Unit 1 Introduction to Pharmacology PDF

Diploma in Healthcare Write an optional subtitle here Please do not reproduce, redistribute or share without the prior express permission of the author. Introduction to Pharmacology Unit 1: Introduction to Pharmacology Please do not reproduce, redistribute or share without the prior express permissi...

Diploma in Healthcare Write an optional subtitle here Please do not reproduce, redistribute or share without the prior express permission of the author. Introduction to Pharmacology Unit 1: Introduction to Pharmacology Please do not reproduce, redistribute or share without the prior express permission of the author. Topic/Chapter Learning Outcome Identify the concept of pharmacy. Define key terms used in pharmacology. Distinguish between pharmacology and pharmaceutics. Acquire knowledge about drug and its effects. Able to differentiate types of drugs. Gain basic knowledge on prescriptions. Please do not reproduce, redistribute or share without the prior express permission of the author. Topic and Structure of the lesson Introduction to Pharmacology Pharmaceutical Preparation Route of Drug Administration Principles of Drug Action Mathematics of Drug Dosage Please do not reproduce, redistribute or share without the prior express permission of the author. PHARMACY Pharmacy is a location where prescription drugs are sold. PHARMACIST Pharmacists are person familiar with medication ingredients, interactions, cautions and hints. Pharmacists are thus trained to prepare and distribute medicines and to give information about them. Please do not reproduce, redistribute or share without the prior express permission of the author. PHARMACOLOGY Pharmacology is a study of substances (drug) that interact with living systems through chemical processes. PHARMACOLOGIST Pharmacologist is the person who study the pharmacology of the drugs. Please do not reproduce, redistribute or share without the prior express permission of the author. COMPONENT IN PHARMACOLOGY Pharmacokinetics refers to activities within the body after a drug is administered. These activities include absorption, distribution, metabolism and excretion Pharmacodynamics refers to drug’s action and effect within the body. Please do not reproduce, redistribute or share without the prior express permission of the author. PHARMACEUTICS The science of preparing and dispensing drugs. Pharmaceutics is the science of dosage form design. Pharmaceutics deals with the formulation of a pure drug substance into a dosage form. Please do not reproduce, redistribute or share without the prior express permission of the author. DRUG Any substances that brings a change in biology function through its chemical actions. Majority drug molecules interact with a receptor. Very small number of drug (chemical antagonist) may interact directly with other drugs. APH 1212 –1.1 / S 7 Please do not reproduce, redistribute or share without the prior express permission of the author. DRUG SOURCES Drug may be synthesized within the body (hormones) or it may be chemicals (xenobiotics). Types of drugs are: Animal origin Plant origin Microbial origin Now, drugs are also produced by: Direct chemical synthesis Genetic engineering (biotechnology) Please do not reproduce, redistribute or share without the prior express permission of the author. Drugs and its Sources PENICILLIN MORPHINE Papaver somniferum (opium poppy) Penicillium notatum INSULIN Sus scrofa scrofa (western Africa, Europe), Sus scrofa ussuricus (northern Asia ) (Porcine pancreatic tissue ) Please do not reproduce, redistribute or share without the prior express permission of the author. Biotechnology application Associated to the use of genetically altered microorganisms such as E. coli or yeast for producing substances like insulin or antibiotics. APH 1212 –1.1 / S 10 Please do not reproduce, redistribute or share without the prior express permission of the author. DRUG NOMENCLATURE Refers to naming of the drug. 1. Chemical name Represent s the exact chemical structure of the drug (not capitalized). 2. Generic (non-proprietary) name The name which chosen by the official agencies e.g WHO (not capitalized) 3. Trade or brand (proprietary) name The name that given by the manufacturer. (first letter capitalized). Please do not reproduce, redistribute or share without the prior express permission of the author. EXAMPLE: Chemical name: ethyl 4-(8-chloro-5,6-dihydro- 11H-benzo[5,6]cycloheptal[1,2b] -pyridin-11- ylidene)-1-piperidinecardisplayylate Generic (nonproprietary) name: loratadine Trade (brand) name: Claritin© Please do not reproduce, redistribute or share without the prior express permission of the author. EXAMPLE: Chemical name: n(4-hydroxyphenyl)acetamide Generic (nonproprietary) name: paracetamol or acetaminophen Trade (brand) name: Panadol, Calpol, Adol Please do not reproduce, redistribute or share without the prior express permission of the author. DRUG REACTIONS Drug produce many reaction in the body, such as: Adverse drug Reactions Undesirable drug effects Occur after first dose, after several doses or even after many doses Side effects - explain mild, common and nontoxic reactions Adverse effect - describe more severe and life- threatening reactions Please do not reproduce, redistribute or share without the prior express permission of the author. Allergic Drug Reactions Also called hypersensitivity reaction. Occur after more than one dose of the drug. Body’s immune system recognize the drug as a foreign material or antigen. Presence of antigen stimulates the antigen- antibody response to produce antibodies. Please do not reproduce, redistribute or share without the prior express permission of the author. Drug Tolerance Decreased response to a drug. Require an increase dosage to achieve the desired effect. Develops when a patient takes certain drugs (narcotics and tranquilizers) for a long time. May also occur in the hospitalized patient (receives narcotics for more than 10 to 14 days). Please do not reproduce, redistribute or share without the prior express permission of the author. Toxic Reactions Occur when drug administered in a large dosages or when blood concentration levels exceed the therapeutic level. Some toxic effects are immediately visible; others may not seen for weeks or months. Can be reversible or irreversible, depending on the organs involved. Please do not reproduce, redistribute or share without the prior express permission of the author. FACTORS INFLUENCING DRUG RESPONSE Certain factors may influence drug response These factors include: Age Body weight Gender Disease Genetics Route of administration Please do not reproduce, redistribute or share without the prior express permission of the author. DRUG CATEGORIES 1) Prescription Drugs (Legend drug) Largest category of drug Harmful unless used under supervision. Although these drugs have been tested for safety and therapeutic effect, prescription drugs may cause different reactions in some individuals. Please do not reproduce, redistribute or share without the prior express permission of the author. 2) Non-prescription Drugs Designated to be safe (if taken as directed). Can be obtained without prescription. Also known as over-the-counter (OTC) drugs. There are risk and may produce adverse reactions. Consumers are urged to read the directions carefully before taking OTC drugs Please do not reproduce, redistribute or share without the prior express permission of the author. 3) Controlled Substances Most carefully monitored drugs. Have high potential for abuse and may cause physical or psychological dependence. Prescription must be written in ink and include name and address of the patient and Drug Enforcement Agency number of primary health care provider. Please do not reproduce, redistribute or share without the prior express permission of the author. PRESCRIPTION Legal document contains written instructions from physician for pharmacist or pharmacy assistant to dispense drug. The prescription contains the name of the drug, the dosage, the method and times of administration and the signature of the licensed health care provider prescribing the drug. Please do not reproduce, redistribute or share without the prior express permission of the author. Five Parts of Prescription 1. 2. 3. 4. 5. Superscription- Name, date, patient’s address Inscription- Main body: drug name / strength Subscription- How much drug to dispense Transcription How to take medication Signature- Doctor’s signature Professional degree DEA, for controlled drug Please do not reproduce, redistribute or share without the prior express permission of the author. Sample Of Prescriptions Please do not reproduce, redistribute or share without the prior express permission of the author. 1.2 Pharmaceutical Preparation Please do not reproduce, redistribute or share without the prior express permission of the author. OBJECTIVES At the end of the lesson, students should be able to: Define dosage form. Classify dosage forms. Describe each type of dosage form. Please do not reproduce, redistribute or share without the prior express permission of the author. DOSAGE FORM Dosage form is a system or device for delivering drug to the biological system. A dosage form consist of an active ingredient (drug) in inactive material. Please do not reproduce, redistribute or share without the prior express permission of the author. TYPE OF DOSAGE FORM Dosage form can be classified as A. Solid dosage form B. Semisolid dosage form C. Liquid dosage form D. Sterile dosage form E. Miscellaneous dosage form Please do not reproduce, redistribute or share without the prior express permission of the author. A. Solid Dosage Form 1.Tablets 2. Capsules 4. Powder 3. Lozenges 5. Caplets Please do not reproduce, redistribute or share without the prior express permission of the author. 1. Tablet Tablets are solid dosage forms that are compacted into small, formed shapes. Tablet contain active ingredient and inactive ingredient. Can be made by moulding or compression method. Please do not reproduce, redistribute or share without the prior express permission of the author. 2. Capsule Capsules are solid dosage form in which the drug is enclosed in a practically tasteless, hard or soft soluble container or shell made up of a suitable form of gelatin. There are two type gelatin: Type A – Derived from acid hydrolysis of collagen. It is manufactured mainly from pork skin Type B – Derived from alkali hydrolysis of collagen. It is manufactured mainly from animal bone Please do not reproduce, redistribute or share without the prior express permission of the author. 3. Lozenges These are hard disk shaped dosage forms which contain a sugar base, also known as pastilles or troches. Used to deliver the medication to the patient’s mouth or throat. Please do not reproduce, redistribute or share without the prior express permission of the author. 4. Powder Bulk powders for internal use (oral) Eg. Potassium Chloride powder Bulk powder for external use (dusting powder) Eg. Daktarin powder 5. Caplet A smooth, coated, oval-shaped medicine tablet intended to be tamper-resistant. Please do not reproduce, redistribute or share without the prior express permission of the author. B. Semi-solid Dosage Form Suppositories Ointment Cream Please do not reproduce, redistribute or share without the prior express permission of the author. 1. Suppositories Semi-solid dosage forms intended for the application of medication to any of several body cavities, namely rectum, vagina or urethra. 2. Ointment Ointments are semisolid dosage forms made of solid and liquid medications. Please do not reproduce, redistribute or share without the prior express permission of the author. 3. Cream Creams are semi-solid emulsions that is mixtures of oil and water. They are divided into two types: i. Oil-in-water (O/W) - small droplets of oil dispersed in water base ii. Water-in-oil (W/O) - small droplets of water dispersed in oily base Please do not reproduce, redistribute or share without the prior express permission of the author. C. Liquid Dosage Form Solution Liniments Emulsions Suspension Extractives Please do not reproduce, redistribute or share without the prior express permission of the author. 1. Solution These are dosage form in which the medication is completely dissolved and evenly distributed in a homogenous mixture. 2. Liniments Are medications that are applied to the skin with friction and rubbing. 3. Emulsions A biphasic liquid preparation containing two immiscible liquids, one of which is dispersed as minute globules in another. Please do not reproduce, redistribute or share without the prior express permission of the author. 4. Suspensions It consists of a two phase system in which the internal phase is solid and the external phase is liquid. The internal phase (solid) is dispersed throughout the external phase (fluid) through mechanical agitation, with the use of certain excipients or suspending agents. Magmas and milks are suspensions of medications in water. They are very thick ,viscous liquids 5. Extractives. Medications derived from plant or animal tissue. These liquid mixtures are made from concentrated active ingredients obtained from plant and animals. Tinctures Fluid extracts Extracts. Please do not reproduce, redistribute or share without the prior express permission of the author. D. Sterile preparations Injection Eye Drop Ear Drop Medicine that are sterile and free from microorganism Please do not reproduce, redistribute or share without the prior express permission of the author. E. Miscellaneous 1. Inhalations or aerosols. Medications are packed in high pressure and when expelled produce very fine particles. 2. Trans-dermal Patch Medications are incorporated in adhesive plasters and placed in the skin. Drug will be slowly absorbed to the body through the dermis. Please do not reproduce, redistribute or share without the prior express permission of the author. 1.3 Route of Drug Administration Please do not reproduce, redistribute or share without the prior express permission of the author. OBJECTIVES At the end of the lesson, students should be able to: 1. Identify the route of drug administration. 2. Identify the method of enteral drug administration. 3. Identify the methods of parental drug administration. 4. Identify the abbreviations used in parental drug administration. 5. Identify the methods of drug administration through skin and mucous membrane. Please do not reproduce, redistribute or share without the prior express permission of the author. Route of Administration Route of administration is the path by which a drug Is brought into contact with the body. Main route of drug administration: „ Enteral - through digestive tract „ Parental - through injections „ Skin and mucous membrane Please do not reproduce, redistribute or share without the prior express permission of the author. 1. ENTERAL Drugs enters the body either by mouth or rectum (Gastro-Intestinal Tract). This route of administration produces systemic action. ROUTE DESCRIPTION NOTES Oral By mouth Tablet, Capsule Buccal Across the membrane of the mouth (cheeks) Tablets Sublingual Under the tongue Tablets Rectal - Suppositories, Enema Please do not reproduce, redistribute or share without the prior express permission of the author. 2. PARENTAL Drugs are given through injections. It produces desired systemic effects. Please do not reproduce, redistribute or share without the prior express permission of the author. TYPES OF INJECTION Intravenous (IV) Intramuscular (IM) Subcutaneous (SC) Intradermal (ID) ADMINISTRATION INFO NOTES Vein Muscle (upper arm, shoulder, thigh, hip) 50- 100ml 1ml-3ml Insert needle at 90⁰ angle Subcutaneous tissue < 1ml (upper arm, upper Insert needle at abdomen, upper back) 45⁰ angle Under epidermis < 0.1ml Into dermis (front Insert needle at forearm) 15⁰ angle Please do not reproduce, redistribute or share without the prior express permission of the author. 3. SKIN AND MUCOUS MEMBRANE Drugs may applied to the skin and mucous membrane using several routes: i. Topical - on outer layer of skin. ii. Transdermal - through a patch on which the drug has been implanted iii. Inhalation - through the membranes of the upper respiratory tract. Please do not reproduce, redistribute or share without the prior express permission of the author. i. Topical route Most topical drugs act on the skin but are not the skin. Used to soften, disinfectant or lubricate the skin. absorbed through ii. Transdermal route The drug dosages are implanted in a small patch- type bandage. The patch is applied to the skin where the drug is gradually absorbed into the systemic circulation. Please do not reproduce, redistribute or share without the prior express permission of the author. iii. Inhalation Drug droplets, vapor or gas are administered through the mucous membranes of respiratory tract with the use of: Nebulizer Positive-pressure breathing machine Examples of drugs; bronchodilators and mucolytics Please do not reproduce, redistribute or share without the prior express permission of the author. Factors that determine ROA 1. Physical and chemical properties of the drug like solid state, PH , solubility, irritability. 2. Rate and extent of absorption. 3. Effect of digestive juices 5. Accuracy of dosage desired 6. Patient’s age 7. Gender 8. Patient’s physical state - conscious / unconscious 9. Patient’s health condition. 10. Cost 11. Site of desired action - localized or systemic Please do not reproduce, redistribute or share without the prior express permission of the author. 1.4 Principles of Drug Action Please do not reproduce, redistribute or share without the prior express permission of the author. OBJECTIVES At the end of the lesson, students should be able to: 1. 2. 3. 4. Define the concept of pharmaceutic phase. Identify the concept of pharmacokinetic phase. Understand the component in pharmacokinetic (ADME). Define pharmacologic terms used in the mechanism of drug action. 5. Able to differentiate between agonist and antagonist. 6. Identify the concept of pharmacodynamic phase. 7. Understand the concept of pharmacodynamic(receptor theory). Please do not reproduce, redistribute or share without the prior express permission of the author. Drug Activity within the Body Oral drugs go through three phases: 1. Pharmaceutic phase 2. Pharmacokinetic phase 3. Pharmacodynamic phase Liquid and parental drugs go through two phases: 1. Pharmacokinetic phase 2. Pharmacodynamic phase Please do not reproduce, redistribute or share without the prior express permission of the author. MECHANISM OF DRUG ACTION PHARMACEUTIC PHASE Enteral Parental Topical and associated membrane PHARMACOKINETIC PHASE Absorption Distribution Metabolism Excretion PHARMACODYNAMIC PHASE Efficacy Potency Please do not reproduce, redistribute or share without the prior express permission of the author. PHARMACEUTIC PHASE Pharmaceutic of drug is the dissolution of the drug. Drug must be in solution to be absorbed. A tablet or capsule will disintegrates into smaller particles and dissolves into the body fluid in GIT. Tablets that are enteric-coated do not disintegrate until it reaches an alkaline environment in the small intestine. Please do not reproduce, redistribute or share without the prior express permission of the author. PHARMACOKINETIC PHASE Pharmacokinetic is an activities within the body after a drug is administered. These activities include (ADME):  Absorption  Distribution  Metabolism  Excretion Please do not reproduce, redistribute or share without the prior express permission of the author. 1. ABSORPTION Absorption is a process by which a drug is made available for use in the body. The drug particles within the gastrointestinal tract are moved into the body fluids. Intravenous administration has no absorption. Please do not reproduce, redistribute or share without the prior express permission of the author. 2. DISTRIBUTION Distribution is a process by which the drugs are distributed by systemic circulation to various body tissues. Please do not reproduce, redistribute or share without the prior express permission of the author. 3. METABOLISM Metabolism also called biotransformation. Metabolism is a process by which a drug is converted by the liver from an active to an inactive compounds. Major site for drug metabolism is liver Kidneys, lungs, plasma and intestinal mucosa also aid in drug metabolism. Please do not reproduce, redistribute or share without the prior express permission of the author. 4. EXCRETION Excretion is process to eliminate drugs from the body. Kidney is the major site to excrete majority of inactive compound (drugs) from the body. Other drugs eliminated by sweat, breast milk, breath or gastrointestinal tract. Please do not reproduce, redistribute or share without the prior express permission of the author. Half-life Half-life is the time required for the body to eliminate 50% of the drug. Drug with a short half-life (2 - 4 hours) need to be administered frequently Drugs with a long half-life (21 - 24 hours) requires less frequent dosing. Difficulty in excreting a drug increases the half-life and increase the risk of toxicity. Please do not reproduce, redistribute or share without the prior express permission of the author. Key Terms in Pharmacodynamics Agonist - are drugs that bind with a receptor to produce a therapeutic response. Antagonist - binds with a receptor to prevent the action of agonist and produce no pharmacologic effect Please do not reproduce, redistribute or share without the prior express permission of the author. How our body function? All body functions are mediated by control systems which depend on : Enzymes Receptors on cell surfaces, carrier molecules Specific macromolecules (DNA). Most drugs act by interfering with these control systems at a molecular level. Please do not reproduce, redistribute or share without the prior express permission of the author. PHARMACODYNAMIC PHASE Pharmacodynamics deals with the drug’s action and effect within the body. After administration of a drug, almost all body tissues exposed to possible effects of the drug. All drugs produce more than one effect in the body. There are two main mechanism of action of drug: 1. Alteration in cellular environment 2. Alteration in cellular function Please do not reproduce, redistribute or share without the prior express permission of the author. 1. Alteration in Cellular Environment Some drugs act by changing the cellular environment Physical changes: Changes in osmotic pressures or absorption. Chemical changes: Inactivation of cellular functions or changes in pH Please do not reproduce, redistribute or share without the prior express permission of the author. 2. Alteration in Cellular Function Most drug act by altering cellular function. A drug cannot completely change the function of a cell, but it can alter its function. A drug that alter cellular function can increase or decrease certain physiologic functions, such as Increase heart rate Decrease blood pressure Increase urine output Please do not reproduce, redistribute or share without the prior express permission of the author. Receptor-Mediated Drug Action The function of a cell alters when a drug interacts with a receptor cell. Receptor are found on cellular membranes or in the nucleus. Receptor provide molecular communication between agonist and transduction process. Receptors are formed and removed continuously. Please do not reproduce, redistribute or share without the prior express permission of the author. Drug + Receptor Drug-Receptor complex Effect (Response) Receptor have active site the match the shape of the drug, (like a key and the lock). Cells may have tens or thousands of receptors for certain drugs. Cells may have different types of receptors (each specific for a particular type of drug). Please do not reproduce, redistribute or share without the prior express permission of the author. Drug-receptor binding is reversible and the response to the drug is gradually reduced once the drug leaves the receptor site. Please do not reproduce, redistribute or share without the prior express permission of the author. Receptor-Mediated Drug Effects The number of available receptor sites influence the effects of a drug. If only a few receptor sites are occupied, the response will be small. If drug dose is increased, more receptor sites are used and the response increases. However, not all receptors on a cell need to be occupied for a drug to be effective. Some extremely potent drugs are effective even when the drug occupies few receptor sites. Please do not reproduce, redistribute or share without the prior express permission of the author. 1.5 Mathematics of Drug Dosage Please do not reproduce, redistribute or share without the prior express permission of the author. OBJECTIVES At the end of the lesson, students should be able to: 1. Define Pharmacologic Math. 2. Identify healthcare provider who should learn about Pharmacologic Math. 3. Identify different measurement systems. 4. Understand conversion within system. 5. Identify type of abbreviations used in pharmacologic math. 6. Able to do simple dosage calculation for tablet and liquid. Please do not reproduce, redistribute or share without the prior express permission of the author. Pharmacologic Math To prepare and dispense medications, healthcare providers must be capable of performing a variety of pharmaceutical calculations. Please do not reproduce, redistribute or share without the prior express permission of the author. Why Nurses should study Pharmacologic Math? To perform dosage calculations To know systems of measurement and how to do convertion. Should know Basic Math skills (+, -, x, ÷) To interpret abbreviations used to describe certain units. Please do not reproduce, redistribute or share without the prior express permission of the author. Why Pharmacist/Pharmacy Assistant should study Pharmacology Math? Math is at the heart of pharmaceutical care. Pharmacological math is critical to the success of the Pharmacist and Pharmacy Assistant. Focuses on dosage calculations and basic math skills to business math concepts. Accuracy in calculations will prevent medication errors. Please do not reproduce, redistribute or share without the prior express permission of the author. CONVERSION FACTORS / EQUIVALENCIES Sometimes it is necessary to convert 1 unit to another before one can calculate a problem. When using the metric system, remember the rules for moving the decimal. Please do not reproduce, redistribute or share without the prior express permission of the author. 1 gram (g or gm) 1000 mg (milligrams) 1 milligram (mg) 1000 micrograms (mcg) 1 (household) cup 240 ml (milliliter) 1 teaspoon (tsp) 5 ml (milliliter) (not 4-5) 1 tablespoon ( T or tbs) 15 ml (milliliter) 3 teaspoons (tsp) 1 tablespoon ( T or tbs) 1 liter (L) 1000 ml (milliliter) Please do not reproduce, redistribute or share without the prior express permission of the author. Example 1: Convert 0.1 grams to milligrams. 1gram = 1000mg 0.1gram = A 1 gram x A = 0.1 gram x 1000mg A = 0.1gram x 1000mg 1gram A = 100mg Please do not reproduce, redistribute or share without the prior express permission of the author. Example 2: Convert 375mL to liters. 1L = 1000mL B = 375mL B x 1000mL = 1L x 375mL B = 1L x 375mL 1000mL X = 0.375L Please do not reproduce, redistribute or share without the prior express permission of the author. Abbreviations Is a shortcuts in writing directions for administration of medications and directions to perform activities. If used, standard abbreviations should be used. Incorrect interpretation of abbreviations can lead to dangerous situations. Please do not reproduce, redistribute or share without the prior express permission of the author. Type Of Abbreviation Abbreviation on ROA Abbreviation on administration time Abbreviation on Dosage Form Abbreviation on solution measurement Please do not reproduce, redistribute or share without the prior express permission of the author. Abbreviation on ROA I.D. Intradermal route I.M. or IM Intramuscular route I.V. or IV Intravenous route P.R. or PR By rectum SQ, sub q, subcut Subcutaneous route SL or s.l. Sublingual route V or P.V. Vaginal route Please do not reproduce, redistribute or share without the prior express permission of the author. Abbreviation on administration time Please do not reproduce, redistribute or share without the prior express permission of the author. Abbreviation on Dosage Form Please do not reproduce, redistribute or share without the prior express permission of the author. Abbreviation on solution measurement Please do not reproduce, redistribute or share without the prior express permission of the author. Oral Dosages of Drugs Solid Drug To find the correct dosage of solid oral preparation, the following formula is used: Required Dose Stock Dose = Number of tablets to be given Please do not reproduce, redistribute or share without the prior express permission of the author. Example 1: A client is ordered 150mg of aspirin. 300 mg aspirin tablets are available. How many tablets would you give? 150mg 300mg = ½ tablets Please do not reproduce, redistribute or share without the prior express permission of the author. Example 2: A physician ordered ascorbic acid 100mg and the drug is available as ascorbic acid 50mg. How many tablets would you give? 100mg 50mg = 2 tablets Please do not reproduce, redistribute or share without the prior express permission of the author. If the physician had ordered ascorbic acid 0.5g and the drug container was labeled ascorbic acid 250mg, a conversion need to be done. 1 gram = 1000mg 0.5 gram = C C x 1 gram = 0.5gram x 1000mg C = 0.5 gram x 1000mg 1 gram C = 500mg (Required dose in mg) 500mg 250mg = 2 tablets Please do not reproduce, redistribute or share without the prior express permission of the author. How many tablets containing 62.5mcg will be required to give a dose of 0.125mg? 1 mg = 1000mcg 0.125mg = D D x 1mg = 0.125mg x 1000mcg D = 0.125mg x 1000mcg 1mg D = 125mcg (Required dose in mcg) 125mcg 62.5mcg = 2 tablets Please do not reproduce, redistribute or share without the prior express permission of the author. How Many Tablets Should Be Dispensed? A prescription calls for Penicillin capsule, each containing 150mg. The signa reads : “ Penicillin cap 300mg q.i.d for 10 days” 4 times a day Please do not reproduce, redistribute or share without the prior express permission of the author. Step 1 : Calculate number of tablet to be given No of capsule to be given once 300mg 150mg = 2 capsules It means: Take Two (2) Capsules Four (4) Times a Day for Ten (10) Days Please do not reproduce, redistribute or share without the prior express permission of the author. Step 2 : Calculate the total for drugs for patient to bring home. 2 capsules x 4 times a day x 10 days = 80 tablets So, 80 capsules of Penicillin capsules (150mg) should be dispensed. Please do not reproduce, redistribute or share without the prior express permission of the author. Liquid Drug In liquid drugs, there is a specific amount of drug in a given volume of solution. For example, if a container is labeled as 10mg per 5mL (or 10mg/5mL), this means that for every 5mL of solution there is 10mg of drug. This formula used to calculate the amount of medication in solution is Required Dose Stock Dose x Stock Volume = Volume to be given Please do not reproduce, redistribute or share without the prior express permission of the author. Example 1 The physician orders oxacillin sodium 125mg PO oral suspension. The drug is labeled as 250mg/5mL. (The 5mL is the amount that contains 250mg of the drug). Required Dose Stock Dose 125mg 250mg x Stock Volume x 5mL = = Volume to be given 2.5mL Therefore, 2.5mL contains the desired dose of 125mg of oxacillin oral suspension Please do not reproduce, redistribute or share without the prior express permission of the author. Example 2 A client ordered 15mg of Stemetil. You have 2ml of solution on hand which contains 25mg Stemetil. What volume of solution would you give? Required Dose Stock Dose 15mg 25mg x Stock Volume x 2mL = = Volume to be given 1.2mL Therefore, 1.2mL contains the desired dose of 15mg of Stemetil Please do not reproduce, redistribute or share without the prior express permission of the author. Example 3 A dose of 75mg of Pethidine has been ordered. It is available in ampoules containing 100mg in 2mL. What volume must be administered? Required Dose Stock Dose 75mg 100mg x Stock Volume x 2mL = = Volume to be given 1.5mL Therefore, 1.5mL contains the desired dose of 15mg of Pethidine Please do not reproduce, redistribute or share without the prior express permission of the author. How Much Liquid Should Be Dispensed? Rx: Piriton® syrup 2mg/5ml Disp 3-days supply Sig: 4mg b.i.d Twice/ two times a day Please do not reproduce, redistribute or share without the prior express permission of the author. Step 1 : Calculate number of tablet to be given Required Dose Stock Dose 4mg 2mg x Stock Volume x 5mL = = Volume to be given 10mL The meaning is: Take Ten mililiter (10mL) Two (2) times a day for Three (3) days How much Piriton® syrup should be dispensed? Please do not reproduce, redistribute or share without the prior express permission of the author. Step 2 : Calculate the total for drugs for patient to bring home. 10mL x 2 times a day x 3 days = 60mL 60mL of Piriton® syrup should be dispensed Please do not reproduce, redistribute or share without the prior express permission of the author. Reference Holland, LM and Adams MP. 2007. Core Concepts in Pharmacology. 2nd edition.Pearson. Hitner H and Nagle B. 2002. Basic Pharmacology. 4th edition. McGraw-Hill. Please do not reproduce, redistribute or share without the prior express permission of the author. Q&A Session Please do not reproduce, redistribute or share without the prior express permission of the author. Next Topic Anti infective & Chemotherapeutic drugs Please do not reproduce, redistribute or share without the prior express permission of the author. Thank you Address Lot 33-40, Blok C, Plaza Juta, KM 7.2 Off Jalan Tuaran, 88400 Likas, Kota Kinabalu, Sabah, Malaysia Telephone +6088 431 025/35 Website kk.cyberjaya.edu.my Email [email protected]