nursunf INTRODUCTION TO PHARMACOLOGY 1.pptx

pharmvo for nurses

1. INTRODUCTION TO PHARMACOLOGY ANTHONY M. R.N, BScN (UON)

2. Pharmacology introduction DR NARENDRA KUMAR Assistant Professor

3. Introduction Pharmacology Living Organism Physiology Biochemistry PHARMACOLOGY DRUG

4.   ? DRUG As per WHO Scientific group “Any Substance or product that is used and intended to be used to modify or explore the physiological system or pathological state for the benefit of the recipient “

5. Drug categories Prescription drugs Are used under only medical supervision and dispensed by an order of medical practitioner only OTC drugs Can be sold over the counter without prescription

6. Sub divisions of Pharmacology

7. A drug generally has three categories of names: Chemical name It describes the substance chemically, e.g. 1-( Isopropylamino )-3-(1-naphthyloxy) propan-2 – ol for propranolol. (b) Non-proprietar y / official name / Approved name N ame in the official books accepted all over the world Proprietary (Brand) name Crocin for Paracetamol DRUG NOMENCLATURE

8. Essential medicines , as defined by the WHO are "those drugs that satisfy the health care needs of the majority of the population; they should therefore be available at all times in adequate amounts and in appropriate dosage forms, at a price the community can afford." Essential medicines

9. These are drugs or biological products for diagnosis/treatment/ prevention of a rare disease or condition, or a more common disease (endemic only in resource poor countries) 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 nitrite , fomepizole, liposomal amphotericin B ,, rifabutin,, somatropin, digoxin immune Fab (digoxin antibody), liothyronine (T3) and many more. Governments in developed countries offer tax benefits and other incentives to pharmaceutical companies for developing and marketing orphan drugs (e.g. Orphan Drug Act in USA). Orphan Drugs

10. Definitions Pharmacokinetics The process by which a drug is absorbed , distributed , metabolized and eliminated by the body Pharmacodynamics The interactions of a drug and the receptors responsible for its action in the body

11. The Life Cycle of a Drug (pharmacokinetics) Absorption Distribution Degradation Excretion

12. Slow Absorption Orally (swallowed) through Mucus Membranes Oral Mucosa (e.g. sublingual) Nasal Mucosa (e.g. insufflated) Topical/Transdermal (through skin) Rectally (suppository)

13. Faster Absorption Parenterally (injection) Intravenous (IV) Intramuscular (IM) Subcutaneous (SC) Intraperitoneal (IP) Inhaled (through lungs)

14. Fastest Absorption Directly into brain Intracerebral (into brain tissue) Intracerebroventricular (into brain ventricles) General Principle: The faster the absorption, the quicker the onset, the higher the addictiveness, but the shorter the duration

15. Absorption: Solubility Water-soluble Ionized (have electrical charge) Crosses through pores in capillaries, but not cell membranes Lipid(fat)-soluble Non-ionized (no electrical charge) Crosses pores, cell membranes, blood-brain-barrier Dissociation constant or pKa  indicates the pH where 50% of the drug is ionized (water soluble) and 50% non-ionized (lipid soluble); pKeq = pH + log [X]ionized/[X]non-ionized This affects a drug's solubility, permeability, binding, and other characteristics.

16. Bioavailability The fraction of an administered dose of drug that reaches the blood stream. What determines bioavailability? Physical properties of the drug (hydrophobicity, pKa, solubility) The drug formulation (immediate release, delayed release, etc.) If the drug is administered in a fed or fasted state Gastric emptying rate Circadian differences Interactions with other drugs Age Diet Gender Disease state

17. Depot Binding (accumulation in fatty tissue) Drugs bind to “depot sites” or “silent receptors” (fat, muscle, organs, bones, etc) Depot binding reduces bioavailability, slows elimination, can increase drug detection window Depot-bound drugs can be released during sudden weight loss – may account for flashback experiences?

18. Degradation & Excretion Kidneys Traps water-soluble (ionized) compounds for elimination via urine (primarily), feces, air, sweat Liver Enzymes(cytochrome P-450) transform drugs into more water-soluble metabolites Repeated drug exposure increases efficiency  tolerance

19. Excretion: Other routes Lungs alcohol breath Breast milk acidic ---> ion traps alkaloids alcohol: same concentration as blood antibiotics Also bile, skin, saliva ~~

20. Metabolism and Elimination (cont.) Half-lives and Kinetics Half-life: Plasma half-life: Time it takes for plasma concentration of a drug to drop to 50% of initial level. Whole body half-life: Time it takes to eliminate half of the body content of a drug. Factors affecting half-life age renal excretion liver metabolism protein binding

21. Pharmacokinetics The time course and effects of drugs and their metabolites on the body (what the drug does to the body) absorption distribution biotransformation half-life steady-state concentration excretion

22. Pharmacokinetics Absorption the process whereby drug molecules enter the bloodstream affected by the route of administration and the particulars of manufacture, such as the thickness of pill coating, type of filler substance, hardness of tablet Distribution the movement of drug molecules through the bloodstream to the site of action protein-binding affects distribution. The ratio of protein-bound to unbound remains constant, so as unbound molecules pass out of the bloodstream other molecules become unbound

23. Pharmacokinetics Biotransformation the changes in the structure of drug molecules characteristically produced by enzymatic action in the liver most drugs are converted into inactive metabolites, but some are changed to an active form. some drugs are not metabolized and pass from the body unchanged Half-life determined by measuring the amount of time required for a given blood level to decline by 50%