Intro to pharmacology


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Intro to pharmacology

  1. 1. Introduction to Pharmacology By Prof. Dr. Shah Murad [email_address]
  2. 2. <ul><li>Pharmacology deals with all aspects of drug/medicine/chemical compounds,including their source,effects,side effects,permeability,distribution,metabolism,mode of action, elimination/excretion in the body. </li></ul>
  3. 3. Drug/Medicine <ul><li>Chemical compound used for prevention, diagnosis and cure of diseases </li></ul>
  4. 4. <ul><li>Therapeutics term is used often for cure of disease by drugs </li></ul><ul><li>Therapeutic’s alternate term is used “chemotherapy” but it is commonly applied to cytotoxic/anti-tumor drugs </li></ul>
  5. 5. General terms used in Pharmacology <ul><li>Pharmacokinetics </li></ul><ul><li>Pharmacodynamics </li></ul><ul><li>Pharmacotherapeutics </li></ul><ul><li>Toxicology </li></ul><ul><li>Pharmacy </li></ul><ul><li>Posology </li></ul><ul><li>Pharmaceutics </li></ul><ul><li>Pharmacognosy </li></ul><ul><li>Pharmacogenetics </li></ul>
  6. 6. Drug nomenclature <ul><li>Chemical name </li></ul><ul><li>Non-proprietary name (0fficial name) </li></ul><ul><li>Proprietary(Brand) name </li></ul>
  7. 7. Essential drug concept <ul><li>W.H.O has defined essential drugs as “those chemical compounds that satisfy priority health care needs of the population” </li></ul>
  8. 8. Orphan drug <ul><li>Biological products for diagnosis,treatment,prevention of a rare disease or condition for which there is no reasonable expectation that the cost of developing and marketing it will be recovered from the sales of that drug,e.g. sodium nitrate,potassium sulfate,calcitonin,digoxin immune,liothyronine(T 3 ) </li></ul>
  9. 9. ORPHAN DRUG <ul><li>With a single diagnosed patient only, ribose-5-phosphate isomerase deficiency is presently considered the rarest genetic disease. </li></ul><ul><li>No single cutoff number has been agreed upon for which a disease is considered rare. A disease may be considered rare in one part of the world, or in a particular group of people, but still be common in another. </li></ul>
  10. 10. Factors governing choice of route of drug administration <ul><li>Physical and chemical properties of the drug(solid/liquid/gas;solubility,stability,pH) </li></ul><ul><li>Site of desired action </li></ul><ul><li>Rate and extent of absorption of the drug from different routes </li></ul><ul><li>Effect of digestive juices and first pass metabolism on the drug </li></ul><ul><li>Rapidity with which the response is desired </li></ul><ul><li>Accuracy of dosage required </li></ul><ul><li>Condition of the patient </li></ul>
  11. 12. Special features of transdermal drug delivery system <ul><li>These are devices in form of adhesive patches of various shapes and sizes,which deliver the contained drug at a constant rate into systemic circulation. </li></ul><ul><li>The drug is held in a reservoir between an occlusive backing film and a rate controlling micropore membrane,the under surface of which is smeared with an adhesive impregnated with priming dose of drug that is protected by another film to be peeled off just before application. </li></ul>
  12. 15. 1 st Pharmacokinetic Effect of Drug <ul><li>It is transport of drug across biological membranes. </li></ul><ul><li>Drugs are transported across the membranes by (a)Passive diffusion and filtration (b) specialized transport. </li></ul>
  13. 16. Influence of pH on passive diffusion <ul><li>Most drugs are weak electrolytes, i.e. their ionization is pH dependent(contrast to strong electrolytes---which are nearly completely ionized at acidic as well as alkaline pH). </li></ul><ul><li>Ions being lipid insoluble ,do not diffuse and a pH difference across a membrane can cause differential distribution of weakly acidic and weakly basic drugs on the 2 sides. </li></ul>
  14. 18. Fate of drug after its absorption <ul><li>It will bound to plasma protein……inactive form </li></ul><ul><li>Free (unbound) form of drug will go to its site of action or to storage tissue. It may excrete out in unchanged form or 1 st it may be metabolized,then excreted out by excretory organs. </li></ul>
  15. 20. Pharmacokinetic difference between formal tissues and brain <ul><li>Usual capillaries have large intercellular pores through which even large lipid insoluble molecules diffuse. </li></ul><ul><li>Tight junctions in brain capillary and glial cell processes/choroidal epithelium don’t allow passage of non-lipid soluble molecules/ions. </li></ul>
  16. 22. Bioavailability,plasma concentration and therapeutic concentration of drug <ul><li>Some drugs absorb slowly…exhibiting small AUC and some have large AUC accordingly. </li></ul>
  17. 27. Control release (CR) drugs <ul><li>Usually 30% of the dose of CR-drug outside the semipermeable membrane is released immediately. </li></ul><ul><li>70% of the dose is released slowly through the membrane over the next 4-8 hours. </li></ul>