Drug Nomenclature PDF

Welcome To Basic principles of pharmacology YFRM202 1  Welcome to this topic Pharmacology Drug nomenclature and classification YFRM202 2  Lecture Overview In this lecture you can expect to learn abo...

Welcome To Basic principles of pharmacology YFRM202 1  Welcome to this topic Pharmacology Drug nomenclature and classification YFRM202 2  Lecture Overview In this lecture you can expect to learn about the naming and classification of drugs. You have previously learned about drug sources and types. In this lecture you will build upon that knowledge and further explore the different drug names and how drugs are grouped. Throughout this lecture it will become clear that drugs may be named and grouped based on either their chemistry or therapeutic effects. 3  Learning Outcomes At the end of this lecture, you should be able to:  Explain drug nomenclature  Explain generic substitution and bioequivalence  Describe anatomical and therapeutic chemical classification of medicines (ATC) 4 Drug nomenclature YFRM300 5  Drug nomenclature Chemical name Acetylsalicylic acid International non-proprietary name (INN) - Generic name Aspirin Proprietary name - trade name /brand name disprin chemical name Describes the substance chemically. Is assigned according to chemical nomenclature rules. Is often very complex and cumbersome. Is usually not used for prescribing due to its complexity Generic name Each INN is a unique name that is globally recognized and is public property Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 8. 6  Chemical name Standard chemical nomenclature specifying the chemical structure of the drug E.g. Aspirin’s chemical name is acetylsalicylic acid INN Chemical name Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 8. 7 What is aspirin’s proprietary name? 8 Generics - brand names that produces the same drugs but came after the first company The name that pharmaceutical companies use What is aspirin’s proprietary name? 9  History of naming drugs The INN Programme (established in 1950 by the WHO) was to provide a unique single name for a pharmaceutical substance that is accepted globally. The science behind drug nomenclature has advanced over the years with the advent of better analytical techniques for identification and purity verification. Early years of the INN Programme, modification of the chemical name was an acceptable approach Later - mode of action Aim of the INN Programme (established in 1950 by the WHO) was to provide a unique single name for a pharmaceutical substance that is accepted globally. The naming of medicines is an evidence-based process and indeed it is part and parcel of evidence-based medicine. The science behind drug nomenclature has advanced over the years with the advent of better analytical techniques for identification and purity verification. With the introduction of biotechnological methods that are used in the manufacture of biologics and other biomedical treatments, the characterization of biologicals has become more precise and unambiguous. In the early years of the INN Programme, modification of the chemical name was an acceptable approach to create the INN. As more pharmaceutical substances were being discovered and many of them shared similar chemical structures, although the mode of actions could be different, this approach eventually was superseded by other methods. Moreover, structural information was less informative or useful for the prescribers and dispensers. Gradually, with the discovery of more targets and with new medicines continuously being designed and used clinically, a move to using the mode of action to name the newer pharmaceutical substances became more prevalent. This mode of action became linked to a specific ‘stem’ World Health Organization. 2018. Learning pharmacology with the use of INNs and their stems (WHO/EMP/RHT/TSN/2018.2). Available at: 10 https://cdn.who.int/media/docs/default-source/international-nonproprietary-names- (inn)/learning-pharmacology-2018.pdf?sfvrsn=d009d933_6&download=true (Date accessed: 6 May 2024). 10  Assigning INN An INN typically begins with a random prefix, possibly followed by one or more infixes/substems and terminates with a suffix/stem. A stem is a syllable (or 2-3 syllables) to indicate the pharmacological relationship and is developed based on three criteria, mode of action, and/or clinical use, and structure An INN typically begins with a random prefix, possibly followed by one or more infixes/substems and terminates with a suffix/stem. INN can also consist of more than one word. The stem, that usually coincides with the suffix, could also in principle be a different part of the word. A stem is a syllable (or 2-3 syllables) to indicate the pharmacological relationship and is developed based on three criteria, the mode of action, and/or the clinical use, and the structure. 11  INN example ‘Statins’ Atorvastatin Mode/mechanism of action: lipid lowering Fluvastatin Drug class: HMG CoA reducatase Pravastatin inhibitors Simvastatin Rosuvastatin different molecules but what is common is that they lower lipids and has HMG CoA reductase The degree of effect may vary An INN typically begins with a random prefix, possibly followed by one or more infixes/substems and terminates with a suffix/stem. INN can also consist of more than one word. The stem, that usually coincides with the suffix, could also in principle be a different part of the word. A stem is a syllable (or 2-3 syllables) to indicate the pharmacological relationship and is developed based on three criteria, the mode of action, and/or the clinical use, and the structure. 12  International nonproprietary name (INN) Active pharmaceutical ingredient (API) Internationally recognised name for a drug Generic name (do not confuse with “originator versus generic”, where both names are brand names) Most commonly used name by health care professionals Correct name to use on a prescription Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 8. 13  Proprietary name Marketed name example disprin Trade Name Brand name given to a specific drug by the manufacturer One drug (generic name) can have many trade names if there are numerous manufacturers that make and market the same drug Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 8. 14  Example Example: Paracetamol (US: acetaminophen) Chemical name: N-(4-hydroxyphenyl)acetamide INN / Generic name: Paracetamol Trade names: Panado®, Dolorol®, Perfalgan®, Painamol®, Napamol®, Gulf paracetamol® Good prescribing practice: when writing a prescription for a particular drug, use the generic name wherever possible Many different trade names, which are not all necessarily stocked or determined by tender in the state. Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 8. 15  Caution Some drug names are different in the USA Textbooks are often from the USA Examples: Paracetamol = Acetaminophen in USA (most common trade name: Tylenol®) Pethidine = Meperidine in USA Adrenaline = Epinephrine Salbutamol = Albuterol in USA Lignocaine = Lidocaine Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 8. 16  Generic substitution Substituting one brand for another YFRM300 Picture available at: https://qph.cf2.quoracdn.net/main-qimg- 3872502e6652d37e1a47ce6043c178b9 (Date accessed: 2 Jul 24) 17  Generic substitution Originator A drug product which was developed by a pharmaceutical company for the first time Frequently apply for a patent so that other companies cannot produce the same drug product for a certain number of years E.g. Viagra® - developed by Pfizer Generic When other pharmaceutical companies develop their own drug product containing the same active pharmaceutical ingredient (API) as the originator E.g. Dynafil® and Zeldina® are generics of Viagra® Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 9. 18  Generic versus originator Same API/drug (e.g. Enalapril) Same safety, quality and efficacy GENERIC VS Same API strength Determined using absorption and ORIGINATOR (e.g. 10mg) bioavailability data Same dosage form (e.g. tablets) and route of administration Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 9. https://www.sahpra.org.za/wp-content/uploads/2020/02/2.02_Quality-and- Bioequivalence-Guideline_Jul19_v7-1.pdf 19  Why generics? Cheaper than the Tested to have the same originator safety and efficacy Didn’t invest large sums of money to develop the drug or Stringent tests to prove bioequivalence are required conduct clinical trials like for registration with the originator Cost can influence patient compliance to therapy Same therapeutic effect Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 9. https://www.sahpra.org.za/wp-content/uploads/2020/02/2.02_Quality-and- Bioequivalence-Guideline_Jul19_v7-1.pdf 20  Generic substitution Section 22F of the Medicines and Related Substances Control Act 101 of 1965 states: Pharmacists must inform patients where generic medicines are available Medicines should be substituted with a generic, except when: Indicated on the prescription by the prescriber (“no substitution”/ ”no generic substitution”) Expressly forbidden by the patient The generic is more expensive than the originator API has a narrow therapeutic index Active pharmauecitical ingredient Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 8 https://www.hpcsa.co.za/Uploads/Legal/legislation/medicines_and_related_sub_act_10 1_of_1965.pdf https://www.ajol.info/index.php/samj/article/download/135557/125064 “Mandatory substitution successful” 21  Generic substitution Certain drugs which have a narrow therapeutic index where small differences in absorption and bioavailability can significantly influence plasma levels and thus activity of drugs, can be specified by trade name and should not be routinely substituted for a different generic E.g. Sodium valproate, phenytoin, warfarin, digoxin Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 8 https://www.hpcsa.co.za/Uploads/Legal/legislation/medicines_and_related_sub_act_10 1_of_1965.pdf https://www.ajol.info/index.php/samj/article/download/135557/125064 “Mandatory substitution successful” 22  Bioequivalence 2 drug products are considered to be bioequivalent if they exhibit similar bioavailability Their rate and extent of absorption is similar Determined by Cmax and AUC Drug products may be considered bioequivalent in extent and rate of absorption if their plasma concentration curves are essentially superimposable In order to determine that two medicines are bioequivalent there must be no more than a 20% difference between the AUC and Cmax. Needs to be tested when a drug manufacturer wants to apply to register a new generic with South African Health Products Regulatory Authority (SAHPRA) Brenner and Stevens’ pharmacology. 2023. Chapter 1. Page 8 https://www.sahpra.org.za/wp-content/uploads/2020/02/2.02_Quality-and- Bioequivalence-Guideline_Jul19_v7-1.pdf 23  Bioequivalence https://bpac.org.nz/bpj/2009/generics/img/bio_graph.jpg Comparison of Cmax, Tmax and AUC between 2 drugs. This is used to determine whether the one drug can be considered bioequivalent to the other and can be registered and marketed as a generic formulation. 24 Drug classification / groups YFRM300 25  Anatomical therapeutic chemical (ATC) classification Drugs are classified in groups at five different levels: 1. ATC 1st level: The system e.g statins act on blood 2. ATC 2nd level: Therapeutic / pharmacological subgroup what it is used for?e.g pain 3. ATC 3rd level: Pharmacological subgroup classes- painkiller, antibiotic 4. ATC 4th levels: Chemical subgroup chemical derivative 5. ATC 5th level: Chemical substance (drug, INN/ API) https://www.who.int/tools/atc-ddd-toolkit/atc-classification ATC 1st level The system has fourteen main anatomical or pharmacological groups (1st level). The ATC 1st levels are shown in the figure. ATC 2nd level Pharmacological or Therapeutic subgroup ATC 3rd& 4th levels Chemical, Pharmacological or Therapeutic subgroup ATC 5th level Chemical substance (INN) 26  Anatomical or pharmacological groups GIT e.g diabetes lipids lowering, blood clotting helps heart (1st level) https://www.who.int/tools/atc-ddd-toolkit/atc-classification 27  Anatomical therapeutic chemical (ATC) classification The complete classification of simvastatin illustrates the structure of the code: Code Example of paracetamol Description C Cardiovascular system Anatomical system C10 Lipid modifying agents Therapeutic effect C10A Lipid modifying agents, plain Pharmacological subgroup C10AA HMG CoA reductase inhibitors Pharmacological / Chemical subgroup C10AA01 Simvastatin INN / API (drug name) under cardiovascular system https://www.who.int/tools/atc-ddd-toolkit/atc-classification 28  Anatomical therapeutic chemical (ATC) classification The complete classification of paracetamol illustrates the structure of the code: Code Example of paracetamol Description N Central nervous system Anatomical system N02 Analgesics Therapeutic effect (mechanism of action) N02B Other analgesics and antipyretics Pharmacological subgroup / drug class N02BE Anilides Chemical subgroup N02BE01 Paracetamol INN / API (drug name) https://www.who.int/tools/atc-ddd-toolkit/atc-classification 29  Checklist Can you...  Explain drug nomenclature?  Explain generic substitution and bioequivalence?  Describe anatomical and therapeutic chemical classification of medicines (ATC)? Did you...  Complete The Attendance Register? 30  References Brenner & Stevens’ Pharmacology, 6th Edition: 2023. Chapter 1 introduction to pharmacology and drug names. Page 3 – 9. Rang and Dale’s pharmacology, 10th Edition. 2023. Chapter 1 What is pharmacology. Page 1-5. World Health Organization. 2018. Learning pharmacology with the use of INNs and their stems (WHO/EMP/RHT/TSN/2018.2). Available at: https://cdn.who.int/media/docs/default-source/international- nonproprietary-names-(inn)/learning-pharmacology-2018.pdf?sfvrsn=d009d933_6&download=true (Date accessed: 6 May 2024). 31  Feedback Please be kind enough to take a minute and rate this lesson and provide a little feedback to help us gain a better understanding of your learning experience. Let us know what you really enjoyed and what we can do better for you. Click on the link at the bottom of the lesson page on I-learn to provide feedback for this lesson. +- (2mins) 32 33 34