Pharm7e-Ch01-Presentation

[Audio] Welcome to the Pharmacology for Technicians Seventh Edition presentation..

[Audio] Chapter 1, Introduction to Pharmacology and Medications in the Body.

[Audio] In the introduction to this chapter, you will learn the definition of pharmacology. In this section, you will also learn about why the pharmacy technician needs to understand and learn about pharmacology. In the drug actions section, you will develop an understanding of the role that receptors play in the body. You will get an overview of the similarities and differences between agonists and antagonists in terms of pharmacology. You will learn the concepts associated with pharmacodynamics: messengers, receptors, and mechanisms of drug action. You will also learn about the four processes of pharmacokinetics: absorption, distribution, metabolism, and excretion..

[Audio] In the drug effects section of this chapter, you will develop an understanding of the terms used to describe the beneficial and harmful effects of drugs. You will discover ways through which common drug interactions occur. In the last section of this chapter, the complementary and alternative medicine section, you will develop an awareness of why pharmacy technicians should be familiar with complementary and alternative therapies..

[Audio] A drug is defined as a substance that changes the way a living organism functions. Pharmacology is defined as the study of drugs, including their origins, properties, actions, and effects on the body. Learning pharmacology can benefit you as a pharmacy technician. Having this knowledge can help when you are preparing and handling medications. It can also help you effectively communicate with patients and with other healthcare workers..

[Audio] Chapter 1, Section 1, Medicinal Drugs. 1.1 Medicinal Drugs.

[Audio] The study and identification of drugs from natural sources is known as pharmacognosy. Various parts of many plants can be used to make drugs. Small molecules are drugs that are produced synthetically from chemical substances. They have a low molecular weight. In general, these drugs are taken orally. In contrast, bioengineered drugs are large protein structures produced by recombinant deoxyribonucleic acid or rDNA technology. They are typically given by injection or infusion..

[Audio] The generic name or nonproprietary name of a drug identifies it without regard to who is manufacturing and marketing it. Examples of generic names include acetaminophen and pantoprazole. The brand name of a drug is the name under which the manufacturer markets the drug. Examples of brand names include Tylenol and Protonix. See Table 1.1 for examples of drug sources, drug names, and their therapeutic effects..

[Audio] Generic names can offer clues for how the drug works or the condition for which the drug is used. For example, atorvastatin and pravastatin are statin drugs used to treat high cholesterol..

[Audio] Chapter 1, Section 2, Drug Actions. 1.2 Drug Actions.

[Audio] Homeostasis is the body's constant effort to maintain a state of health and stability. It is achieved by control and feedback mechanisms that help the body keep its processes in balance. When the body's own processes cannot maintain a healthy state, drugs can be used to help restore or maintain homeostasis. Many drugs work the same way as the body's chemical components for control and feedback..

[Audio] Pharmacodynamics is a branch of pharmacology that studies how drugs act on the body. All medications produce their effects by interacting with biological targets..

[Audio] For the body to maintain homeostasis, cells must perform various tasks and communicate with each other. The principal way in which cells communicate is through the action of chemical messengers. These messengers are chemical substances that cells produce and send out into the body's extracellular fluid. When the messenger reaches the target cell, it binds with a receptor in or on the cell. An effect is then produced in the target cell..

[Audio] To bind with a specific cell type, the messenger must have a chemical structure that is complementary to the structure of that cell's receptors. This property of a receptor site is known as its specificity. The strength by which a specific messenger binds to its receptor site is called its affinity..

[Audio] Drugs act like chemical messengers to perform their specific actions in the body. Like chemical messengers, drugs can also use receptors to bind to the body and cause an effect. A drug that triggers the same cellular response as the body's own chemical messenger is called an agonist. This type of drug enhances the natural reaction of the body to the messenger. Other drugs work using a competitive mechanism to block the action of the body's messenger. Such a drug that prevents the body's own chemical messenger from binding to a receptor site is called an antagonist. It inhibits the natural reaction of the body to the messenger..

[Audio] Drugs that are classified as blockers such as beta-blockers are antagonists. This means beta-blockers prevent stimulation of certain beta-receptors..

[Audio] Medications typically work as agonists or antagonists. An agonist stimulates a receptor site while an antagonist blocks a receptor site to prevent stimulation. This graphic illustrates a receptor site before any drug, with an agonist drug, and with an antagonist drug. Note that before the drug, normal cellular activity occurs. With an agonist drug, there is enhanced cellular activity. With an antagonist drug, cellular activity is blocked..

[Audio] Pharmacokinetics is the study of how the body affects a drug. It involves studying the activity of a drug within the body over a period of time. There are four processes involved in pharmacokinetics: absorption, distribution, metabolism, and elimination. These are referred to as ADME. This figure provides an overview of the pharmacokinetic processes: absorption of drug into bloodstream, distribution of drug to organs and tissues, metabolism of drug by the liver, and elimination of drug in liquid waste by kidney and solid waste by intestine..

[Audio] Absorption is the process by which a drug enters the circulatory system or bloodstream. The absorption of a drug depends on its route of administration, its solubility in blood or other bodily fluids, and other physical properties. Distribution is the process by which a drug moves from the bloodstream into other body fluids and tissues and ultimately to its sites of action. Factors that affect the rate and extent of distribution are blood flow, binding of plasma proteins, binding to cellular constituents, and the blood-brain barrier..

[Audio] Absorption of certain orally administered drugs depends on food. Some drugs are absorbed better by the body on an empty stomach. Others are better absorbed with food. As a pharmacy technician, you can help patients by placing auxiliary labels on drugs that require special attention to food..

[Audio] Metabolism is the process of converting drugs to other biochemical compounds and then excreting them through metabolic pathways. The substance that has been converted through metabolism is call a metabolite. A metabolic pathway is the series of steps involved in the conversion. The liver metabolizes drugs through a system of enzymes called cytochrome P-450. Induction refers to an increase in the amount of enzyme available for metabolism while inhibition refers to a decrease..

[Audio] Elimination is defined as the removal of a drug or its metabolites from the body. It occurs mainly in the kidneys through urine and in the liver through feces. Clearance refers to the rate at which a drug is eliminated from a specific volume of blood per unit of time..

[Audio] Safe and effective drug therapy requires that a drug is delivered to its target sites in concentrations that will treat the disease without producing toxicity. A dose is the quantity of drug administered at one time. A dose may be in measured in milligrams or milliliters. A dosage refers to the specific amount, dose number, and dose frequency of a drug. An example of a dosage is 325 mg every 6 hours. The dose-response relationship of a drug is studied in order to maximize the benefit of the drug and reduce the toxicity. As higher dosages of a drug are given, a greater response will occur. The ceiling effect is the point at which either no greater benefit is seen or toxicities of the drug are greater than its benefits..

[Audio] This figure illustrates the dose-response curve. As greater doses of a drug are given, a greater response is noted until a point is reached when the response no longer improves with increased dosing. This is known as the ceiling effect..

[Audio] When a dose is given, only a portion of it becomes biologically active in the body. Bioavailability is the fraction of a dose available to the target tissue. Drugs taken by mouth must pass through the intestinal wall and the liver before entering the blood and intended sites. Metabolism of a drug in the liver before it reaches the systemic circulation is called the first-pass effect. This may result in reduced bioavailability of some drugs taken by mouth. Oral furosemide is approximately 50% bioavailable. This means that only half of the oral dose is available to the target tissue. Nearly all of a dose of intravenous furosemide is bioavailable. The oral furosemide label shown in the top image is 40 milligrams while the intravenous furosemide label in the bottom image is 20 milligrams. Due to the bioavailability of each dosage form, these doses are roughly equivalent..

[Audio] The therapeutic range is the range of serum concentrations for a drug that provides the optimal probability of achieving the desired response with the least probability of toxicity. A defined therapeutic range provides the best chance for successful therapy. A therapeutic level is the amount of drug in a patient's blood which gives the desired response. A loading dose is an amount of drug that will bring the blood concentration rapidly to a therapeutic level. A maintenance dose is a dose given at regular intervals to keep the drug at a therapeutic level..

[Audio] Pharmacokinetic modeling is a method of mathematically describing the process of absorption, distribution, metabolism, and elimination of a drug within the body. For some drugs, elimination is a zero-order process; that is, a fixed quantity of drug is eliminated per unit of time. The best example is alcohol. For the majority of drugs, elimination is said to be first order; that is, a constant fraction of the remaining drug is eliminated per unit of time..

[Audio] The time it takes the body to eliminate half of such a drug is called the half-life of the drug. A longer half-life implies a longer duration of the drug action. It takes about five to seven half-lives to consider the drug "removed" from the body—meaning that only 1–3% remains. For example, if the half-life of a drug is two hours, then the majority of the drug will be gone in 10 to 14 hours. Or if the half-life is 30 hours, then it will take 150 to 210 hours, or six to nine days, to eliminate most of the drug. A drug with a long half-life may produce effects for days or even weeks after being discontinued..

[Audio] Chapter 1, Section 3, Drug Effects. 1.3 Drug Effects.

[Audio] Pharmacokinetics provide information on predicting the effects of a specific drug. Some effects are beneficial, while other effects can be detrimental. The therapeutic effect is the desired action of a drug or reason for which it is prescribed. Drugs can act locally, or they can act on the body as a whole. A local effect is the effect confined to a specific part of the body. In contrast, a systemic effect is the generalized effect on the entire body..

[Audio] Sometimes drugs are used to prevent an infection or disease. In this case, the drug effect is referred to as prophylaxis. A disease, symptom, or condition for which a drug is beneficial is called its indication. A disease, symptom, or condition for which the drug may be beneficial and may do harm is termed a precaution. Precautions are situations where the benefit of the medication may still outweigh the risks, but the risks need to be further evaluated by the prescriber. A contraindication is when a drug will cause harm and should not be used due to a specific situation..

[Audio] An adverse effect or side effect is a secondary response to a drug other than its intended primary therapeutic effect. The most common side effects are nausea, rash, and constipation. Sometimes drugs are used for their side effects. For example, many antihistamines cause drowsiness, and therefore, they are found in many over-the-counter insomnia preparations..

[Audio] An allergic response is defined as a local or general reaction of the immune system to a substance. A substance that produces an allergic response is called an allergen. In a broader sense, any molecule that stimulates an immune response, whether allergic or not, is known as an antigen..

[Audio] Common allergic reactions include nasal secretions, swelling, wheezing, rapid heart rate, urticaria as shown in the image on this slide, pruritis, angioedema, and wheals..

[Audio] An anaphylactic reaction is a severe allergic response resulting in immediate, life-threatening respiratory distress, usually followed by vascular collapse and shock accompanied by hives. An idiosyncratic reaction is an unusual or unexpected response to a drug that is unrelated to the dose given..

[Audio] Drug dependence is a state in which a person's body adapts physiologically and psychologically to a drug and cannot function without it. Dependence should not be confused with addiction which is a dependence characterized by a perceived need to use a drug for its mood-altering effects. Patients who are being treated for various disease states may become dependent on medications without exhibiting the signs of addiction. Drug abuse is the use of a drug for purposes other than those prescribed and/or in amounts not directed. Abusive use of drugs can be, but is not always, linked to addiction. Tolerance is a decrease in response to the effects of a drug with continued administration..

[Audio] A drug interaction is a change in the action of a drug that is caused by another drug, a food, or a substance. Common mechanisms for interactions include inducing or inhibiting enzymes that metabolize the drug. For example, grapefruit and grapefruit juice interfere with proper absorption of several common drugs. In this instance, less of the drug undergoes first-pass metabolism, resulting in more active drug absorbed into the bloodstream..

[Audio] It is important that prescribers and pharmacists have a complete list of all prescription drugs, OTC medications, vitamins, and herbal remedies that a patient is taking so that potential interactions can be recognized and appropriately handled. The pharmacy technician should routinely ask for this information. Table 1.2 lists common drug relationships, including addition, antagonism, potentiation, and synergism..

[Audio] Chapter 1, Section 4, Complementary and Alternative Medicine.

[Audio] Alternative medicine describes medical products and practices that are not part of standard care and that are used in place of conventional practice. An example of alternative medicine could be using acupuncture to treat back pain from a muscle spasm. Complementary medicine employs similar methods to alternative medicine but is used together with conventional practices. An example of complementary medicine could be using acupuncture as well as a muscle relaxant medication to treat back pain from a muscle spasm..

[Audio] More than 40% of Americans admit to using complementary and alternative medicine, or CAM. Reasons for popularity include greater availability of information on the internet, increased contact with cultures that use alternative medicine, perceptions of greater safety, and distrust of conventional medicine. CAM is a widespread practice but there are some concerns about its use. First, there is limited scientific evidence regarding safety and efficacy. Second, there is a lack of training, knowledge, and confidence in CAM among healthcare providers. Third, there is a frequent lack of disclosure by patients who use CAM. This omission may be dangerous because interactions can occur between CAM and prescribed drugs..

[Audio] A dietary supplement describes a category of nonprescription drugs that includes vitamins, minerals, and herbs. Supplements exert weak pharmacological effects. Pharmacy technicians should be aware that dietary supplements do not have the same stringent controls as prescription medications. They are not regulated by the FDA unless safety concerns exist, and the quality of some products is questionable. Pharmacy technicians can help patients avoid adverse reactions by gathering and recording information about their use of these products..

[Audio] Patients may ask technicians working in the community pharmacy setting to help them find herbal supplements. Try to familiarize yourself with how supplements and herbs are organized. Sometimes they are arranged alphabetically, and other times they are arranged by body system..

[Audio] Homeopathic products contain subclinical doses of natural extracts or alcohol tinctures in which the active ingredient is diluted. These small doses are thought to stimulate the body's immune system to overcome symptoms when sick. These products are available over the counter and patients may seek their use to treat cold symptoms, headaches, and indigestion. It is important to understand that homeopathic products are marketed without the FDA evaluating them for safety or effectiveness..