Absorption of Drugs NURS 1060 Exam 1 PDF

Absorption of 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  Clinical Decision...

Absorption of 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  Clinical Decision 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.  Explain the concept of the pH of the surrounding medium and drug preparation as weak acids or weak bases Unit Outcomes  Discuss factors affecting drug absorption.  Contrast enteral and parenteral routes of administration.  Discussthe effects of the blood-brain barrier on drug absorption Just A Note:  These concepts 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 Absorption the site of administration into the blood movement of the drug from Distribution the blood to the site of action or storage area Four Basic Processes of Pharmacokinetics in Sequence Metabolism enzymatic breakdown of 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 drug Absorption 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) Before Absorption of an orally administered drug  Whatneeds to happen before a drug can be absorbed in the GI track?  Disintegration - Tablet begins to break apart  Dissolution – Powder mixes with stomach fluid into a solution or liquid  Then, how does absorption happen?  With most drugs --- Passive Diffusion How Does Absorption Happen? Passive Diffusion  Drugconcentration moves from area of higher drug concentration to area of lower drug concentration  Mechanism of passage across membranes used by most drugs Molecules move from area of high concentration  area of low concentration What type of molecule can cross a lipid membrane? Water Soluble Lipid Soluble The pH of the drug and the pH of the environment an impact if a drug is water-soluble or lipid-soluble   Acid giving up a proton or base accepting a proton causes the acid or base to become a charged Ionization particle or ION.  This is a reversable bond. Ions  Acidis a proton donor  tends to ionize in basic (alkaline) media  Base is 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 Some 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 Which route usually absorbs the fastest?  Intramuscular  Intravenous  Oral  Subcutaneous  Oral (GI) IM (in muscle) IV (in vein) SLOWEST MEDIUM FASTEST Examples of Absorption Rate Ask or Vote  Afterstudying this week, what course concepts are confusing to you?  pollev.com/eginsbur g150 Passage of Drugs Across Cell Membranes Directly Transport diffusing Channels and systems (P- across the pores glycoprotein) membrane   Mostcommon method used by drug developers  To directly cross the cell Direct diffusing membrane, a drug must across the be lipid soluble. Membrane  Cell membranes are (Passive primarily lipids A drug must be able to Diffusion) cross the lipid membrane to enter the cell   Very few drugs cross membranes via Channels and channels or pores  Channels are extremely small Pores  Used by potassium and sodium   Transport systems are carriers that move drugs across the cell Transport membrane Systems and  P-glycoprotein is a P-glycoprotein transporter protein  Transports drugs out of cells  “anti-absorption” 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 drugs out of the intestine, 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,  Pharmacokinetics True/False  When the poll is active respond at:  pollev.com/eginsburg150 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 Absorption Activity  Document is on Blackboard  Break in Small Groups  Discuss and complete pages 5 and 6  Answers will be posted on Blackboard soon  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. Review of Absorption  Movement of a drug from its site of administration into the blood  Rateof 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 compressed powders Pharmaceutical Enteric-coated Preparations covered with material that dissolves in for the intestine Oral Sustained-release Administration capsule filled with tiny spheres of 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 How do you think food impacts absorption?  Changes in pH  Digestive enzymes can inactivate  Example: Insulin (can never be given enterally)  Heavy metals (calcium, antacids) can bind and cause medication to be insoluble and inactive  Example: Tetracycline Exam 1 Review  When the poll is active respond at:  pollev.com/eginsburg150 Review of Pharmacokinetic Process movement of the drug from the site of Absorption administration into the blood movement of the drug from the blood Distribution to the site of action or storage area enzymatic breakdown of a drug into a Metabolism metabolite removal of the drug or metabolite from Excretion the body  Reminder: Information from Absorption Study Guide and Textbooks are necessary NURS 1060: to acquire Basic Pharmacology concepts Exam 1 Preparation Question Format: Multiple Choice or Select All That Apply to Encourage SUCCESS! Includes in class activities Occurs in Week 4 All Readings Any other Assignments