drugs available has expanded hugely since the first edition of this book was published almost 40 years ago, in preparing this text we continue to be guided by the principles established in that edition: we have retained a clear focus on practical elements and clinical relevance throughout, in order to maximise utility for the student or practising clinician. Rather than indulgence in exhaustive detail, we have chosen to set out concisely and with clarity the principles which guide clinicians in their choices and have made use of illustrative examples from scenarios commonly encountered on wards and in clinics. In doing so, we hope to provide the reader with an accessible and helpful guide which imparts a useful understanding of not only how, but also when to use drugs.
Gerard A. McKay
Neil D. Ritchie
Matthew R. Walters
Glasgow
October 2020
Contributors
The following have contributed substantially to the writing, revision and rewriting of the chapters for this tenth edition.
Andrea Llano NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 1, Pharmacodynamics and pharmacokinetics
Gerard A. McKay NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 1, Pharmacodynamics and pharmacokinetics Chapter 2, Clinical trials and drug development Chapter 10, Drugs and endocrine disease
Alan Cameron College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK Chapter 2, Clinical trials and drug development
Matthew R. Walters College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK Chapter 2, Clinical trials and drug development
Ailsa Brown Scottish Medicines Consortium, Glasgow, UK Chapter 3, Pharmacoeconomics: the economic evaluation of new drugs
Kenneth Paterson NHS Greater Glasgow and Clyde, Glasgow, UK (formerly) Chapter 3, Pharmacoeconomics: the economic evaluation of new drugs
Neil D. Ritchie NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 4, Practical prescribing Chapter 9, Infection
Rosemary Haddock NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 5, Gastrointestinal system
Adrian Stanley NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 5, Gastrointestinal system
Kieran Docherty College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK Chapter 6, Cardiovascular system
Ninian Lang NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 6, Cardiovascular system
Malcolm Shepherd NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 7, Respiratory system
Azmil Abdul‐Rahman College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK Chapter 8, Nervous system
Jamie Herron College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK Chapter 8, Nervous system
Sam Leighton College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK Chapter 8, Nervous system
Jonathan Cavanagh College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK Chapter 8, Nervous system
Celia Jackson NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 9, Infection
Heather Black NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 9, Infection
Emma Johns NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 10, Drugs and endocrine disease
Ceilidh Grimshaw NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 11, Genitourinary system
Caroline Bruce College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, UK Chapter 12, Malignant disease
Charlie Gourley College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, UK Chapter 12, Malignant disease
Mark Rafferty NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 13, Drugs and the blood
Hanna Johnsson College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK Chapter 14, Musculoskeletal system Chapter 15, Immunopharmacology
Iain McInnes College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK Chapter 14, Musculoskeletal system Chapter 15, Immunopharmacology
Sharon Irvine Royal Liverpool and Broadgreen University Hospital NHS Trust, Liverpool, UK Chapter 16, Travel medicine
Malcolm Sim NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 17, Analgesia and anaesthesia
Mohammed Al‐Haddad NHS Greater Glasgow and Clyde, Glasgow, UK Chapter 17, Analgesia and anaesthesia
James Dear NHS Lothian, Edinburgh, UK Chapter 18, Poisoning and drug overdose
1 Pharmacodynamics and pharmacokinetics
A 50‐year‐old obese man with type 2 diabetes, hypertension and hyperlipidaemia has made arrangements to see his general practitioner to review his medications. He is on three different drugs for his diabetes, four different anti‐hypertensives, a statin for his cholesterol and a dispersible aspirin. These medications have been added over a period of 2 years despite him not having any symptoms and he feels that if anything they are giving him symptoms of fatigue and muscle ache. He has also read recently that aspirin may actually be bad for patients with diabetes. He is keen to know why he is on so many medications, if the way he is feeling is due to the medications and whether they are interfering with the action of each other. What knowledge might help the general practitioner deal with this?
Introduction
A basic knowledge of the mechanism of action of drugs and how the body deals with drugs allows the clinician to prescribe safely and effectively. Prior to the twentieth century, prescribing medication was based on intelligent observation and folklore with medical practices depending largely on the administration of mixtures of natural plant or animal substances. These preparations contained a number of pharmacologically active agents in variable amounts (e.g. powdered bark from
