Pharmacologic Principles PDF

Pharmacologic Principles  Pharmacologic Principles Drug(Dutch droog,- dry) Any chemical that affects the processes of a living organism Therapeutic drugs, often called medicines Dried plants were the greatest source of medicines thus the word drug was applied  Pharmaco...

Pharmacologic Principles  Pharmacologic Principles Drug(Dutch droog,- dry) Any chemical that affects the processes of a living organism Therapeutic drugs, often called medicines Dried plants were the greatest source of medicines thus the word drug was applied  Pharmacologic Principles Pharmacology (from Greek φάρμακον, pharmakon, "drug"; and - λογία, -logia) is the study of drug action. practiced by pharmacologists is the study of drugs and their actions on living organisms  Subdisciplines clinical pharmacology - the medical field of medication effects on humans pharmacognosy – study of deriving medicines from plants. Pharmacotherapeutics - study of the use of drugs in the treatment of disease Pharmacy - study of preparing and dispensing of medications toxicology study of harmful effects of drugs  DEFINITION OF TERMS Drug ❑ Are chemical substances that have an effect on living organism Therapeutic Drugs or Medicines ❑ Drugs used for the prevention or treatment of disease Prescription Written direction for the preparation and administration of drug.  THERAPEUTIC METHODS Definition Approaches to therapy of terms Drug therapy Diet therapy Physiotherapy Psychological therapy  DRUG CLASSIFICATION 01 02 According to which body According to their system therapeutic use/clinical Affecting the CNS indication Affecting the CVS Antacids Affecting the GI Antibiotics Antihypertensives Diuretics  DRUG CLASSIFICATION According to physiologic or chemical action Beta adrenergic blockers Calcium channel blockers Anticholinergics and cholinergics Classified as prescription or non prescription Prescription non prescription or OTC- w/o prescription Pharmacologic Principles: Drug Names Chemical name The drug’s chemical composition and molecular structure Generic name (nonproprietary name) Name given by the United States Adopted Name Council The 1st letter of the GN is not capitalized Trade name (proprietary name) The drug has a registered trademark; use of the name restricted by the drug’s owner (usually the manufacturer) The 1st letter of the TN is capitalized. Pharmacologic Principles: Drug Names Chemical name (+/-)-2-(p-isobutylphenyl) propionic acid Generic name ibuprofen Trade name Motrin  Regulated drugs Drugs with potential abuse Definition of Terms: Drug abuse - excessive self administration of a drug that could result in addiction Addiction - drug seeking behavior in which the abuser is unable to control the desire for the drug Withdrawal - physical effects resulting when drug is discontinued in an individual who is addicted to a drug  Physical dependence – withdrawal of the drug produces physical effects on the individual. Psychological dependence (habituation) – Intense desire or craving for the drug when it is not available(no physical or withdrawal effects)  Schedule 1: drugs with high abuse potential, no accepted medical use Schedule II: high potential for drug Controlled abuse, can lead to strong physical and psychological dependency, ex. Substance Meperidine, Morphine, Amphetamine Schedule Schedule III: medically-accepted drugs, potential abuse is less than 1 & II. -may cause dependence, ex. Codeine  Schedule IV: medically- accepted drugs, may cause dependence – Diazepam, Phenobarbital Controlled Schedule V: medically- Substance accepted drugs Schedule – Very limited potential for dependence – Ex. Opioid-controlled substance for diarrhea or cough, Lomotil, Robitussin  Classes of Drug Abuse Relieves anxiety and induce CNS sleep,dilatepupils, decrease Depressant temp. Ex. Alcohol, sleeping pills Increase alertness Stimulants Flushing, dry mouth, inc HR, inc BP Hear, see , feel something that is not there Hallucinogens Lysergic acid diethylamide,MESCALINE  Classes of Drug Abuse Opiates Relieves pain ex. Morphine, heroine,codeine Consrict pupil Volatile solvents Ex. Rugby  Nursing responsibilities Account for all controlled drugs Keeps special controlled substance record for required information Countersign all discarded or wasted medication Keep all controlled drugs locked up  Pharmacologic Principles Pharmaceutics Pharmacokinetics Pharmacodynamics Pharmacotherapeutics Pharmacognosy  Pharmacologic Principles Pharmaceutics The study of how various drug forms influence pharmacokinetic and pharmacodynamic activities  Pharmacologic Principles Pharmacokinetics The study of what the body does to the drug: – Absorption – Distribution – Metabolism – Excretion  Pharmacologic Principles Pharmacodynamics The study of what the drug does to the body: The mechanism of drug actions in living tissues  Pharmacologic Principles Pharmacotherapeutics The use of drugs and the clinical indications for drugs to prevent and treat diseases  Pharmacologic Principles Pharmacognosy The study of natural (plant and animal) drug sources  Drug Absorption of Various Oral Preparations Liquids, elixirs, syrups Fastest Suspension solutions  Powders  Capsules  Tablets  Coated tablets  Enteric-coated tablets Slowest  The rate at which a drug leaves its site of administration, and the extent to which absorption Pharmacokinetics: occurs. – Bioavailability-fraction of Absorption administered drug that gains access to the systemic circulation in a chemically unchanged form.  Pharmacokinetics: Absorption Factors That Affect Absorption Administration route of the drug Food or fluids administered with the drug Dosage formulation Status of the absorptive surface-microvilli Rate of blood flow to the small intestine - Acidity of the stomach Status of GI motility Anything that delays the transport of drug from the stomach to the intestine delays the absorption of drug  Pharmacokinetics: Absorption Routes A drug’s route of administration affects the rate and extent of absorption of that drug. – Enteral – Parenteral – Topical  PHARMACOKINETICS ABSORPTION Categories of drug administration – Enteral Oral, rectal, nasogastric Must be dissolve in body fluids Conversion process involved if administrating drug with or without meal – Parenteral Subcutaneous (subQ), intramuscular (IM), intravenous (IV) Rate of blood flow to the tissue Cooling the site of injection is a factor – Percutaneous Inhalation, sublingual, topical  First-Pass Effect The metabolism of a drug and its passage from the liver into the circulation. A drug given via the oral route may be extensively metabolized by the liver before reaching the systemic circulation (high first-pass effect). The same drug—given IV—bypasses the liver, preventing the first-pass effect from taking place, and more drug reaches the circulation. First-Pass Effect  First-Pass Effect Routes that bypass the liver: – Sublingual Transdermal – Buccal Vaginal – Rectal* Intramuscular – Intravenous Subcutaneous – Intranasal Inhalation *Rectal route undergoes a higher degree of first- pass effects than the other routes listed.  Pharmacokinetics: Absorption Parenteral Route Intravenous* Intramuscular Subcutaneous Intradermal Intraarticular *Fastest delivery into the blood circulation  Pharmacokinetics: Absorption Topical Route Skin (including transdermal patches) Eyes Ears Nose Lungs (inhalation) Vagina  Absorption of Drugs 1. Oral (swallowed) may be slower and less complete than parenteral (non-oral) routes 2. Sublingual (under the tongue). Permits direct absorption into the systemic venous circulation thus avoiding the first pass effect 3. Rectal (suppository). Useful for patients who cannot take oral medications (eg, because of nausea and vomiting).  4. Intramuscular. Absorption is sometimes faster and more complete than after oral administration. Large volumes may be given. Absorption 5. Subcutaneous. Slower absorption than intramuscular. of Drugs Large volumes are not feasible. 6. Inhalation. It provides rapid absorption because of the large surface area available in the lungs.  7. Topical. Application to the skin or mucous Absorption of Drugs membrane of the nose, throat, airway, or vagina for a local effect. 8. Transdermal. Application to the skin for systemic effect. 9. Intravenous. Instantaneous and complete absorption (by definition, 100%)  Distribution of Drugs Refers to the ways in which drugs are transported by the circulating body fluids to the sites of action, metabolism & excretion. Depends on the: Blood flow- rate of uptake of the drugs Solubility- high lipid content Binding to plasma proteins-drugs become trapped and in effect, INACTIVE ability to cross special barriers -contain specialized capillaries. Lipid soluble drugs readily penetrate into the CNS.  Pharmacokinetics: Metabolism (also known as Biotransformation) The biologic transformation of a drug into an inactive metabolite, a more soluble compound, or a more potent metabolite. It is the process by which the body inactivates drugs Liver (main organ) Kidneys Lungs Plasma Intestinal mucosa  Pharmacokinetics: Metabolism Factors that decrease metabolism: Cardiovascular dysfunction Renal insufficiency Starvation Obstructive jaundice Slow acetylator Erythromycin or ketoconazole drug therapy Pharmacokinetics: Metabolism Factors that increase metabolism: Fast acetylator Barbiturates Rifampin therapy  Pharmacokinetics: Metabolism Delayed drug metabolism results in: Accumulation of drugs Prolonged action of the effects of the drugs Stimulating drug metabolism causes: Diminished pharmacologic effects  Pharmacokinetics: Excretion The elimination of drugs from the body Kidneys (main organ) Liver Bowel – Biliary excretion – Enterohepatic circulation Kidney-main organ for drug excretion  Pharmacokinetics Half-Life The time it takes for one half of the original amount of a drug in the body to be removed. A measure of the rate at which drugs are removed from the body. Example: Patient is given 100mg of a drug that has a half- life of 12 hours.  Pharmacodynamics It is a branch of pharmacology that deals with the mechanism of action, pharmacological effects, indication and contraindication of use and adverse effects of drugs. Is a study of how the drug manipulates the body cells. What the drug does to the body The better the fit ,the better the response Pharmacodynamics Drug actions: The cellular processes involved in the drug and cell interaction Drug effect: The physiologic reaction of the body to the drug  Pharmacodynamics Onset The time it takes for the drug to elicit a therapeutic response Peak The time it takes for a drug to reach its maximum therapeutic response Duration The time a drug concentration is sufficient to elicit a therapeutic response  Pharmacodynamics: Mechanisms of Action The ways by which drugs can produce therapeutic effects: Once the drug is at the site of action, it can modify the rate (increase or decrease) at which the cells or tissue's function. A drug cannot make a cell or tissue perform a function it was not designed to perform.  Pharmacodynamics: Mechanisms of Action Receptor Enzyme interaction Nonspecific interaction interactions  DRUG Receptor  Receptor Interactions Lock and key mechanism Agonist Receptor Agonist-Receptor Interaction  Receptor Interactions Induced Fit Receptor Perfect Fit!  Receptor Interactions Competitive Inhibition Antagonist Receptor Antagonist-Receptor DENIED! Complex  Receptor Interactions Non-competitive Antagonist Inhibition Agonist Receptor DENIED! ‘Inhibited’-Receptor  PHARMACODYNAMICS DRUG ACTION DESIRED ACTION Expected response Drugs have potential to affect more than one ADVERSE EFFECT OR body system SIDE EFFECT simultaneously producing a response  PHARMACODYNAMICS DRUG ACTION ADVERSE DRUG REACTION (ADR) any noxious, unintended and undesired effect of a drug, which occurs at doses used in human prophylaxis, diagnosis and therapy (WHO) Predictable – had to be measured – Parameter (therapeutic action, side effect, adverse effect, drug interaction)  PHARMACODYNAMICS DRUG ACTION Most common reaction – rash, nausea, itching, thrombocytopenia, vomiting, hyperglycemia, and diarrhea Class of medicine with large account Antibiotics, cardiovascular drug, chemotherapy drugs, analgesics and anti-inflammatory  PHARMACODYNAMICS DRUG ACTION Idiosyncratic Reaction occurs when something unusual or abnormal happens when drug is first administered Overresponse happens in patients' inability to metabolized the drug (genetic defect)  PHARMACODYNAMICS DRUG ACTION Allergic Reaction occurs to patient who has been previously exposed to a drug and have developed antibodies to it from the immune system Anaphylactic Reaction severe life -threatening reaction that causes respiratory distress and cardiovascular collapse  PHARMACODYNAMICS DRUG ACTION Carcinogenecity the ability of a drug to induced living cells to mutate and became cancerous Teratogen a drug that induced birth defect  PHARMACODYNAMICS DRUG ACTION Variable factors influencing drug action – Age – Body Weight – Metabolic Rate – Illness – Psychological Aspect – Tolerance – Dependence – Cummulative Effect  PHARMACODYNAMICS DRUG ACTION Psychological Aspect Placebo effect – patient’s positive expectation about treatment and care received can positively affect the outcome Placebo – A drug dosage form with no pharmacologic activity Nocebo Effect – patient’s negative expectation about treatment and care received  PHARMACODYNAMICS DRUG ACTION TOLERANCE occurs when person begins to require a higher dosage to produce the same effects that a lower dosage once provided DEPENDENCE Addiction/ habituation, occurs when a person is unable to control the ingestion of drugs Physical and Psychological Dependence  PHARMACODYNAMICS DRUG ACTION Cumulative Effect A drug may accumulate in the body if the next dose is administered before the previously administered dose has been metabolized or excreted. Excessive Drug Accumulation may result to Toxicity  PHARMACODYNAMICS DRUG INTERACTION Occurs when the action of one drug is altered by the action of another drug Two ways – Increase the action of one or both drugs – Decrease the effectiveness of one or both drugs  PHARMACODYNAMICS DRUG INTERACTION Categories of Drug Interaction altering: Absorption Distribution Metabolism Excretion  Additive effect- 2 drugs with similar actions are taken for a double effect. Example: propoxypene + aspirin= added analgesic effect Synergestic effect: the combined effect of 2 drugs is greater than the sum of the DRUG effect of each drug given alone. INTERACTION Example: aspirin +codeine=much greater analgesic effect. Antagonistic effect : one drug interferes one another. Example: tetracycline+ antacid= decreased absorption of tetra  DRUG INTERACTION Displacement: the displacement of the 1st drug by a 2 nd drug increases the activity of the 1st drug. – example: warfarin +valproic acid=increased anticoagulant effect – Interference: the 1st drug inhibit the metabolism or excretion of the 2 nd drug causing the increased activity of the 2nd drug. Example: probenecid + spectinomycin=prolong the activity of antibiotic.  PHARMACODYNAMICS DRUG INTERACTION Incompatibility The first drug is chemically incompatible with the second drug, causing deterioration when both drug are mixed in the same syringe or solution Pharmacotherapeutics: Types of Therapies Acute therapy Maintenance therapy Supplemental therapy Palliative therapy Supportive therapy Prophylactic therapy  Pharmacotherapeutics: Monitoring The effectiveness of the drug therapy must be evaluated. One must be familiar with the drug’s intended therapeutic action (beneficial) and the drug’s unintended but potential side effects (predictable, adverse drug reactions). Pharmacotherapeutics: Monitoring Therapeutic index Drug concentration Patient’s condition Tolerance and dependence Interactions Side effects/adverse drug effects  Pharmacotherapeutics: Monitoring Therapeutic Index The ratio between a drug’s therapeutic benefits and its toxic effects  Pharmacotherapeutics: Monitoring Tolerance A decreasing response to repetitive drug doses  Pharmacotherapeutics: Monitoring Dependence A physiologic or psychological need for a drug  Pharmacotherapeutics: Monitoring Interactions may occur with other drugs or food Drug interactions: the alteration of action of a drug by: Other prescribed drugs Over-the-counter medications Herbal therapies  Factors influencing drug action Age- infants & elderly tend to be the most sensitive to the effects of drugs. Body weight- over wt.- increase dosage Metabolic rate- smoking enhances the metabolism of theophylline. Illness- shock  Pharmacotherapeutics: Monitoring Medication Misadventures Adverse drug events ALL are preventable An injury resulting from medical intervention related to a drugs Adverse drug reactions Inherent, not preventable event occurring in the normal therapeutic use of a drug Any reaction that is unexpected, undesirable, and occurs at doses normally used  Pharmacotherapeutics: Monitoring Some adverse drug reactions are classified as side effects. Expected, well-known reactions that result in little or no change in patient management Predictable frequency The effect’s intensity and occurrence is related to the size of the dose  Pharmacotherapeutics: Monitoring Adverse Drug Reaction An undesirable response to drug therapy Idiosyncratic-occurs when something unusual or abnormal happens when a drug is 1st administered. Hypersensitivity reactions Drug interactions  Pharmacotherapeutics: Monitoring Iatrogenic Responses Unintentional adverse effects that are treatment- induced Dermatologic Renal damage Blood dyscrasias Hepatic toxicity  Pharmacotherapeutics: Monitoring Other Drug-Related Effects Teratogenic- drug that induces birth defects Mutagenic-drug that causes an alteration in the genetic material Carcinogenic- a drug to induce living cells to mutate and become cancerous. Thank you