Introduction To Pharmacology PDF

INTRODUCTION TO PHARMACOLOGY ELVIN O. BAQUILLER,RN A drug's action is affected by the quantity of drug tha t reaches the receptor and the degree of attraction (a ffinity) between it and its receptor on the cell's surfa ce. Once bound to their receptor, drugs vary in their ability to produc...

INTRODUCTION TO PHARMACOLOGY ELVIN O. BAQUILLER,RN A drug's action is affected by the quantity of drug tha t reaches the receptor and the degree of attraction (a ffinity) between it and its receptor on the cell's surfa ce. Once bound to their receptor, drugs vary in their ability to produce an effect (intrinsic activity). Refers to the biochemical and physiological effects of drugs on the body and the mechanisms by which these effects are produced. It encompasses how a drug interac ts with cellular receptors, enzymes, or other molecular targets to influence biological functions and processes.  v DISINTEGRATION: Is the P breakdown of tablet into smaller particles. v DISSOLUTION: Dissolving of the v Solid form smaller particles in the GI fluid before absorption. v Liquid form v 1st phase of drug action v RATE LIMITING: Time it takes for the drug to disintegrate and dissolve to become available for the body to absorb it. P v Solid form v Liquid form  P vIs a branch of pharmacology that deals 4 Basic/Key with the process of drug Process/Components movement to achieve drug action within the body. v What the body does to the drug- refers to the study of how the body process drugs.  P vUnderstanding pharmacokinetics is 4 Basic/Key crucial in providing Process/Components essential information and for determining safe, effectiveness, appropriate dosage, frequency, and duration of treatment with a drug to helping optimize therapeutic outcomes and minimize the risk of adverse effects. vThe movement of drug P particles from the GI tract to body fluids by: I. Absorption üMovement of a drug from the site of administration into the bloodstream. üAbsorption determines how long it takes for a drug to take effect. üUsually, the more rapid the P absorption the faster the drug works I. Absorption üDrugs can be absorbed through plasma primarily by: üDoes not require energy to move across the membrane. üRequires a carrier such as an enzymes or protein üEnergy is required for active absorption üProcess by which cells carry drug across their membrane by engulfing the drug particles 01 Refers to the total area available in the body for a drug to be absorbed into the bloodstream. A larger surface area provides more opportunities for a drug to pass through membranes and enter the blood, facilitating 04greater and often faster absorption. 02 Refers to the duration that a drug remains in contact with the absorptive surface (e.g., the lining of the gastrointestinal tract, the skin, or the alveoli in the lungs). This duration is crucial because it affects how much of the drug can be absorbed into the bloodstream. 03 Refers to the blood flow in the body that facilitates the transport of drugs from the site of absorption to the target tissues and organs. Efficient circulation is crucial for the rapid and effective distribution of the drug throughout the body, influencing its therapeutic efficacy. 04 Refers to the ability of a drug to dissolve in a particular solvent, typically the fluids of the gastrointestinal tract (for oral drugs) or other body fluids (for parenteral or topical drugs). Solubility is a critical factor because a drug must be dissolved in these fluids before it can be absorbed into the bloodstream. 05 Refers to the process by which a drug molecule either gains or loses an electric charge, forming ions. This process depends on the drug's chemical structure and the pH of the surrounding environment. Ionization is a crucial factor because it influences the drug's solubility and its ability to cross biological membranes, thereby affecting its absorption into the bloodstream. 06 Refers to the physical and chemical form in which a drug is administered, while "drug concentration" pertains to the amount of the drug present in a given volume or mass of the dosage form. Both factors significantly influence how a drug is absorbed into the bloodstream and, consequently, its efficacy and onset of action.  Bioavailability ( after 07 first pass thru liver) Refers to the proportion of an administered drug that reaches the systemic circulation in an active form and is available to exert its therapeutic effects. It is a critical pharmacokinetic parameter because it determines the drug's efficacy and helps guide dosage requirements. Bioavailability is influenced by several factors, including the drug's formulation, route of administration, and physiological conditions. 08 Refers to how a drug is delivered into the body. It plays a critical role in determining how the drug is absorbed, distributed, metabolized, and eliminated (pharmacokinetics). There are two main categories of routes of administration: enteral and parenteral. 09 Additives vAlter the location of disintegration of drugs as well as increase or decrease the rate of absorption vRefer to substances that are included in drug formulations to enhance or modify the properties of the drug delivery system. These additives can affect how the drug is absorbed and utilized in the body. Additives serve various purposes, such as improving stability, solubility, bioavailability, or controlling the release of the drug 10 vAllows a drug to dissolve only in an alkaline (pH greater than 7.0) environment such as the small intestine. vRefers to a specialized type of coating applied to oral solid dosage forms (such as tablets or capsules) that is designed to protect the drug from being dissolved or degraded in the acidic environment of the stomach. Instead, the coating allows the drug to be released and absorbed in the more neutral to alkaline environment of the small intestine.  Sustained Release 11 Drugs Also known as Extended-release or Controlled-release drugs, are formulations designed to release the active ingredient of a medication gradually over an extended period of time, rather than quickly, like conventional tablets. This gradual release is intended to maintain therapeutic drug levels in the body over a longer duration, compared to immediate-release formulations which release the drug rapidly and achieve peak concentrations relatively quickly. 12 v Smaller the particle, faster the onset. v Also known as Particle Size, plays a significant role in drug absorption and overall bioavailability. It refers to the dimensions of the individual drug particles within a pharmaceutical formulation. Particle size can influence several aspects of drug absorption and pharmacokinetics , Elixirs, Syrups II. Distribution  v The transport of drugs II. Distribution from the blood to the site of action. A drug must be distributed to its site of action to have an effect Ø Drugs are also distributed to tissues where it has no effect. Competition for drug binding sites affects the amount of drug available for action in the body. II. Distribution Ø Volume of Distribution (Vd) ü The degree of distribution of a drug into various body compartments and tissue 01 Refers to the rate at which blood flows through the tissues where the drug is being absorbed. This flow of blood is crucial because it helps transport the drug from the site of absorption (such as the gastrointestinal tract) to the 04 systemic circulation, where it can exert its therapeutic effects. 02 Refers to the ability of a drug to cross biological membranes, such as cell membranes, to enter the bloodstream and reach its target sites within the body. This permeability is crucial for determining how well and how quickly a drug can be absorbed into the systemic circulation. 03 Refers to the extent to which a drug attaches to proteins in the blood, primarily plasma proteins like albumin, globulins, and alpha-1 acid glycoprotein. This binding affects the distribution, availability, and elimination of the drug within the body. 04 Refers to the process by which a drug distributes and accumulates in specific tissues or organs within the body after it has entered the systemic circulation. This distribution is influenced by various factors and plays a significant role in the drug's therapeutic effectiveness and potential side effects. 05 Is a selective permeability barrier that separates the circulating blood from the brain and central nervous system (CNS). It plays a critical role in maintaining the brain's stable environment, protecting it from potentially harmful substances while allowing essential nutrients to pass through. 06 Placenta Refers to the role of the placenta as a barrier and facilitator III. for the transfer of substances, including Metabodrugs, between the maternal blood 04 lism circulation (Biotra and the developing fetus. The nsform placenta is a crucial organ during pregnancy, ation) providing oxygen and nutrients to the fetus while also removing waste products.  III. Metabolism process by which the body changes the (Biotransformation) chemical structure of a drug to another form called a metabolite. a more water soluble compound that can be easily excreted. The major organ for this process is the liver  III. Metabolism Drugs are first absorbed (Biotransformation) through the small intestine then arrive at Content A the liver via the portal circulation vThere they undergo considerable biotransformation before entering the systemic circulation  III. Metabolism (Biotransformation) Content A vThere will be less active drug available for action in the body cells after this first Pass through the Liver 01 ü Hereditary influences on drug responses, refers to variations in which individuals metabolize drugs. ü The rate of drug absorption, hepatic clearance, half- 02 life and duration of action, have all been shown to differ depending upon the time of day a drug is administered.  ü Elimination of the drug from the body is directly 03 influenced by age. Newborns and elderly experience the effects of drugs for longer and the drug takes a lot longer to be eliminated from the body.  When babies are born to term, their renal function is very quick to establish similar levels to adults within one week after birth. If the baby is born prematurely, it can take 8 weeks or more to reach the level of enzymes Content Here necessary. If drugs are given before the You can simply impress your audience and add a unique zing and appeal to your Presentations. Easy to change colors, photos and Text. renal function is at this level, the drug elimination from the body takes a lot longer and so do the effects of the You can simply impress your audience and add a unique zing and appeal drugs to your Presentations. Easy to change colors, photos and Text. You can simply impress your audience and add a unique zing and appeal to your Presentations. Easy to change colors, photos and Text.  v Process where drugs are IV. Excretion removed from the body. are the major organs of excretion. is important for a few drugs. These drugs may be reabsorbed when passing through the intestines from the liver ( enterohepatic re- circulation ). IV. Excretion constitute minor routes of drug excretion elimination of drugs from circulation by all routes. It affects the time a drug remains in the body and the dosage required Renal Clearance & Hepatic Clearance. vThe elimination half-life of a drug is a pharmacokinetic parameter that is defined as the time it takes for the concentration of the drug in the plasma or the total amount in the body to be reduced by 50%. In other words, after one half-life, the concentration of the drug in the body will be half of the starting dose. vDrugs with short half-lives are quickly eliminated from the body. (Ex: analgesics given several X per day) vDrugs with longer half-lives stay in the body longer (ex. Digoxin given once a day) v Refers to the study of the mechanism of drug action on living tissue. vDrugs may increase, decrease or replace enzymes, hormones or body metabolic functions. v Chemotherapeutic drugs alter an abnormal parasite or growth on the body such as bacteria, viruses or neoplastic tissue. examples: antibiotics and antineoplastic drugs. v Therapeutic / Desired effect  (cures a disease or condition) (supports a body function until other treatments or the body's response can take vTherapeutic / Desired over Effect (replaces body fluids or substances) (destroys malignant cells) (returns the body to health) v Adverse Drug Reaction (ADR)  ü Is an unwanted or v Adverse Drug harmful reaction Reaction (ADR) experienced following the administration of a drug or combination of drugs under normal conditions of use and is suspected to be related to the drug. An ADR will usually require the drug to be discontinued or the dose v reduced. Adverse Event ü Event is harm that vAdverse Event occurs while a patient is taking a drug, irrespective of whether the drug is suspected to be the cause. v Side- effect  ü Is any effect caused by a drug other than the intended vSide-effect therapeutic effect, whether beneficial, neutral or harmful. The term ‘side-effect’ is often used interchangeably with ‘ADR’ although the former usually implies an effect that is less harmful, predictable and may not even require discontinuation of therapy (e.g. ankle edema with vasodilators). v Drug Toxicity ü Describes adverse effects of a drug that v Drug Toxicity occur because the dose or plasma concentration has risen above the therapeutic range, either unintentionally or intentionally (drug overdose). v Drug Abuse  ü Is the misuse of vDrug Abuse recreational or therapeutic drugs that may lead to addiction or dependence, serious physiological injury (such as damage to kidneys, liver, heart), psychological harm (abnormal behavior patterns, hallucinations, memory loss), or death. v Hypersensitivity / Allergy Toxicity ü Exaggerated adverse reaction to drug vHypersensitivity / Hypersensitivity ü Refers to excessive or Allergy Toxicity inappropriate immune responses to antigens (allergens) that can cause tissue damage and disease. Allergy Toxicity ü Often called anaphylaxis, is a severe and potentially life- threatening allergic reaction that occurs rapidly. It involves multiple organ systems and requires immediate medical attention. CASE SCENARIO Patient Background: Mary, a 65-year-old woman, presents to her primary care physician with complaints of insomnia. She reports difficulty falling asleep and frequent awakenings throughout the night. Mary has no significant medical history and takes no regular medications. CASE SCENARIO Phase 1: Absorption Mary's physician prescribes her a sedative-hypnotic medication to help improve her sleep. Mary takes the medication orally as directed before bedtime. 1. Describe the process of absorption of the sedative-hypnotic medication taken by Mary. CASE SCENARIO Phase 2: Distribution The sedative-hypnotic medication reaches Mary's brain, where it acts on GABA receptors to promote sedation and sleep. 2. Explain the process of distribution of the sedative-hypnotic medication within Mary's body, including its passage to the brain. CASE SCENARIO Phase 3: Metabolism After a restful night's sleep, Mary's liver metabolizes the sedative-hypnotic medication to facilitate its elimination from her body. 3. Describe the process of metabolism of the sedative-hypnotic medication in Mary's body. CASE SCENARIO Phase 4: Excretion Mary's kidneys filter the metabolites of the sedative-hypnotic medication from her bloodstream into her urine for elimination from her body. 4. Explain the process of excretion of the metabolites of the sedative-hypnotic medication from Mary's body.  THANK YOU…. 1 2 2 3 4 4