Introduction to Pharmacology Lecture 1 - PDF
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The British University in Egypt
Dr. Nesreen Elgayar
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Summary
Lecture notes covering Introduction to Pharmacology, with a focus on pharmacokinetics and the factors affecting drug absorption. The lecture touches on drug properties, formulations, and clinical significance. It is from the British University in Egypt.
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Introduction to Pharmacology Pharmacokinetic 1 Dr. Nesreen Elgayar Pharmacodynamic Body Drug Pharmacokinetic Outlines Introduction about Pharmacology. Pharmacokinetics. Absorption of Drug. Factors Affecting Absorption...
Introduction to Pharmacology Pharmacokinetic 1 Dr. Nesreen Elgayar Pharmacodynamic Body Drug Pharmacokinetic Outlines Introduction about Pharmacology. Pharmacokinetics. Absorption of Drug. Factors Affecting Absorption of Drug. Drug Properties. Drug Formulation. Pharmacokinetics Pharmacokinetics It is a quantitative study of drug Absorption Distribution ADME Metabolism Excretion Absorption Absorption is the passage of a drug from site of administration to reach Blood Factors affecting Drug Absorption ? I- Drug Factors Drug properties Drug Formulation II- Patient Factors I. Drug properties MW ↓ MW → ↑ Absorption ↑ MW → ↓ Absorption e.g. procaine penicillin (PP) Lipophilicity Solubility Non-ionized drug is lipid-soluble and diffusible. Ionized drug is water-soluble and non-diffusible..Ionization is pH-dependent Solubility In solution, Drugs are ionized to different degrees depending on : -pH of the solution (Body fluid) and -pKa of the drug. pKa (Dissociation or Ionization Constant) It is the pH of the medium at which drug (PH=PKa) 50% 50% Ionized Nonionized Acidic Drug Basic Drug Acidic Basic Ionization Hydrophilic Nonionized Execreted Nonionized Lipid soluble( )Absorped )Lipid soluble( Absorped Clinical Significance of pKa 1. GIT Aspirin: (weak acid; pKa 3.5) is non-ionized in stomach → crosses cell membrane → gastric mucosal cells → trapped inside these cells (aspirin trap) → death of cells → peptic ulceration Clinical Significance of pKa 2. Kidney Drug ionization →↑ renal excretion. So…. Alkalinization of urine in Acidic drug Toxicity e.g. Aspirin Acidification of urine in Basic drug Toxicity e.g. Amphetamine II. Drug Formulation Active Drug + Vehicle Vehicle: Aqueous (cream) > absorbable Oily (ointment) Tablet Disintegration Particles Dissolution Molecules + Ions Fragments Absorbed.Slow release tab. & sustained release cap (Spansules) Long Acting Less Frequent administration Less Adverse Effects (Low Good Compliance peak Level) How to prolong Action of Drug? ↑ MW Use Oily Prep. Use Spansules Add VC to local anesthesia
