1060W2-3.AbsorptionNC.pptx

Absorption of Oral Drugs NURS 1060: Exam 1 OUTCOME  Discusscritical thinking and clinical reasoning to provide quality patient care COMPETENCY  Discuss critical thinking and clinical judgment used to provide accurate and safe medication administration CONCEPT...

Absorption of Oral Drugs NURS 1060: Exam 1 OUTCOME  Discusscritical thinking and clinical reasoning to provide quality patient care COMPETENCY  Discuss critical thinking and clinical judgment used to provide accurate and safe medication administration CONCEPT  ClinicalDecision Making: A process used to examine and determine the best actions to meet desired goals; requires anticipating, recognizing and organizing patient problems to respond with urgency and/or importance in a preferential order to avoid or minimize adverse changes in a patient’s condition.  Acid-Base Balance: The physiological mechanisms that maintain blood pH critical to homeostasis and optimal cell function. Unit Outcomes  Explain absorption following oral drug administration  Identify the basic pharmacokinetic processes.  Define the basic pharmacokinetic processes.  Explain the passage of drugs across membranes.  Discuss P-Glycoprotein role as a transporter.  Explainthe concept of the pH of the surrounding medium and drug preparation as weak acids or weak bases Unit Outcomes  Discuss factors affecting drug absorption.  Contrastenteral and parenteral routes of administration.  Discussthe effects of the blood-brain barrier on drug absorption Just A Note:  Theseconcepts contain some difficult material.  These concepts lay an important foundation for the rest of the course. Pharmacokinetics The study of drug movement throughout the body.  movement of the drug from the site of Absorption administration into the blood movement of the drug from the blood to the Distribution site of action or storage Four Basic Processes area of Pharmacokinetic enzymatic breakdown of s in Sequence Metabolism a drug into a metabolite removal of the drug or Excretion metabolite from the body Fig. 4-1. DRUGS ADMINISTERED ORALLY The four basic pharmacokinetic processes. Dotted lines represent membranes that must be crossed as drugs move throughout the body.  movement of a Absorption drug from the site of administration into the blood Routes of Drug Administration Enteral Parenteral Absorbed in the IV, IM, SubQ GI track Other Routes PO, sublingual, (Transdermal, buccal, rectal Inhalation, Conjunctival, etc) Passive Diffusion  Mechanism of passage across membranes used by most drugs (how the drug gets into the blood)  Drugconcentration moves from area of higher drug concentration to area of lower drug concentration Molecules move from area of high concentration  area of low concentration Absorption of an orally administered drug  Absorption depends on:  Disintegration - Tablet begins to break apart  Dissolution – Powder mixes with stomach fluid into a solution or liquid  Then, passive diffusion of the drug can occur   Acidgiving up a proton or base accepting a proton causes the Ionization acid or base to become a charged particle or ION. Ions  Acid is a proton donor  tends to ionize in basic (alkaline) media  Baseis a proton acceptor  tends to ionize in acidic media Acid–Base Applied to Absorption Acid drug in the acid Base drug in the base environment of the environment of the stomach intestine Non ionized = lipid soluble Non ionized = lipid soluble Readily diffuse across the Readily diffuse across the membrane membrane Acid–Base Applied to Absorption Basic drug in the acid Acid drug in the base environment of the environment of the stomach intestine Ionized = water soluble Ionized = water soluble Unable to penetrate lipid Unable to penetrate lipid membrane membrane Factors that Affect Absorption Rate of dissolution Based on individual drug Surface area Intestine has more surface area due to villi and larger area than stomach Blood flow Most rapidly absorbed drugs are in the body at high blood flow areas  Oral (GI) IM (in IV (in vein) SLOWEST muscle) MEDIUM FASTEST Examples of Absorption Rate Passage of Drugs Across Cell Membranes Directly Transport Channels and diffusing systems (P- pores across the glycoprotein) membrane   Veryfew drugs cross membranes via channels or Channels ports and Pores  Channels are extremely small  Used by potassium and sodium   Transport systems are carriers that move drugs across the cell Transport membrane Systems  P-glycoproteinis a P- transporter protein glycoprotein  Transports drugs out of cells. Transport Systems P-glycoprotein Transporting drugs out of cells In the transports drugs out of liver cells into the bile for elimination liver, In the transports drugs out of the blood into the urine kidney, In the transports drugs across the membranes that separate the lumen of the intestine from the blood –transports intestine drugs out of the blood and into the intestine. , In the transports drugs out of the brain and back into the blood to decrease drug access to the brain. brain,   Mostcommon method used by drug developers  To directly cross the cell membrane, a drug must Direct be lipid soluble. diffusing  Cell membranes are primarily lipids across the A drug must be able to Membrane dissolve into the lipid membrane to enter the cell.  Direct diffusing across the cell membrane Fig. 4-2. Structure of the cell membrane. The cell membrane consists primarily of a double layer of phospholipid molecules. The large globular structures represent protein molecules imbedded in the lipid bilayer. Review Acid-Base Ionization Acid in basic drugs ionize … environments Base in acid drugs ionize … environments Ion Trapping (pH partitioning)  When the pH of the fluid on one side of a membrane differs from the pH of the fluid on the other side, drug molecules accumulate on the side where the drug is in the ionized state  Acid drugs accumulate on the base side.  Basic drugs accumulate on the acid side Ion Trapping (pH partitioning) Example: Stomach fluid pH = 1 (acidic) Plasma(blood) pH = 7.4 (basic or alkaline) Aspirin is an acid drug. When aspirin is in the stomach…  Is aspirin ionized?  No, not ionized -Acid drug in acid environment  Non ionized = lipid soluble  Readily diffuse across the cell membrane into blood stream  The aspirin seeks to ionize so it accumulates or collects in the blood and can then go to the site of action in the cells. Ion Trapping (pH partitioning)  pH intestine = 6-7 = basic  Plasma/blood pH = 7.4 = basic or alkaline  7.35-7.45 `Absorption of an Acidic Pill Taken PO Mouth---Esophagus--Stomach Acidic stomach, Acidic Pill - dissolves Non-ionized(lipid soluble) Exits stomach using passive diffusion Drug crosses over membrane due to stomach pH of 1 going to vascular pH of 7.4 `Absorption of a Basic Pill Taken PO Mouth---Esophagus---Stomach Acidic stomach, Basic Pill - dissolves Ionized (water-soluble) remains in stomach and travels to intestine Intestine (basic) and basic pill Exit intestines using passive diffusion  Tight junctions between the cells that compose the walls of most capillaries in the CNS Blood-Brain Drugs must be able to pass through cells of the capillary Barrier wall. Only drugs that are lipid- soluble can cross the BBB. Absorption  Movement of a drug from its site of administration into the blood  Rate of absorption determines how soon effects will begin.  Amount of absorption helps determine how intense the effects will be. GI Absorption into Vascular System *(except oral mucosa and Drug is absorbed from the GI tract* into the bloodstream rectum because of direct vascular absorption) Blood moves the drug into the portal vein and must PASS through the liver Then, the drug goes into the Inferior Vena Cava on its way to the heart From the heart, the drug is pumped into general circulation. Movement of drugs GI absorption. Oral drugs absorbed from the GI tract— stomach and intestine  Tablets Pharmaceutic compressed powders al Enteric-coated Preparations covered with material that dissolves for in the intestine Oral Sustained-release Administratio capsule filled with tiny spheres of n different colors: each color contains drug that dissolve at different times thought the day. Additional Routes of Administration will be discussed in NURS 1090  Topical  Transdermal  Inhaled  Rectal  Vaginal  IV, IM, Sub q Which route absorbs the fastest?  Intramuscular  Intravenous  Oral  Subcutaneous Review of Pharmacokinetic Process movement of the drug from the site Absorption of administration into the blood Distributio movement of the drug from the blood to the site of action or n storage area Metabolis enzymatic breakdown of a drug into m a metabolite removal of the drug or metabolite Excretion from the body  Reminder: Information from Absorption Study Guide and Textbooks NURS 1060: are necessary to acquire Basic Pharmacology concepts Exam 1 Preparation Question Format: Multiple Choice or Select All That Apply to Encourage Includes in class SUCCESS! Occurs in Week 4 activities All Readings Any other Assignments