIDASE
H2O2 I+
I-
1. INHIBIT HORMONES SYNTHESIS

7. • 2. INHIBITION OF COUPLING PROCESS
• Thyroglobulin contains tyrosine bases
• We know that, if tyrosine base contains 2 Iodine it is
known as DIT, and if contains 1 Iodine then
it is called MIT.
• If DIT combines with MIT, T3 is formed And if DIT
combines with DIT, T4 is formed
• The above process is known as coupling.
• And this drug inhibits the coupling process. therefore,
results in the inhibition of the synthesis of
thyroid hormones
Thyroid cell : thyroglobulin binds with DIT and MIT
CHAPTER IV : MECHANISM OF ACTION
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8. 3. INHIBITION DEIODINATION OF T4
• Drug used is only propylthiouracil
• T3 is more potent than T4, therefore T4
is gets converted into T3 by the process
of deiodination.
• Propylthiouracil inhibits deiodination,
which falls level of T3.
Target cell
CHAPTER IV : MECHANISM OF ACTION
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T3
T3
T3
T4
T3
T3
DEIODINATION

9. PROPYLTHIOURACIL MTHIMAZOLE /
CARBIMAZOLE
PLASMA HALF LIFE 1-2 HOURS 8 HOURS
EFFECT OF SINGLE DOSE
LAST
8 HOURS (2-3 DOSE / DAY) ENTIRE DAY (1DOSE / DAY)
USES HYPERTHYRODISM:- GRAVES DISEASE, GOITER
ADVERSE EFFECTS OF
THIOAMIDES
HYPOTHYRODISM AND GOITRE can occur due to over
treatment
CHAPTER IV : MECHANISM OF ACTION
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10. 2.INHIBIT IODIDE TRAPPING ( IONIC INHIBITORS)
Drug used : THIOCYNATE [-SCN],
PERCHLORATES(-Clo4), NITRATES(-No3)
MECHANISM OF ACTION
• The main component required from the blood
vessel is Iodide which enters into the follicle by a
symporter known as Sodium Iodide symporter
(SOD-IODIDE Symporter)
• The above drugs block SOD-IODIDE symporters,
therefore the Iodide can not enter the follicle and
the process is stopped here itself
BLOOD
VESSELS
FOLLICLE
SYMPORTER
CHAPTER IV : MECHANISM OF ACTION
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11. THIOCYNATE [-SCN] PERCHLORATES(-Clo4)
ADVERSE EFFECT • Kidney Toxicity
• Liver Toxicity
• Bone Marrow Toxicity
• Brain Toxicity
• Produce Rashes
• Fever
• Aplastic Anemia ( body stop
producing new blood cells)
• Agranulocytosis ( Lower WBC)
Clinically not used
CHAPTER IV : MECHANISM OF ACTION
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12. 3.INHIBIT HORMONE RELEASE
Drug used: Iodine, Iodides of sod,
potassium, org iodide
MECHANISM OF ACTION
• Excess amount of iodine blocks transport
of itself, that is it blocks sodium
iodine symporters.
• It also blocks by thyroid constipation
Blood vessel follicle
CHAPTER IV : MECHANISM OF ACTION
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13. IODINE IODIDES OF SOD,POTASSIUM,ORG IODIDE
ACUTE ADVERSE
EFFECT
• Swelling of lips and eyelids
• Fever
• Joint pain
• Deficiency of platelets
CHRONIC
ADVERSE EFFECT
• Inflammation of mucous membrane
• Salivation
• Sneezing
• GI disturbance
CHAPTER IV : MECHANISM OF ACTION
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14. 4.DESTROY THYROID TISSUE
• Drug use : Radio active Iodine
• MECHANISM OF ACTION
• The thyroid gland is bombarded
with Radioactive iodine which
results in destroy of thyroid cells.
• As the cells are damaged now
they can’t perform their function
i.e. they can’t produce T3 and T4
bombarding of Radioactive
isotope
( radioactive Iodine)
Thyroid Gland Destroy of
Thyroid cells
CHAPTER IV : MECHANISM OF ACTION
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15. ADVANTAGES DISADVANTAGES
• Simple
• Inexpensive
• No surgical risk
• One hyperthyroidism is controlled,
cure is permanent
• Nausea
• Loss of taste and taste change
• Swollen salivary gland
CHAPTER IV : MECHANISM OF ACTION
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16. THANK YOU !!
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