1z Intro to Pharma

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Pharmacology
Third Year

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1z Intro to Pharma

  1. 1. Introduction DR. Heba A Mahmoud
  2. 2. Dental Pharmacology Credit Hours : 2 Cr . hr Duration : One semester Course format: 2 lectures/week: Thursday : :2-411-9
  3. 3. Course Evaluation Evaluation (Total 10 0 marks): 1. Continuous Assessment: 5 0 Marks • Three Written Quizzes, including short answer questions. ( select the Best 2 Quizzes). • No Make –up Exams 2. Final Written Examination: 5 0 Marks Including MCQs.
  4. 4. Recommended Books Pharmacology & dental therapeutics by Robin A Seymour, John G Meechan and Michael S Yates (Latest edition). Basic & Clinical Pharmacology by Katzung (Latest edition).
  5. 5. Pharmacology Pharmacology is : the study of drugs. This include their origin, chemical structure, preparation, administration, actions, metabolism and excretion. What is a drug? Drug is a substance used to: Cure ,Control , Prevent or Diagnose disease
  6. 6. Definitions Pharmacokinetics: study of the absorption, distribution, biotransformation (metabolism) and excretion of drugs (ADME). Pharmacodynamics: study of biochemical and physiological effects of drugs and study of mechanisms of drug action in living organisms. Pharmacotherapeutics (clinical pharmacology): study the use of drugs to prevent and treat diseases. Toxicology: the study of poisons, including the adverse effects of drugs on living organisms.
  7. 7. Naming of drugs Three names
  8. 8. SOURCES OF DRUGS NATURAL SOURCES:  Plant source: Digoxin, atropine and morphine  Animal source: Insulin  Microorganisms: Penicillin  Mineral source: Ferrous sulphate SYNTHETIC SOURCE: Aspirin GENETIC ENGINEERING (DNA-Recombinant technology.) Human insulin
  9. 9. Dosage forms of drugs
  10. 10. 1. Solid dosage forms TabletEffervescent tabletsPowder Lozenges Sublingual pelletCapsules (soft gelatin)Capsules (hard gelatin)Rectal suppository
  11. 11. 2. Liquid dosage forms Solution Suspension Enema.
  12. 12. Liquid dosage forms (cont.)
  13. 13. 3. Topical dosage forms They are applied on the surface of skin or mucous membranes •Ointments (semisolid), paints, lotions, cream (semisolid), gel, eye drops and nasal drops •Implants Drugs administered in small flexible capsule. These capsules are surgically implanted subdermally. Transdermal patch
  14. 14. 4. Buccal dosage forms Sublingual pellet Lozenges Mouth paint Mouth gargle Buccal spray
  15. 15. Enteral administration involves the esophagus, stomach, and small and large intestines (i.e., the gastrointestinal tract). Parenteral = para beside= Beside enteral
  16. 16. 1.ORAL ROUTE The most common and acceptable route. Drug is administered as tablets, capsules, syrup, sustained release tablet. 3. RECTAL ROUTE Suppositories or enema. ENTERAL ROUTES 2. SUBLINGUAL ROUTE
  17. 17. Parenteral ROUTE 1. Intradermal: (e.g. vaccination) 2. Subcutaneous injection (S.C.) 3. Intramuscular (I.M.) injection: the drug is injected into skeletal muscle Advantages •Technically easier than I.V. •No first pass metabolism and no food drug interaction •Oily solution can be given •A long term effect from a single dose can be achieved
  18. 18. 4. Intravenous (I.V.) Either slow bolus injection or infusion method. Advantages: •100% bioavailability. •The drug gets to the site of action more quickly which required in emergency. •Used when the alimentary route is not feasible (e.g., when the patient is unconscious, or poor oral absorption). •The dose can often be more accurately delivered. •Large volumes can be delivered intravenously. •Useful for irritant drug.
  19. 19. MISCELLANEOUS ROUTES 1) Topical administration: Drugs can be applied to various mucous membranes and skin. 2) Inhalation: it is the common route of administration for gaseous and volatile drugs. -Drugs are given by inhalation are gases (gaseous general anesthesia) or solution in the form of aerosol (by nebulizer or atomizer) -Provide a rapid access to systemic circulation. -Used to apply drugs directly to the lungs e.g. bronchodilator in asthma. Advantages:  Quick onset of action  Dose required is less so systemic toxicity is minimized.  Amount of drug can be regulated. Disadvantage:  Local irritation may cause increased respiratory secretions and bronchospasm 4 )Transdermal delivery system: by application of drugs to the skin for systemic effect. 5) Intranasal : as nasal spray.
  20. 20. PHARMACOKINETICS What body does to drug?
  21. 21. ADME 1. Absorption of drugs Movement of a drug from its site of administration into the blood stream. Factors affecting drug absorption Degree of ionization Degree of solubility Degree of stability Dose Dosage form First pass metabolism
  22. 22. Bioavailability Percentage (%) of administered dose that reaches systemic circulation Bioavailability is 100% after IV variables after oral administration Factors that can alter bioavailability Dosage form (e.g. tablet, capsule), Route of administration, Stability of the active ingredient in the gastrointestinal tract, and Extent of drug metabolism before reaching the systemic circulation First pass metabolism Metabolism of some drugs in single passage through (gut, liver, lung) before reaching systemic circulation
  23. 23. ADME 2. Drug Distribution process by which a drug leaves the blood stream and enters the extra vascular tissues Factors controlling distribution: Blood flow to the organ Binding of drugs to plasma proteins Barriers to drug distribution Capillary permeability Physical and chemical characteristics of drug
  24. 24. Drugs in the plasma may exist in the free form or may be bound to plasma proteins. General features of plasma protein binding -The extent of plasma protein binding is highly variable and ranges from virtually 0% to greater than 99%-bound. -Only the free (unbound) drug diffuses through capillary walls and produce action. Consequences of plasma protein binding: A. Plasma protein binding decreases distribution, metabolism and renal excretionof drug B. Drug interactions can be produced by plasma protein binding if several drugs compete for binding sites on protein molecules. Plasma protein binding
  25. 25. ADME Drug Metabolism Definition: chemical alteration of drugs in the body. Aim: It’s an important mechanism to terminate action of some drugs
  26. 26. Sites of drug metabolism 1-Organs: liver (main site), Lung, kidney, GIT, Plasma, .
  27. 27. Factors affecting drug metabolism  Hepatic Microsomal enzyme( presence of enzyme inducers or enzyme inhibitors )  Genetics.  Age  Gender  Diet  Disease  Route of administration  Dosage     Hepatic Microsomal enzyme( presence of enzyme inducers or enzyme inhibitors )  Genetics.  Age  Gender  Diet  Disease  Route of administration  Dosage   
  28. 28. Hepatic Microsomal enzyme  Hepatic Microsomal enzyme Inducers: They increase Metabolism of drugs leading to decrease their action. Examples: Phenobarbitone, Phenytoin, Tobacco Smoking, Ethyl Alcohol  Hepatic Microsomal enzyme Inhibitors:  They decrease Metabolism of drugs leading to increase their action. Examples: Oestrogens, Progesterone, Cimetidine
  29. 29. ADME Drug Elimination Definition: Removal of drug from the body. Routes of elimination: Drug metabolism Elimination via kidney and other routes
  30. 30. ADME Drug Elimination Renal (main organ for drug excretion) GIT Sweat Lungs Milk Nose. Organs involved in drug excretion
  31. 31. Factors affecting renal excretion 1- Glomerular filtration rate. 2- Change in urinary pH: • Alkalinization of urine (by NaHCO3 ) leading to increase excretion of acid drugs e.g. aspirin, barbiturates. • Acidification of urine (by NH4 CL or vit. C) leading to increase excretion of base drugs e.g. ephedrine, morphine.

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