Phases of Drugs PowerPoint Presentation PDF

PHASES OF DRUG Professors: Marison Ann C. Bunyi, RN, MAN, USRN Carol S. Samantilla, RN, RM, MSN, MAN John Nichol Angeles, RN, MAN Learning Objectives After the discussion of this lesson, students will be able to: Define the terminologies related understanding the different drugs i...

PHASES OF DRUG Professors: Marison Ann C. Bunyi, RN, MAN, USRN Carol S. Samantilla, RN, RM, MSN, MAN John Nichol Angeles, RN, MAN Learning Objectives After the discussion of this lesson, students will be able to: Define the terminologies related understanding the different drugs identify different factors that determine proper dosing schedules. Provide detailed information on drugs adverse reaction, Toxicity, Interactions w/ other drugs, Incompatibilities, side effects, and the use of Antidotes Importance of understanding the drugs we’re putting into our bodies, and how being informed about our medications helps us safeguard our health.  Medication plays an important role in managing disease, but it can also be quite harmful if taken incorrectly. It’s not enough to know that you take a blue capsule and a yellow tablet twice a day. You need to know the names of your prescriptions, and understand the important details about how they work. Ask your self: What is the name of the medicine? Why do I need to take it? When and how should I take it? With water? With food? On an empty stomach? How much should I take? What should I do if I miss a dose? What side effects could be caused by the medication? Which ones should I call the doctor about? Are there any foods or medicines I should avoid while taking this medicine? Will this medication change how my other medicines work? DRUG THERAPY Treatment of the disease using drugs. Phases of Drugs| PHARMACODYNAMICS How drug act on the body? Refer to a drug’s effect on cellular physiology and biochemistry and drug mechanism of action. Drug usually works in 4 ways: 1. Replace or act as substitutes for missing chemicals 2. Increase or stimulate certain cellular activities 3. Depress or slow cellular activities 4. Interfere with the functioning of foreign cells Pharmacodynamics events A. Minimum Effective Concentration- minimum amount of drug dose needed to produce the desired drug response. B. Onset of Action- the time it takes to reach MEC after a drug is administered. C. Peak Action- when drugs reach its highest blood or plasma concentration. D. Duration of Action- length of the time the drug has pharmacologic effect. Pharmacodynamics events E. Half Life (t1/2)- time it takes for half of the drug concentration to be eliminated. Ex: 650 mg of aspirin is administered with half-life of 3 hour. 3hr- 325 (50) 6hr- 162(25) 9hr- 81(12.5) 12hr- 40(6.25) 15hr- 20(3.1) 18hr- 10(1.55) Pharmacodynamics events F. Loading dose- when immediate drug response is desired, a large initial dose known as loading dose of drug is given to achieve MEC in plasma. Pharmacodynamics events G. Drug- usually combine with drug receptor to produce a response. A receptor is a protein embedded in a cell membrane or in cytoplasm that will facilitate the communication between drug and cell. A receptor can be: 1. Cell membrane- Drug binding on cell surface, drug activate the cell and response initiated. 2. Ligand ion channel- in this receptor, the channel open allowing the flow of ion in and out of the cell. 3. G protein- could receptor: Drug-----Receptor-----G protein-----Effector 4.Transcription factor- these factors found on DNA within the cell nucleus, where activation is prolonged. Pharmacodynamics events H. Agonist- drug interact with receptor to produce a response. Example: Cimetidine block H2 blocker- inhibit gastric secretion in peptic ulcer. I. Non-Selective Drug- Drug that act at different receptor. Example: Epinephrine act on alpha receptor Inc. BP, beta 1 receptor Inc HR, beta 2 receptor dilate the lung. A drug may interact with specific receptor sites DRUG- ENZYMES INTERACTIONS Drugs can also cause an effects by interfering with the enzymes system that act as a catalyst for various chemical reactions. occurs, if one single step in one of the many enzymes system is blocked ,the normal cell function is disrupted. Selective TOXICITY The ability of the drug to work only those system found in foreign cells Ideally antibiotic /chemotherapeutic drugs only in the structures and processes only found in the pathogens Phases of Drugs | PHARMACOKINETICS How the body acts on the drug? Refers to the movement of a drug across body membranes to reach its target organ Involves 4 (four) stages of drug movement: - Absorption - Distribution - Metabolism - Excretion PHARMACOKINETICS | ABSORPTION Refers to the movement of a drug from its administration site through or across tissue into the systemic system. Degree and rate of absorption depend on: - Administration route - Patient’s age and physical condition - Lipid and water solubility of the drug - Potential interaction with other drugs or food Mechanism of absorption, such as passive transport (diffusion, passive diffusion-mediated diffusion) active transport or pinocytosis) PHARMACOKINETICS | ABSORPTION Absorption continuous What happens to a drug from the time it is introduced to the body until it reaches the circulating fluids and tissues?  Through the GI tract: orally or rectally  Through the mucous membranes  Through the skin  Through the lung  Through the muscle or the subcutaneous tissue PHARMACOKINETICS | ABSORPTION Medication Administration Routes determine absorption A. Oral route Safest and most frequently used B. Intravenous injection More likely to cause toxic effects C. Intramuscular injection Takes time for absorption Allows the medication to be absorbed into the bloodstream quickly. D. Subcutaneous injection Timing of absorption varies with Sub-Q injection PHARMACOKINETICS | DISTRIBUTION Refers to the movement of drug from the systemic circulation into the tissue Maybe affected by several physiologic factors including: - Blood brain barrier - Cardiac output - Body composition (amount of adipose tissue) - Blood supply to target organ - Degree of vessel constriction or dilatation and the degree in which the drug binds to plasma protein such as albumin PHARMACOKINETICS | DISTRIBUTION Factors Affecting the Distribution of Drugs Lipid solubility of the drug Ionization of the drug Perfusion of the reactive tissue Highly lipid-soluble drugs given by intravenous, or inhalation methods are initially distributed to organs with high blood flow. Less vascular but more bulky tissues (such as muscle and fat) take up the drug—plasma concentration falls, and the drug is withdrawn from these sites. PHARMACOKINETICS | DISTRIBUTION Protein Binding Protein-drug complex is relatively large and cannot enter into capillaries and then into tissues to react. Some drugs are tightly bound and are released very slowly. Some drugs are loosely bound. Some drugs compete with each other for protein binding sites.  PHARMACOKINETICS | METABOLISM Refers to alteration of a drug from its dosage form to a more water soluble form that can be excreted *Usually occurs in the - liver, - may occur in plasma, kidneys or interstitial membranes Maybe affected by: Genetics, patient’s age, physical condition or, the drug itself ( metabolism for drug activity or lipid solubility)  PHARMACOKINETICS | METABOLISM First pass Effect Can influence the effectiveness of orally administered drug, which pass through the liver and are partially metabolized before entering the systemic circulation or a large percentage of the oral dose is destroyed at the liver and never reaches the tissues. Usually requires higher doses; some drugs have almost complete first pass metabolism and are ineffective when given orally  PHARMACOKINETICS | METABOLISM Biotransformation Liver – the single most important site of drug metabolism or biotransformation, the process by which drugs are changed into new, less active chemicals.  PHARMACOKINETICS | EXCRETION Refers to elimination of a drug from the circulation (metabolite or unchanged drug)  Major excretion routes: o Kidneys via urine (Play he important role) o Liver via the bile o Feces o Lungs via exhaled air o Breast milk  Minor excretion routes : Saliva , tears , sweat The most important excretory organs are the kidney and liver.  PHARMACOKINETICS | EXCRETION Factors that determine proper dosing schedules Route of administration - area of the body where drug absorption will take place, bioavailability may change when route of administration is changed Onset action - Time interval from when the drug is administered until its therapeutic effects begin Peak concentration level - maximum blood concentration level achieved through absorption, at this level, most of the drug reaches the sites of action and provides the therapeutic response.  PHARMACOKINETICS | EXCRETION Factors that determine proper dosing schedules Duration of Action - Length of time a drug produces its therapeutic effect Bioavailability - percentage of drug absorbed into systemic circulation for activity; (ex: drugs injected I.V. have 100 % bioavailability) Drug Half Life - Time required for a drug’s plasma concentration to decrease 50% Mechanisms of Pharmacokinetics Pharmacokinetics affect the amount of a drug that reaches reactive tissues. Very little of an oral dose of a drug reaches reactive sites. Half-life The time it takes for the amount of drug in the body to decrease to one-half of the peak level it previously achieved Ex. 20 mg of a drug with a half-life of 2 hours 10 mg will remain 2 hours after administration 5 mg will remain for another 2 hours 2.5 mg will remain for another 2 hours 1.25 mg will remain for another 2 hours 0.625 mg will remain for another 2 hours 0.3125 mg will remain for another 2 hours 0.15625 mg will remain for another 2 hours 0.078125 mg will remain for another 2 hours Phases of Drugs | PHARMACOTHERAPEUTICS Refers to the use of drugs to treat a specific disease or produced a desired effect. TYPES OF DRUG THERAPY: Acute Emperic Supportive Palliative Maintenance Supplemental Replacement Phases of Drugs | PHARMACOTHERAPEUTICS Involves several therapeutic steps :  Assessing the nature and extent of the patient’s health problems.  Assessing the therapy options - Selecting type of therapy  Implementing the therapy  Monitoring effectiveness of therapy and reassessing the problem Phases of Drugs | PHARMACOTHERAPEUTICS Affected by various factors  Patient’s disease or disorder  Route of administration  Patient’s body size, weight, sex, and past or current medical condition  Psychological and emotional issues  Drug tolerance and dependence Phases of Drugs | PHARMACOTHERAPEUTICS LOADING DOSE Refers to administration of one or more doses at the onset of therapy to quickly reach the therapeutic blood level and hasten a therapeutic. Commonly larger than the maintenance dose Phases of Drugs | PHARMACOTHERAPEUTICS Drug Efficacy Refers to a drug’s maximal effectiveness measured by the:  Patient’s vital signs,  Body weight  Easing of symptoms that the drug is expected to relieve. The nurse can document efficacy using these parameters. Phases of Drugs | PHARMACOTHERAPEUTICS Therapeutic Drug Level Refer to drug levels that provide adequate action but minimal adverse effect. May be monitored to: Individualize drug dose Evaluate toxicity Monitor compliance ADVERSE REACTION ADVERSE REACTION -Refers to the unwanted or potentially harmful drug effect (All drugs have one or more adverse reaction in addition to producing a desired effect) TYPES OF ADVERSE REACTION: 1. May range from: a) mild responses that resolve spontaneously or disappear upon discontinuing the drug b) To debilitating potentially chronic or life threateningproblems ADVERSE REACTION TYPES OF ADVERSE REACTION: 2. Reactions associated with starting a new drug- occur shortly after starting a drug but lessen with time. 3. Reaction inseparable from drug’s intended effect 4. Dose related reaction Includes reactions related to drugs primary effect and secondary effect and overdose Can be prevented in most cases with careful prescribing and administration ADVERSE REACTION TYPES OF ADVERSE REACTION: 5. Sensitivity related reaction- hypersensitivity or an allergic response to a drug or one of its components (can be dose related) *In hypersensitivity or allergic reaction, sensitized patient is exposed to a drug that elicits an antigen-antibody reaction. Reactions may be immediate (resulting in anaphylaxis or uticaria) or delayed (as serum sickness) ADVERSE REACTION TYPES OF ADVERSE REACTION: 6. Iatrogenic effect Reaction that mimics a pathologic condition, (like when aspirin or non steroidal anti- inflammatory drugs cause GI irritation and bleeding. 7. Toxicity- reaction that occurs when drug levels exceed the therapeutic range, possibly causing additional adverse reaction  May develop because of overdose resulting from failure to consider hepatic impairment, renal function, or the patient’s age.  May result from the patient misunderstanding dosage or administration instruction.  May require dosage modification  Can be prevented closely by monitoring established blood levels ADVERSE REACTION TYPES OF ADVERSE REACTION: 8. Idiosyncrasy an unexpected or peculiar response to drug (Diphenhydramine cause hyper excitability in children) 9. Miscellaneous reaction include blood dyscrasias, nephrotoxicity, hepatic toxicity, carcinogenicity , teratogenicity , photosensitivity and disease related effects INTERACTION INTERACTION  Refer to alterations of the pharmacokinetic , pharmacodynamics, or pharmacotherapeutic characteristics of drugs which affect overall therapeutic effects.  Can produce effects like increased or decreased metabolism ,increased or decreased excretion. INTERACTION  Maybe the result of other drugs , food , herbs or the environment Ex: taking monoamine oxidase inhibitors (MAO INHIBITORS) with thymine-containing foods (cheese , beer) may lead to hypertensive crisis  Include contraindications or precautions which warn against the drug use  May be desired in some cases for their therapeutic effect benefits (ex: one drug may block the elimination of another drug in systemic circulation , longer)  May effect and alter laboratory result INCOMPATIBILITIES INCOMPATIBILITIES May result from chemical or physical reactions between two or more drugs. May occur when : 1. Preparing IV admixtures 2. Administering medications in I.V bolus, or piggyback 3. Mixing medications in syringe Usually seen as crystallization of solution or change in solution color PHARMACOKINETIC INTERACTIONS Altered Drug Absorption- result from changes in stomach pH presence or absence of food in the GI tract presence of other drug or herbs in the stomach Toxicity can occur when protein – bound drugs compete from protein binding sites ,causing the drugs to displace to another circulation PHARMACOKINETIC INTERACTIONS Induction or Inhibition of hepatic metabolism occur in increase and decrease of some metabolized drugs Altered Drug Excretion planned or coordinated to enhance or inhibit excretion of certain drugs ex: probenecid may administer with penicillin to delay renal excretion and prolong antibiotics effects. PHARMACODYNAMIC INTERACTIONS Adding Effect Combining two or more drugs to cause an effect equal to the sum of their separate effects Ex: aspirin + codeine= pain relief Synergism Combining 2 or more drugs to cause an effect greater than the sum of their separate effect. Ex: Promethazine (phenergan )+ Meperidine (demerol) provides greater pain relief than meperidine alone PHARMACODYNAMIC INTERACTIONS Potentiation Type of synergism in which one or two more combined drugs exerts an action greater than if it were given alone ex: Vit. D helps with the absorption and action of calcium in the body. Antagonistic effect combining 2 or more drugs to produce an effect less than the sum of their separate effects (Drug antidote) chemical that counteracts (neutralizes) the effects of another drug or a poison. DRUG ANTIDOTE Example: Drug antidote Activated charcoal Banana vinegar,lemon juice, canned fruit juice. EGGs DRUGS Diazepam/naloxone combination is the most efficient antidote to reverse tramadol-induced CNS toxicity Example: Drug antidote Acetylcysteine for acetaminophen poisoning Activated charcoal for most poisons Atropine for organophosphates and carbamates Digoxin immune fab for digoxin toxicity Dimercaprol for arsenic, gold, or inorganic mercury poisoning Flumazenil for benzodiazepine overdose Methylene blue for drug-induced methemoglobinemia Naloxone for opioid overdose Pralidoxime for poisoning by anti-cholinesterase nerve agents. THANK YOU! 