Pharmacology BMS 242

1. PharmacologyBMS 242 Dr. Aya M. Serry Lecture I Introduction; Scope of PharmacologyRoutes of Drug Administration 2014

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

4. 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

5. Nature of the Drug A Drugis 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

6. 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)

7. Definitions Pharmacodynamics Pharmacokinetics Pharmacotherapeutics Effect of the Drug on the Body What body does to the Drug Proper selection & use of the Drug to treat or prevent a disease

8. Routes of Drug Administration

9. Routes of Drug Administration 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 Drug’s route of administration is determined by: Major routes of drug administration include Enteral, Parenteral, and Topical routes

10. Routes of Drug Administration • Drug dosage form is swallowed by mouth allowing oral absorption through GIT (Oral) • Drug dosage form may be placed topically (Not swallowed), facilitating direct and rapid absorption into the blood stream. this includes: • Under the tongue (Sublingual) Enternal Route: Administering a drug through the Intestine • Between the gums and inner cheeks lining (Buccal) • Given by suppository or enema (rectal)

11. 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 Advantages of the Oral Route:

12. 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:

13. Oral Route First Pass Effect Disadvantages of the Oral Route: • Most of drugs absorbed from GIT enter the portal (liver) circulation before they are distributed to the systemic (general) circulation • Some of the drugs 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. Or change the route of drug’s administration

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

15. Rectal Route • 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 Advantages: Disadvantages: • Drugs may irritate the rectal mucosa • Not a well-accepted route ( low patient compliance)