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Presentation on theme: "A ppt on THYROID HORMONESAND THYROID INHIBITORS By"— Presentation transcript:

Dr.Nanita Agrawal, Dr. Prashant ,MD dr prashant's

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I. THYROID HORMONE INTRODUCTION The thyroid hormone secretes 3 hormones: 1. Thyroxine (T4) 2. Tryiodothyronine (T3) 3. Calcitonin Former 2 are produced by thyroid follicles. Calcitonin produced by interfollicular ‘c’ cells. dr prashant's

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B. ACTIONS Growth and development: Essential for normal growth and development. Intermediary metabolism: Marked effect on lipid, carbohydrate and proteinmetabolism. Calorigenesis: Increase BMR. CVS: Heart rate, contractility and output are increased. GIT: Propulsive activity increased. dr prashant's

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Nervous system: Mental retardation is the hallmarkof cretinism. Skeletal muscle: Muscles flabby and weak in myxoedema. Kidney: Rate of urine flow is often increased. Haemopoiesis: Facilitatory to erythropoiesis. Reproduction: Indirect effect on reproduction. dr prashant's

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C. MECHANISM OF ACTIONS T3 (and T4) penetrate cells. Combine with a nuclear receptor. A specific DNA sequece called ‘thyroid hormone response element’ has been identified. T3-receptor complex binds. Derepression of gene transcription dr prashant's

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D. PREPRATIONS 1-thyroxin sod: Electroxin Roxin 100 ug tab. Thyranorm Thyrox 25 ug, 50 ug, 100 ug tabs. dr prashant's

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E. USES Cretinism: Due to failure of thyroid development. Detected during infancy or childhood. Mental retardation. Adult hypothyroidism: Develops as a consequence of thyroiditis, thyroidectomy, treatment with goiterogens; may accompany simple goiter if iodine. Myxoedema coma: Thyroid nodule: dr prashant's

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Nontoxic goiter: May be endemic or sporadic.deficient production of thyroid hormone leads to excess TSH-throid enlarges. Papillary carcinoma of thyroid: Empirical uses: Refractory anaemias Menstrual disorders, infertility not corrected by usual treatment. Chronic/ non healing ulcers Obstinate constipation dr prashant's

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2. THYROID INHIBITORS INTRODUCTION Drugs used to lower the functional capacity of the hyperactive thyroid gland. Throtoxicosis Two main causes are Grave’s disease and toxic nodular goiter dr prashant's

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B. CLASSIFICATION Inhibit hormone synthesis (Antithyroid drugs) propylthiouracil, methimazole, carbimazole. Inhibit iodide trapping (ionic inhibitors) thiocynates (-SCN) , perchlorates (-C1O4), nitrates (-NO3). Inhibit hormone release iodine, iodides of Na and K, organic iodide. Destroy thyroid tissue Radioactive iodine . dr prashant's

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3. ANTITHYROID DRUGS INTRODUCTION Inhibit iodination of tyrosine residues in thyroglobulin. Inhibit coupling of iodotyrosine residues to form T3 and T4. dr prashant's

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B. PHARMACOKINETICS Quickly absorbed orally Cross placenta Metabolised in liver Excreted in urine dr prashant's

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C. ADVERSE EFFECTS Hypothyroidism due to over treatment common but reversible. G.I. Intolerance, skin rashes and joint pain. Loss or graying of hair, loss of taste, fever and liver damage. Agranulocytosis dr prashant's

Propyltjiouracil : mg TDS followed by mg BD-TDS for maintenance PTU 50 mg tab. Methimazole: 5-10 mg TDS initially, maintenance dose 5-15 mg daily in 1-2 divided doses. Carbimazole: 5-15 mg TDS initially, maintenance dose mg daily in 1-2 divided doses, neo mercazole, thyrozole, antithyrox 5 mg tab. Carbimazole is more commonly used in india. dr prashant's

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E. USES The following strategies are adopted: Definitive therapy: Preferred in young patient with a short history. Preoperatively: Carbimazole before performing partial thyroidectomy. Along with 131 I. dr prashant's

No surgical risk Hypothyroidism, if induced, is reversible. Can be used even in children and young adults. dr prashant's

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G. DISADVANTAGES Prolonged treatment is needed. Not practicable in uncooperative/ unintelligent patient. Drug toxicity. dr prashant's

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4. IODINE AND IODIDES INTRODUCTION Inhibition of hormone release- ‘thyroid constipation’. B. PRERARATION AND DOSE Lugol’s solution Colloid iodine 10% Collosol dr prashant's

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C. USES Preoperative preparation Thyroid storm Prophylaxis of endemic goiter Expectorant Antiseptic dr prashant's

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D. ADVERSE EFFECTS Acute reactions: Swelling of lips. Eyelids, angioedema of larynx (may be dangerous), fever, joint pain. Chronic overdose (iodism): Long term use of high doses can cause hypothyroidism and goiter. dr prashant's

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5.RADIOACTIVE IODINE INTRODUCTION 131I: Physical half life 8 days- most commonly used. 123I: Physical half life 13 hours- only rarely used diagnostically. 125I: Physical half life 60 days. 131I emits x-rays as well as B particles. dr prashant's

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B particles utilized for their destructive effect on thyroid cells. 131I is concentrated by thyroid. Incorporated in colloid- emits radiation from within the follicles Thyroid follicular cellsundergo pyknosisand necrosis followed by fibrosis. dr prashant's

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Diagnostic u curie is given. Therapeutic Average therapeutic dose is 3-6 m curie. dr prashant's

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B. ADVANTAGES Treatment is simple, conveniently inexpensive. No surgical risk, scar or injury to parathyroids/ recurrent laryngeal nerves. Cure is permanent. dr prashant's

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C. DISADVANTAGES Hypothyroidism Long latent period of response. Contraindicated during pregnancy- cretinism. Not suitable for Young patients. dr prashant's

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6. B ADRENERGIC BLOCKERS Propranolol During thyrotoxic crisis. While awaiting response to carbimazole or 131I. Along with iodide for preoperative preparation before subtotal thyroidectomy. dr prashant's

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Our other websites dr prashant's

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