Pharmacology for Pharmacy Technicians. Pharmacology. Pharmacology, cont'd. Fundamentals of Pharmacology

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1 Pharmacology for Pharmacy Technicians Fundamentals of Pharmacology Pharmacology Pharmacy technicians have the skills to refill a prescription based on the patient s profile. Pharmacy technicians have good knowledge of drug names and can avoid drug look-alike/sound-alike issues. Study of drugs and their interactions with living systems, including: Chemical and physical properties (Chemical properties of the drug influence absorption, distribution, metabolism, and elimination of the drug in the body.) Toxicology Therapeutics 2 Pharmacology, cont'd Therapeutic duplication can include nonprescription drugs and supplements. Pharmacy technicians can recognize incorrect drugs, strengths, and dosages. Pharmacy technicians must have knowledge of pharmacology Properly identify drug from patient s profile Spend less time searching for drugs Reduce dispensing errors Select proper warning labels Recognize possible drug interactions, therapeutic duplication, excessive doses 3

2 History of Medicines and Their Use Plants used for millennia to treat illness Records from Egypt, Mesopotamia, India, China Greek physician Theophratus, father of pharmacology Dioscorides, Greek physician, described medicinal plants Plants have been used to treat illness for thousands of years. Dioscorides described the use of aloe, belladonna, ergot, and opium. What is the humoral theory? (This theory was put forth by Galen, the father of pharmacotherapy, and it states that illness is caused by an imbalance of humors and is treated with Simples, Composites, and Entities.) 4 History of Medicines and Their Use, cont'd Twentieth century: exponential growth Antiinfective agents Insulin Antiretroviral drugs Human Genome Project Genetically modified drugs Bioengineering Banting and Best discovered that insulin reduces blood sugar levels. What are some other advances that were made in the early twentieth century? What is the Human Genome Project? (The Human Genome Project, a study of human genes, has provided data useful in understanding diseases that are caused by genetic defects or linked to heredity. The study of genes has also enabled scientists to develop new genetically modified drugs, such as human insulin.) Erythropoietin and human insulin are two examples of biopharmaceuticals. 5 Origin of Drugs Pharmacognosy is the study of the natural origin of drugs. The aim of drug therapy is to diagnose, treat, cure, or lessen the symptoms of disease. Pharmacognosy: study of natural origin of drugs Drug affects normal structure or function of humans or animals Drug may be used to: Diagnose Treat Mitigate Cure Prevent disease 6

3 Origin of Drugs, cont'd Synthetic drugs may be: Chemical modification of natural drug Manufactured entirely from chemical ingredients Manufactured via bioengineering What are some drugs found in common foods and drinks? (Coffee and tea contain the drug caffeine. Ginger and peppermint contain ingredients that can reduce nausea.) Some common beverages and foods are natural drugs. Coffee and tea contain the drug caffeine. Ginger and peppermint contain ingredients that can reduce nausea. 7 What Is Pharmacology? Study of actions of drugs on humans and animals Combines study of: Properties of drugs Mechanism of drug action Anatomy and physiology Pathology Pharmacy technicians have the skills to refill a prescription based on the patient s profile. Pharmacy technicians have good knowledge of drug names and can avoid drug look-alike/sound-alike issues. Knowledge of pharmacology facilitates selection of warning labels for drugs dispensed. Pharmacy technicians who possess a good knowledge of pharmacology understand the importance of recognizing drug interactions, therapeutic duplication, and excessive dose alerts screened by the computer. 8 What Is Pharmacology?, cont'd Therapeutic duplication can include nonprescription drugs and supplements. Pharmacy technicians can recognize incorrect drugs, strengths, and dosages. Pharmacology enables: Selection of appropriate drug for patient Proper dose and dosage form Appropriate dosing schedule 9

4 Research and Development Pure Food and Drug Act (1906) Expanded in 1938 Sets standards for allowing new drugs onto market It can take several years to move a new drug from the idea phase to making it available to the public. In 1906, the Pure Food and Drug Act was passed to protect the public from ineffective and harmful drugs. This Act was expanded in 1938, and standards for allowing new drugs onto the market were set. 10 Research and Development, cont'd Steps in drug development process Preclinical research Clinical studies New drug application process Review Manufacturers of new drugs must show that their drug is reasonably safe before small-scale clinical trials can begin. There are many steps in the drug development process. The steps from the test tube to production and distribution of a new drug involve preclinical research, clinical studies, a new drug application process, and review. 11 Research and Development, cont'd Three clinical study phases Phase 1: Drug administered to small group of healthy volunteers Phase 2: Controlled trials with patients who have condition to be treated Phase 3: Hundreds to a few thousand patients Trials in phase 3 involve many more patients. In phase 1 clinical trials, the drug is administered to a small number of healthy volunteers who are enrolled in the clinical study. Preliminary information about the drug s pharmacology, mechanism of action, and effectiveness in humans in a controlled clinical trial (efficacy) is gathered in phase 1. Phase 2 studies are controlled trials with a limited number of patients with the condition to be treated. During this phase, data are collected to determine the drug s efficacy and the drug s side effects in patients with the disease. 12

5 Research and Development, cont'd Prescription Drug User Fees Act (1992) Pay fee to USDA for faster review Food and Drug Amendments Act (2007) User fees can be used for risk management and communication Pharmacovigilance encouraged Set guidelines for postmarket* clinical studies The FDA Amendments Act increased the FDA s responsibility to adopt a more proactive approach to pharmacovigilance. Additional safety information is collected in the postmarketing phase. Phase 4 trials are studies that are conducted after the drug is marketed to the public to determine safety and effectiveness when the drug is used in real-world conditions. 13 Research and Development, cont'd What are some similarities between the Canadian and U.S. systems for drug approval? (Both countries require regulation for drug approval and marketing of new drugs. Preclinical and phase I to IV clinical studies are also required in both countries.) In Canada: Therapeutic Products Directorate approves prescription drugs Marketed Health Products Directorate responsible for postmarket safety Preclinical and phase I-IV studies also required 14 Drug Nomenclature Brand name or proprietary drugs are commonly written beginning with a capital letter, and generic or nonproprietary drugs begin with a lowercase letter. All drugs identified by: Generic name Chemical name Proprietary name (The proprietary name or brand name is assigned by the drug manufacturer according to nomenclature guidelines and must be approved by the CDER.) 15

6 Drug Nomenclature, cont'd Center for Drug Evaluation and Research Sets standards for new names U.S. Adopted Name (USAN) Council Selects nonproprietary names Must be approved by FDA Why are standards necessary in the naming of new drugs? (The USAN Council has several criteria for a generic name. The name must be appropriate for the drug; short, easy to pronounce, and euphonic; and suitable for routine use both in the United States and internationally. The name cannot be misleading or confusing or imply efficacy or application to particular anatomical parts. The USAN Council also attempts to minimize similarities with other drug names.) 16 Drug Nomenclature, cont'd What are some of the benefits of having a common ending for a pharmacological class of drugs? (The ending of the official name of many drugs indicates the pharmacological class to which the drug belongs. For example, many local anesthetics have the common ending -caine".) Ending of official name may indicate: Pharmacological class of drug 17 Drug Nomenclature, cont'd The chemical structure of the drug determines its activity and side effects. Proprietary names usually are shorter and easier to remember than chemical names and generic names. Proprietary names often contain a portion of the generic name. Generic name: Nonproprietary name commonly used to identify drug Chemical name: Describes molecular structure of drug Proprietary/brand name: Assigned by the manufacturer according to guidelines Must avoid look-alike and sound-alike risks 18

7 Comparisons Between Brand Name and Generic Drugs In many states, pharmacists routinely dispense generic drugs. Manufacturer of new drug May apply for patent If awarded, patent gives exclusive right to new drug for 20 years Selects brand name according to CDER guidelines 19 Comparisons Between Brand Name and Generic Drugs, cont'd What are some drugs that have recently gone off patent and become available in generic form? (Plavix, Lipitor, Levaquin, Singulair) When patent ends, other manufacturers may produce generic version Generic drug: Contains same active ingredients as original drug May contain different inactive ingredients Can receive A rating from FDA if not significantly different from original drug Always less expensive than brand name drugs 20 Drug Legislation Pure Food and Drug Act (1906) First significant legislation Protect public from harmful and ineffective drugs Durham-Humphrey Amendment (1951) Legend drugs OTC drugs What kinds of drugs were being sold and used before the Pure Food and Drug Act? (The Pure Food and Drug Act required that certain special drugs, including alcohol, cocaine, heroin, morphine, and cannabis, be accurately labeled with contents and dosage. Previously many drugs had been sold as patent medicines with secret ingredients or misleading labels. Cocaine, heroin, cannabis, and other such drugs continued to be legally available without prescription as long as they were labeled.) 21

8 Legend drugs can be obtained only with a prescription. Drug Legislation, cont'd Kefauver-Harris Amendment (1962) requires drugs to be: Safe Effective Drug Price Competition Act and Patent Restoration Act (1984) Encouraged development of generic drugs Behind-the-counter (BTC) drugs Transition between legend and OTC status No prescription required but access limited 22 Drug Legislation, cont'd Combat Methamphetamine Act of 2005 (CMEA) To combat illegal manufacture of crystal meth Regulates retail sales of methamphetamine ingredients Comprehensive Drug Abuse Prevention and Control Act (a.k.a/ Controlled Substance Act (CSA) (1970) Regulates drugs with history of abuse Categories C-I through C-V Controlled Drug and Substances Act in Canada What are some of the required provisions of the CMEA? (Purchase limits, placement of product out of direct customer access, sales logbooks, customer ID verification, and employee training) The CMEA of 2005 was passed to curb the illegal manufacture and use of crystal meth. The CMEA was signed into law on March 6, 2006, to regulate, among other things, retail over-the-counter sales of ephedrine, pseudoephedrine, and phenylpropanolamine products used to manufacture crystal meth. Purchase limits, placement of product out of direct customer access, sales logbooks, customer ID verification, employee training, and selfcertification of regulated sellers are required provisions of the CMEA. The Combat Methamphetamine Epidemic Act of 2005 (CMEA) was signed into law on March 6, 2006, to regulate, among other things, retail over-the-counter sales of ephedrine, pseudoephedrine, and phenylpropanolamine products. Purchase limits, placement of product out of direct customer access, sales logbooks, customer ID verification, employee training, and self-certification of regulated sellers are required provisions of the CMEA. 23 Drug Dosage Forms and Delivery Systems Chemical properties of the drug influence absorption, distribution, metabolism, and elimination of the drug in the body. Drugs formulated for delivery by: Mouth (oral) Injection (parenteral) Inhalation Topical application to skin or mucous membrane 24

9 Drug Dosage Forms and Delivery Systems, cont'd How can normal physiological processes affect the choice of drug formulation? (For example, drugs formulated for transdermal administration must have sufficient lipid solubility to enable the drug to pass through the cell membranes of skin and get to the site of action.) Factors affecting choice of drug formulation Chemical properties of drug Human physiology 25 Dosage Forms for Oral (Enteral) Administration Repeat-action tablets are layered. Delayed-action tablets slow the release of the drug. Enteric-coated tablets release their contents in the small intestine. Tablets Repeat action Delayed action Enteric coated Sustained release and time release Film coating and sugar coating 26 Dosage Forms for Oral (Enteral) Administration, cont'd Tablets, cont'd Chewable Sublingual Oral disintegrating (ODTs) Troches and lozenges Thin film Chewable tablets are formulated for people who have difficulty swallowing pills. Many children s medicines are available in a chewable dosage form. Sublingual tablets and buccal tablets dissolve in the mouth. ODTs are similar to sublingual tablets, but they disintegrate more rapidly (in < 60 seconds). 27

10 Dosage Forms for Oral (Enteral) Administration, cont'd Capsules can be formulated to release their contents immediately or over time. Suspensions contain small drug particles suspended in a solvent. Syrups contain a high concentration of a sugar. Elixirs and tinctures contain alcohol. Capsules Oral liquids Suspensions Syrups Elixirs Tinctures Emulsions 28 Dosage Forms for Topical Administration Ointments can soften dry, scaly skin. Suppositories melt at body temperature. Transdermal patches are used to treat angina, male hypogonadism, menopause, and pain. Ointments Creams Hydrogels Suppositories Transdermal drug delivery systems (patches) 29 Dosage Forms for Parenteral Administration Parenteral administration avoids the reduction in drug level that results from administration through the gastrointestinal tract. Parenteral drugs are injected or infused (slowly injected) directly into a blood vessel, muscle, skin, or joint. Parenterally administered drugs enter the bloodstream, producing rapid action. Injected or infused directly into: Blood vessel Muscle Skin Joint Enter the bloodstream, producing rapid action 30

11 Dosage Forms for Parenteral Administration, cont'd Why does a pharmacy technician have to use aseptic technique in a sterile environment when preparing parenteral drugs? (To avoid introducing contaminants that are harmful if injected into a patient) Because of rapid, often irreversible action, pharmacy technician must prepare: Using aseptic technique In a sterile environment 31 Dosage Forms for Parenteral Administration, cont'd What is an example of an intradermal solution? (allergy tests or tuberculosis vaccinations) Examples of parenteral forms: Intravenous (IV) solutions Intramuscular (IM) solutions Subcutaneous (SC) solutions and suspensions Intraarticular solutions Intradermal solutions Intrathecal solutions 32 Dosage Forms for Respiratory Tract Administration Inhalation is a method of delivering a drug rapidly into the general circulation. Solutions and suspensions applied to mucous membranes of nose Micro-fine powders, solutions, gaseous drugs inhaled into lungs using: Metered dose aerosol inhaler Nebulizer 33

12 Routes of Administration Drugs such as penicillin and insulin can be reduced significantly by acids and enzymes in the GI tract. Route of administration is determined by drug dosage form If more than one route available, choice determined by: Drug properties Ease of administration Pathophysiology Therapeutic objectives 34 Drugs that are administered parenterally bypass the GI tract. Routes of Administration, cont'd Major routes of administration Enteral (oral) Parenteral (IV, IM, SC) Inhalation Topical 35 The parenteral route produces a rapid onset of action. Routes of Administration, cont'd Enteral, parenteral, inhalation produce systemic effects Extend beyond area of drug application Topical drugs produce local effects 36

13 Routes of Administration, cont'd No special techniques are required for administration of enteral drugs. A drug administered enterally can be recalled via vomiting or binding with activated charcoal if needed. An advantage to parenteral administration is rapid onset of action. Enteral advantages Safe and easy compared with parenteral Drug can be removed if necessary Generally less expensive than parenteral 37 Routes of Administration, cont'd What is bioavailabilitiy? (Bioavailability is the fraction of the administered drug dose that enters the systemic circulation and is available to produce drug effect.) Enteral disadvantages Variable absorption Lower bioavailability First-pass effect via liver Reduction via stomach acids 38 Routes of Administration, cont'd What types of patients are candidates for the parenteral route of administration? (Parenteral administration is preferred when the patient is unable to swallow [e.g., unconscious] or is experiencing nausea and vomiting.) Parenteral When drug is poorly absorbed via oral route Avoids degradation by GI tract and liver Greater bioavailability Rapid onset of action Dosage can be carefully controlled 39

14 Routes of Administration, cont'd Drugs administered parenterally directly enter the general circulation and cannot be easily recalled. Parenteral Aseptic technique required during preparation After administration, cannot be recalled via vomiting Administration requires special techniques 40 This method also avoids the drawbacks of enteral administration. Routes of Administration, cont'd Inhalation Effective method of delivering drug to respiratory tract and general circulation Avoids problems of oral administration Effective in treatment of respiratory disorders Used for administration of some anesthesia drugs 41 Routes of Administration, cont'd Several systemic drugs can be administered transdermally. Topical formulations are intended to produce only a local effect. Transdermal Applied to skin to produce systemic effects May produce systemic and local side effects 42

15 Local side effects such as skin irritation are possible. Routes of Administration, cont'd Topical Often intended for local effect only (nitroglycerin is exception) Avoids systemic side effects of oral administration Side effects are usually local 43