Antidiuretics

ANTI DIURETICS IN PHARMACOLOGY WHICH INCLUDES VASOPRESSIN AND ADH

1. ANTIDIURETICS 3 rd YEAR PHARM.D PHARMACOLOGY II

2. DEFINITION: An antidiuretic is a substance that helps to control fluid balance in our body by reducing urination, opposing diuresis. Antidiuretics reduce urine volume, particularly in diabetes insipidus, which is one of their main indications.

3. CLASSIFICATION: These agents are divided into three categories, Antidiuretic hormone and its analogues Natriuretics Miscellaneous

4. EXAMPLES ANTIDIURETIC HORMONE AND ITS ANALOGUES: Vasopressin Desmopressin Lypressin Terlipressin Oxytocin

5. NATRIURETICS: Thiazides Amiloride MISCELLANEOUS: Carbamazepine Chlorpropamide Indomethacin

6. M.O.A 1 ADH AND ITS ANALOGUES:

7. 2 NATRIURETICS: These drugs cause excretion of sodium alone in the urine but causes retention of water in the body. They inhibit NaCl co transporter in renal distal convoluted tubule. The antidiuretic action of thiazides is secondary to increased sodium excretion.

8. 3 MISCELLANEOUS: These agents induce the release of or enhance the action of Anti Diuretic Hormone, at least partially by reducing the production of prostaglandins in the kidney. These agents are useful as antidiuretics in diabetic patients.

9. PHARMACOLOGICAL ACTIONS: ADH and its analogues leads to vasoconstriction and cause an increase in arterial pressure. It promotes re absorption of water from renal tubular epithelium. Used to treat diabetes insipidus, increased thirst and urination.

10. ADH binds at V1 receptors and causes constriction of blood vessels and leads to raise in B.P. At V2 receptors it promotes endothelium dependent NO production and causes vasodilation. ADH on GIT – increased peristalsis, evacuation and expulsion of gases. ADH induces platelet aggregation and hepatic glycogenolysis.

11. Thiazides helps to prevent our body from absorbing too much salt, which can cause fluid retention. ADR for ADH and its analogues: Transient headache and flushing Nasal irritation, Congestion, Rhinitis Belching, Nausea, Vomiting Abdominal cramps, Pallor, Backache, Contraction of uterus in females.

12. ROLE OF THIAZIDES IN TREATING DIABETES INSIPIDUS:

13. CONTRAINDICATIONS FOR ADH AND ITS ANALOGUES: Ischemic heart disease Hypertension Chronic nephritis Psychogenic polydipsia