Final course module for may 2010 pharmacology-iii - copy - copy
Thyroid hormone
1.
2. T 4 & T 3 – Iodine containing derivatives of thyronine T 4 -thyroxine ( 3,5,3ˈ,5ˈ -tetraiodothyronine) T 3 -triiodothyronine (3,5,3ˈ triiodothyronine) SYNTHESIS Thyroglobulin molecule-glycoprotein synthesized by thyroid cells MW-660 KDa.
3.
4.
5.
6. Relation between T 4 and T 3 Thyroid secrets more T 4 than T 3 T 4 is major circulating hormone T 3 is 5 times more potent than T 4 and acts faster. T 3 is more avidly bound to the nuclear receptor than T 4 . About 1/3 of T 4 is converted to T 3 in peripheral tissues. On the basis of this ,it is believed that T 3 is the active hormone & T 4 is only the transport form.
7.
8.
9.
10.
11. Inhibits thyroid hormone release- Lithium Inhibit peripheral conversion of T4 to T3- Amiodarone Inhibit thyroglobulin iodination and coupling reaction- Sulphonamides Paraaminosalicylic acid Induce metabolic degradation of T4/T3- Phenobarbitone Phenytoin Carbamazepine Rifampin
