Tiêu đề 27. DIAGNOSTIC AGENTS.pdf ✅

PHARMD GURU Page 1 INTRODUCTION:  Diagnostic agents are chemical substances used to detect abnormalities in tissues and organs or to test organ function.  They do not have medicinal or pharmacological effects.  X-ray films are commonly used for radiography. TECHNIQUES & DIAGNOSIS: TECHNIQUE USED FOR Angiography Blood vessels Arthrography Joints Bronchography Lungs Cholangiography Gall bladder and bile duct Hepatography Liver Lymphography Lymph nodes & vessels Myelography Brain & spinal cord Pyelography Kidney and ureter Splenohepatography Liver & spleen Urography Urinary tract CLASSIFICATION OF DIAGNOSTIC AGENTS: 1. Drugs used to test organ functions 2. Drugs used to determine blood volume and haemopoietic function 3. Drugs used as X-ray contrast media 4. Drugs used for miscellaneous diagnostic purposes DIAGNOSTIC AGENTS USED TO TEST ORGAN FUNCTIONS:  For Kidney Function: p-Amino hippuric acid, Inulin, Phenosulphophthalein  For Liver Function: Rose Bengal, Sulphobromophthalein sodium  For Gastric Function: Histamine phosphate, Pentagastrin, Xylose  For Cardiac Function: Evans blue dye  For Pancreatic Function: Bentiromide DIAGNOSTIC AGENTS
PHARMD GURU Page 2 DRUGS USED TO DETERMINE BLOOD VOLUME:  Evans blue – Used for determining blood (or plasma) volume. DIAGNOSTIC AGENTS USED FOR IMPORTANT STUDIES: AGENT USED FOR Fluorescein sodium Ophthalmological studies Phentolamine Pheochromocytoma diagnosis Dexamethasone Endocrine gland dysfunction assessment Edrophonium Tensilon test (evaluation of Myasthenia Gravis) Methacholine Methacholine challenge test (lung airway constriction) L-Arginine Growth hormone secretion test Isosulfan blue Lymphatic system imaging Benzyl penicilloyl polylysine Drug hypersensitivity testing RADIOPHARMACEUTICALS AS DIAGNOSTIC AGENTS: 1) Radioactive compounds used for diagnostic and therapeutic purposes. 2) Administered through various routes (oral, injection, eye drops, bladder instillation) in small amounts. 3) Dosage varies depending on the type of test. 4) Administered under the supervision of a specialist doctor. 5) Units of measurement: Curie, Becquerels. EXAMPLES OF RADIOPHARMACEUTICALS (FOR DIAGNOSTIC PURPOSE):  Biliary Tract Blockage – Tc99m Disofenin  Blood Volume Studies – Sodium Chromate Cr51  Blood Vessel Disease – Sodium Pertechnetate Tc99 m  Bone Diseases – Sodium Fluoride F18  Bone Marrow Disease – Chromium Cr51, Tc99 m Sulfur Colloid  Brain Diseases & Tumors – Indium In111  Cancer Tumors – Gallium Citrate Ga67, Sodium Fluoride F18  Heart Disease – Ammonia N13, Rubidium Rb82, Thallium Chloride Tl201  Kidney Disease – Iodohippurate Sodium I125, Tc99m  Liver Disease – Ammonia N13, Tc99m Albumin Colloid  Lung Disease – Krypton Kr81m, Xenon Xe133
PHARMD GURU Page 3 RADIOLOGICAL CONTRAST MEDIA: DEFINITION:  Any substance that, when administered to a patient, enhances the visualization of an organ or tissue is called a contrast media.  It has the property of opacifying X-ray radiations.  Can be either inorganic or organic. CLASSIFICATION OF CONTRAST MEDIA: 1) Positive Contrast Media – Absorbs X-rays (Radiopaque agents)  Subcategories: o Heavy Metals & Their Salts (Inorganic) o Iodized Oils o Iodinated Organic Compounds (Organic)  Water-Soluble Contrast Media  Water-Insoluble Contrast Media 2) Negative Contrast Media – Transparent to X-rays  Renders tissue structures more translucent  Examples: Air, Oxygen, Nitrogen 1) POSITIVE CONTRAST MEDIA: HEAVY METALS AND THEIR SALTS:  Have a high atomic number and are radiopaque (e.g., Barium Sulphate - BaSO4).  Properties: o Low systemic toxicity o Low water solubility o Lack of osmotic activity  Uses: o Used for Gastrointestinal Tract (GIT) examinations o Administered as a suspension or thick cream, either orally or rectally  Additives: o Sodium citrate stabilizes the preparation o Sorbitol enhances function
PHARMD GURU Page 4 METALLIC SALTS:  Tantalum oxide – Used for Bronchography & Esophagography.  Calcium tungstate & Barium titanate – Used for stomach, small intestine, and esophagus imaging.  Ferrites (Fe2O3): o About 80% opacity compared to BaSO4. o Contains Zn, Cu, Mn, Ni, and Mg. o Used for bronchi, stomach, and small intestine studies. IODIZED OILS:  Preparation: o Obtained by iodination of vegetable oils with hydroiodic acid.  Properties: o Iodinated fatty acid derivatives (Yellow to amber-colored). o Decomposes upon exposure to light and air. o Releases inorganic iodine in the body, which appears in urine.  Uses: o Hepatography (Liver imaging). o Lymphography (Lymphatic system imaging). o Hepatospleenography (Liver and spleen imaging). ORGANIC IODINE COMPOUNDS:  Most widely used contrast agents.  First Agent Used: Tetraiodophenolphthalein.  Importance: The amount of iodine determines opacity. SUB-CLASSIFICATION: 1. Water-Soluble Contrast Media o Contains pharmaceutical buffers (phosphate/citrate) & sequestering agents. o Mainly used for:  Urography (Kidney and ureter imaging).  Angiography (Arterial system imaging).