Rapid Clinical Pharmacology

A Student Formulary

Andrew Batchelder, Charlene Rodrigues, Ziad Alrifai

• Publisher: Wiley-Blackwell
• Year: 2011
• Print ISBN:
  9780470654415
• eBook ISBN:
  9781118293065
• Edition: 1
• Topic: Medicine
• Subtopic: Pharmacology

This pocket reference guide is a must for all medical students and junior doctors preparing for exams in pharmacology or needing a rapid reminder during a clinical attachment.

In light of the growing pressures on those who prescribe drugs to patients, increasing emphasis has been placed on the importance of pharmacology in the undergraduate medical curriculum. Rapid Clinical Pharmacology, with its concise, easy-to-use approach, offers an appealing format for students to use in both clinical practice and exam preparation and its 'one-page per drug/class' layout easily facilitates the generation of a personal student formulary.

Each chapter of the book mirrors each section of the BNF to allow easy cross-referencing and then each chapter is divided into consistent sections as per other books in the Rapid series.

Rapid Clinical Pharmacology will also be available as a mobile application for iPhone, iPod Touch, iPad and Blackberry. See wiley.com/go/mededapps for further details.

CARDIOVASCULAR SYSTEM

α-adrenoceptor antagonists (α blockers)

EXAMPLES Doxazosin, prazosin, tamsulosin, alfuzosin

MECHANISM OF ACTION Inhibit α₁-adrenoceptors in arterioles, thereby reducing tone of vascular smooth muscle and reducing total peripheral resistance. Inhibition of α₁-adrenoceptors in periurethral prostatic stroma results in relaxation of internal urethral sphincter and some relief of obstructive urinary symptoms in males.

INDICATIONS

• Hypertension (i.e. doxazosin, particularly in resistant cases as part of polytherapy)
• Benign prostatic hyperplasia

CAUTIONS AND CONTRA-INDICATIONS

• Caution in patients with a susceptibility to heart failure

SIDE-EFFECTS

• Postural hypotension
• Dizziness
• Weakness and fatigue
• Reflex tachycardia
• Headache
• Dry mouth
• Ejaculatory failure

METABOLISM AND HALF-LIFE Variable – e.g. doxazosin (t_½ ~22 h) extensively metabolised by liver; alfuzosin (t_½ ~3–5 h) partially metabolised.

MONITORING May cause severe first-dose hypotension therefore need to start at low dose and warn patient of side-effects.

DRUG INTERACTIONS

• Enhanced hypotensive effect with antihypertensives and alcohol

IMPORTANT POINTS

• Centrally acting α₂-adrenoceptor agonists (e.g. clonidine, α methyldopa) also have an antihypertensive effect (mediated via suppression of the vasomotor centre in the brain). These agents are rarely used due to infrequent but potentially severe adverse effects (α methyldopa may cause hepatitis). α methyldopa continues to be used for hypertension in pregnancy

Adenosine

MECHANISM OF ACTION Stimulates specific A1 receptors on the surface of cardiac cells thus influencing adenosine-sensitive K⁺ channel and cAMP production. This leads to prolonged conduction through the AV node, often with a high degree AV block.

INDICATIONS

• Rapid reversal of SVT to sinus rhythm
• SVT with aberrant conduction (specialist use only)
• Aiding diagnosis of narrow or broad complex tachycardias

CAUTIONS AND CONTRA-INDICATIONS

• Second and third degree AV block
• Sick sinus syndrome
• Prolonged QT syndrome
• Severe hypotension
• Decompensated heart failure
• Asthma

SIDE-EFFECTS

• Chest pain
• Dyspnoea
• Bronchospasm
• Nausea
• Severe bradycardia
• Choking sensation
• Light-headedness

METABOLISM AND HALF-LIFE t_½ <2s. Metabolised by uptake into red blood cells and deaminated in plasma.

MONITORING Cardiac monitoring required.

DRUG INTERACTIONS

• Effects of adenosine are potentiated by dipyridamole

IMPORTANT POINTS

• Ensure patient is linked to a cardiac monitor or defibrillator
• Attempt vasovagal manoeuvres prior to administration unless contra-indicated
• If no response to the above, start with 6mg IV rapid bolus given through a large vein and flush with 20 ml of normal saline
• Repeat with 12mg after 1–2 minutes if no response. A further 12mg can be given
• Early specialist cardiology advice is warranted if no response to 12mg of adenosine or if adverse signs are present at any stage e.g. heart failure
• Patients should be informed prior to adenosine administration of possible chest pain and the sensation of the heart ceasing to beat

Aldosterone antagonists

EXAMPLES Spironolactone, eplerenone

MECHANISM OF ACTION Competitive antagonist at intracellular aldosterone receptors in renal tubules causing reduced production of aldosterone-induced proteins. This indirectly reduces activity of Na⁺/K⁺ ATPase in the collecting ducts, increasing excretion of Na⁺ and decreasing K⁺ loss. Spironolactone, in particular, also acts on receptors in other tissues, including androgen receptors.

INDICATIONS

• Congestive cardiac fai...

Table of contents

• Cover
• Title Page
• Copyright
• Preface
• List of abbreviations
• BASIC PHARMACOKINETIC CONCEPTS
• GASTROINTESTINAL SYSTEM
• CARDIOVASCULAR SYSTEM
• RESPIRATORY SYSTEM
• CENTRAL NERVOUS SYSTEM
• INFECTIONS
• ENDOCRINE SYSTEM
• OBSTETRICS, GYNAECOLOGY AND URINARY
• MALIGNANT DISEASE AND IMMUNOSUPPRESSION
• MUSCULOSKELETAL AND JOINT DISEASES
• EYE
• ANAESTHESIA
• INTRAVENOUS FLUIDS
• BLOOD AND TRANSFUSION MEDICINE
• Index of drugs
• Wiley End User License Agreement