Book contents
- Frontmatter
- Contents
- Introduction
- How to use this book
- Abbreviations
- Acknowledgements
- DRUGS: AN A–Z GUIDE
- SHORT NOTES
- Routes of administration
- Loading dose
- Drug metabolism
- Enzyme systems
- Drug excretion
- Drug tolerance
- Drug interactions
- Therapeutic drug monitoring
- Target range of concentration
- Pharmacology in the critically ill
- Cardiopulmonary resuscitation
- Drugs in advanced life support
- Management of acute major anaphylaxis
- Management of severe hyperkalaemia
- Management of malignant hyperthermia
- Sedation, analgesia and neuromuscular blockade
- A practical approach to sedation and analgesia
- Opioid Conversion table
- Management of status epilepticus
- Prevention of delirium tremens and alcohol withdrawal syndrome
- Prevention of Wernicke–Korsakoffsyndrome
- Anti-arrhythmic drugs
- Inotropes and vasopressors
- Bronchospasm
- Anti-ulcer drugs
- Immunonutrition in the ICU
- Corticosteroids
- Short synacthen test
- Bone marrow rescue following nitrous oxide
- Antioxidants
- Post-splenectomy prophylaxis
- Anti-microbial drugs
- Bacterial gram staining
- Antibiotics: sensitivities
- Renal replacement therapy
- Extracorporeal drug clearance: basic principles
- Drug doses in renal failure/renal replacement therapy
- Chemical pleurodesis of malignant pleural effusion
- APPENDICES
- DRUG INDEX
- IV COMPATIBILITY CHART
Loading dose
Published online by Cambridge University Press: 05 November 2014
- Frontmatter
- Contents
- Introduction
- How to use this book
- Abbreviations
- Acknowledgements
- DRUGS: AN A–Z GUIDE
- SHORT NOTES
- Routes of administration
- Loading dose
- Drug metabolism
- Enzyme systems
- Drug excretion
- Drug tolerance
- Drug interactions
- Therapeutic drug monitoring
- Target range of concentration
- Pharmacology in the critically ill
- Cardiopulmonary resuscitation
- Drugs in advanced life support
- Management of acute major anaphylaxis
- Management of severe hyperkalaemia
- Management of malignant hyperthermia
- Sedation, analgesia and neuromuscular blockade
- A practical approach to sedation and analgesia
- Opioid Conversion table
- Management of status epilepticus
- Prevention of delirium tremens and alcohol withdrawal syndrome
- Prevention of Wernicke–Korsakoffsyndrome
- Anti-arrhythmic drugs
- Inotropes and vasopressors
- Bronchospasm
- Anti-ulcer drugs
- Immunonutrition in the ICU
- Corticosteroids
- Short synacthen test
- Bone marrow rescue following nitrous oxide
- Antioxidants
- Post-splenectomy prophylaxis
- Anti-microbial drugs
- Bacterial gram staining
- Antibiotics: sensitivities
- Renal replacement therapy
- Extracorporeal drug clearance: basic principles
- Drug doses in renal failure/renal replacement therapy
- Chemical pleurodesis of malignant pleural effusion
- APPENDICES
- DRUG INDEX
- IV COMPATIBILITY CHART
Summary
An initial loading dose is given quickly to increase the plasma concentration of a drug to the desired steady-state concentration. This is particularly important for drugs with long half-lives (amiodarone, digoxin). It normally takes five half-lives to reach steady-state if the usual doses are given at the recommended interval. Thus, steady-state may not be reached for many days. There are two points worth noting:
• For IV bolus administration, the plasma concentration of a drug after a loading dose can be considerably higher than that desired, resulting in toxicity, albeit transiently. This is important for drugs with a low therapeutic index (digoxin, theophylline). To prevent excessive drug concentrations, slow IV administration of these drugs is recommended.
• For drugs that are excreted by the kidneys unchanged (gentamicin, digoxin) reduction of the maintenance dose is needed to prevent accumulation. No reduction in the loading dose is needed.
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- Chapter
- Information
- Handbook of Drugs in Intensive CareAn A-Z Guide, pp. 247Publisher: Cambridge University PressPrint publication year: 2014