Introduction; Scope of Pharmacology Routes of Drug Administration Pharmacology I BMS 242 Lecture I Introduction; Scope of Pharmacology Routes of Drug Administration Dr. Aya M. Serry 2016

10 20 40 100 SUBJECT GRADE Quizzes First Assessment Exam Second Assessment Exam Self Learning (Project) Final Exam 40 TOTAL 100

Course Objectives Upon Completion of this course you should be able to: Recognize the different routes of drug administration and the advantages and disadvantages of each one   Recognize the fundamental principles of pharmacodynamics (i.e. drugreceptor interactions) and pharmacokinetics (i.e. absorption, distribution, metabolism, and elimination of drugs). Identify how drugs alter cellular function through the study of pharmacodynamics. Determine how the body handles drugs through pharmacokinetic processes such as absorption, distribution, metabolism, elimination, dose-response relationships, half-life, steady-state concentrations and volume of distribution. Describe the pharmacology of the autonomic nervous system at an introductory level as preparation for understanding CNS drug actions. Describe the distribution and identify the function of clinically relevant receptors in the autonomic nervous system and identify why they represent useful targets for therapeutic manipulation. List and discuss selected drugs used to stimulate or inhibit the sympathetic or parasympathetic nervous systems, including their clinical uses and potential adverse effects. Name major classes and provide specific examples, mechanisms of action, adverse effects and contraindications for drugs affecting the autonomic nervous system and central nervous system. Explain the indications, mechanism of action, adverse effects, contraindications and potential drug interactions of Aspirin, NSAIDs and Acetaminophen Explain the mechanism of action of CNS depressants (Anxiolytics) and CNS stimulants and their clinical uses

Lecture Objectives Understand what’s Pharmacology Identify the difference between Pharmacokienetics and Pharmacodynamics Define what’s a Drug and its nature Differentiate between different routes of drug administration and their advantages vs. their disadvantages

Different routes of Administration From different Sources Introduction Different routes of Administration ? Drug Living System Effect From different Sources Treatment Prevention Diagnosis Pharmacology: The science that studies the effects of the drug on living systems and How? the drug produces these effects

Introduction Drug Effects of the Drug How the Drug acts Therapeutic effects Adverse effects Factors affecting Drug effects Mechanism of action Therapeutic Indications Contra-Indications Drug Interactions Pharmacokinetics

Definitions Pharmacodynamics Pharmacokinetics Pharmacotherapeutics Effect of the Drug on the Body Effects of the body on the drug Proper selection & use of the Drug to treat or prevent a disease

Nature of the Drug A Drug is any substance (other than nutrients and essential dietary ingredients) which when administered to a living organism, produces a biological effect Drug Synthesized within the Body Not synthesized within the Body (Xenobiotics) Synthetic Hormones Enzymes Neurotransmitters Obtained from Natural Products (Plants or Animals) Obtained through Genetic Engineering

Mechanisms of Drug Action How Does a Drug Acts? Interaction with Protein Targets Chemical Physical (Drug Targets) Neutralization Chelation Adsorbtion Osmosis Receptor Ion Channel Enzyme Transporter (Carrier)

Routes of Drug Administration Drug’s route of administration is determined by: Major routes of drug administration include Enteral, Parenteral, and Topical routes Properties of The drug ( e.g.: Water and lipid Solubility , Ionization…etc.) Therapeutic Objectives Rapid onset of action Need for long term treatment Restriction of delivery to a specific site

Routes of Drug Administration

Routes of Drug Administration Enteral Route: Administering a drug by mouth Drug dosage form is swallowed allowing oral absorption through GIT (Oral) Drug dosage form may be placed topically, facilitating direct and rapid absorption into the blood stream. this includes: Under the tongue (Sublingual) Between the gums and inner cheeks lining (Buccal) given by suppository or enema (rectal)

Advantages of the Oral Route: Simplest and most common route of administration Can be self administered Overdose easily overcome with antidote (e.g.: Charcoal) Cheap (compared to most parental routes) Large surface area for absorption Pain free, Convenient to patients

Oral Route Disadvantages of the Oral Route: Drug is Subjected to First Pass Metabolism (First Pass Effect) Gastric acidity may limit absorption Drug can be irritating to GIT Drug-Drug interaction (e.g: sedatives with antihistaminic) and Drug-Food interaction (e.g: Ciprofloxacin with dairy products) influencing drug activity Effect is too slow for emergency Can’t be given to unconscious patients

Disadvantages of the Oral Route: First Pass Effect Most of drugs absorbed from GIT enter the portal (liver) circulation before they are distributed to the systemic (general) circulation The drug will be metabolized in the liver before reaching the target organ, decreasing drug efficacy. E.g.: Nitroglycerin is 90% cleared during a single passage through the liver (that’s why nitroglycerin in not administered orally) Thus the dose of a drug that has high first pass effect should be increased to ensure that enough dose reaches the target organ

Sublingual & Buccal Routes Advantages: Avoiding First Pass Metabolism Avoiding destruction of the drug by GI acidity Rapid Absorption through capillary network directly into systemic circulation Disadvantages: Small dose limit Bad taste of drug Irritation of oral mucosa

Rectal Route Advantages: Disadvantages: Partially by-passes first-pass effect (50 %) Bypasses destruction by stomach acid Ideal if drug causes vomiting Ideal in patients who are vomiting, or unconscious patients Disadvantages: Drugs may irritate the rectal mucosa Not a well-accepted route ( low patient compliance)

Conclusion Pharmacology is the science that studies the effects of the drug on living systems and how the drug produces these effects A Drug is any substance (other than nutrients and essential dietary ingredients) which when administered to a living organism, produces a biological effect and it can be either natural or synthetic in nature The major routes of drug administration include Enteral, Parenteral and Topical routes; each route has its advantage over the other one depending on the properties of the drug used and the therapeutic objectives needed