Section 5.2: MICA Pharmacology Flashcards
Adenosine – Presentation/s
- 6mg in 2mL glass ampoule
Adenosine – Pharmacology
A naturally occurring purine nucleoside found in all body cells
Actions:
- Slows conduction through the A-V node, resulting in termination of re-entry circuit activity within or including the A-V nodal pathway
Adenosine – Metabolism
- By adenosine deaminase in red blood cells and vascular endothelium
Adenosine – Primary emergency indication/s
- AVNRT with adequate or inadequate perfusion but not deteriorating rapidly
- AVRT and associated Wolff-Parkinson-White (WPW) or other accessory tract SVT with adequate or inadequate perfusion but not deteriorating rapidly
Adenosine – Contraindication/s
- Second or third degree A-V block (may produce prolonged sinus arrest / A-V blockade)
- Atrial fibrillation
- Atrial flutter
- Ventricular tachy-arrhythmias
- Known hypersensitivity
Adenosine – Precaution/s
- Adenosine may provoke bronchospasm in the asthmatic Pt
- Adenosine is antagonized by methylxanthines (e.g. caffeine or theophyllines). The drug may not be effective in Pts with large caffeine intake or those on high doses of theophylline medication
Adenosine – Route/s of administration
- IV
Adenosine – Side effects
Usually brief and transitory:
- Transient arrhythmia (including asystole, bradycardia or ventricular ectopy) may be experienced following reversion
- Chest pain
- Dyspnoea
- Headache or dizziness
- Nausea
- Skin flushing
Adenosine – Special notes
- Adenosine has a very short half life. It should be administered through an IV as close to the heart as practicable, such as the cubital fossa
Adenosine – Onset, Peak & Duration times
IV effects:
- Onset: N/A
- Peak: N/A
- Duration: < 10 sec
Amiodarone – Presentation/s
- 150mg in 3mL glass ampoule
Amiodarone – Pharmacology
- Class III anti-arrhythmic agent
Amiodarone – Metabolism
- By the liver
Amiodarone – Primary emergency indication/s
- VF / pulseless VT refractory to cardioversion
- Sustained or recurrent VT
Amiodarone – Contraindication/s
- VF / pulseless VT refractory to cardioversion:
* Nil of significance in this indication
2. VT (conscious):
- Inadequate perfusion
- Pregnancy
3. Tri-cyclic Antidepressant (TCA) Overdose
Amiodarone – Precaution/s
- Following Fentanyl administration
Amiodarone – Route/s of administration
- IV
Amiodarone – Side effects
- Hypotension
- Bradycardia
Amiodarone – Special notes
- Amiodarone is incompatible with saline. Glucose 5% must be used as dilutant when preparing an IV infusion.
- An IV infusion of Amiodarone may be required during inter-hospital transfer. This will be prescribed by the referring physician and will normally be at a dose of 10 – 20mg / kg run over 24hrs.
Amiodarone – Onset, Peak & Duration times
IV effects (bolus):
- Onset: 2min
- Peak: 20min
- Duration: 2hr
Atropine – Presentation/s
- 0.6mg in 1mL polyamp
- 1.2mg in 1mL polyamp
Atropine – Pharmacology
An anti-cholinergic agent
Actions:
- Inhibits the actions of acetylcholine on post-ganglionic cholinergic nerves at the neuro-effector site, e.g. as a vagal blocker, and allows sympathetic effect to:
- Increase HR by increasing SA node firing rate
- Increase the conduction velocity through the A-V node
- Antidote to reverse the effects of cholinesterase inhibitors (e.g. organophosphate insecticides) at the post-ganglionic neuro-effector sites of cholinergic nerves to:
- Reduce the excessive salivary, sweat, GIT and bronchial secretions; and
- Relax smooth muscles
Atropine – Metabolism
- By the liver. Excreted mainly by the kidneys.
Atropine – Primary emergency indication/s
- Bradycardia with poor perfusion
- Organophosphate poisoning with excessive cholinergic effects
Atropine – Contraindication/s
- Officially, nil of significance in the above indications
- ? Known hypersensitivity to Atropine or its derivatives.
Atropine – Precaution/s
- Atrial flutter
- Atrial fibrillation
- Do not increase HR above 100bpm except in children under 6 years
- Glaucoma
Atropine – Route/s of administration
- IV
- ETT
Atropine – Side effects
- Tachycardia
- Palpitations
- Dry mouth
- Dilated pupils
- Visual blurring
- Retention of urine
- Confusion, restlessness (in large doses)
- Hot, dry skin (in large doses)
Atropine – Special notes
N/A
Atropine – Onset, Peak & Duration times
IV effects:
- Onset: < 2min
- Peak: < 5min
- Duration: 2 – 6hr
Dexamethasone – Presentation/s
- 8mg in 2mL glass vial
Dexamethasone – Pharmacology
A corticosteroid secreted by the adrenal cortex
Actions:
- Relieves inflammatory reactions
- Provides immunosuppression
Dexamethasone – Metabolism
- By the liver and other tissues. Excreted predominantly by the kidneys
Dexamethasone – Primary emergency indication/s
- Bronchospasm associated with acute respiratory distress not responsive to nebulised Salbutamol
- Anaphylaxis
- Acute exacerbation of COPD
Dexamethasone – Contraindication/s
- Known hypersensitivity
Dexamethasone – Precaution/s
- Solutions which are not clear or are contaminated should be discarded
Dexamethasone – Route/s of administration
- IV
- IM
Dexamethasone – Side effects
- Nil of significance in the above indication
Dexamethasone – Special notes
- Does not contain an antimicrobial agent, therefore use the solution immediately and discard any residue
Dexamethasone – Onset, Peak & Duration times
IV effects:
- Onset: 30 – 60min
- Peak: 2hr
- Duration: 36 – 72hr
Dextrose 5% – Presentation/s
- 100mL infusion soft pack
Dextrose 5% – Pharmacology
An isotonic crystalloid solution
Composition:
- Sugar – 5% dextrose
- Water
Actions:
- Provides a small source of energy
- Supplies body water
Dextrose 5% – Metabolism
Dextrose:
- Broken down in most tissues
- Stored in the liver and muscle as glycogen
Water:
- Distributed throughout total body water, mainly in the extracellular fluid compartment
- Excreted by the kidneys
Dextrose 5% – Primary emergency indication/s
- Vehicle for dilution and administration of IV emergency drugs
Dextrose 5% – Contraindication/s
- Nil of significance in the above indication
Dextrose 5% – Precaution/s
- Nil of significance in the above indication
Dextrose 5% – Route/s of administration
- IV infusion
Dextrose 5% – Side effects
- Nil of significance in the above indication
Dextrose 5% – Special notes
IV half life:
- Approximately 20 – 40min
Dextrose 5% – Onset, Peak & Duration times
- Onset: N/A
- Peak: N/A
- Duration: N/A
Enoxaparin (Clexane) – Presentation/s
- 100mg in 1mL pre-filled syringe with graduated markings (SC injection)
- 40mg in 0.4mL glass ampoule (IV bolus)
Enoxaparin (Clexane) – Pharmacology
- Binds to and accelerates the action of antithrombin III which inactivates clotting factors IIa (thrombin) and Xa, inhibiting the conversion of prothrombin to thrombin
Enoxaparin (Clexane) – Metabolism
- Metabolised by the liver
Enoxaparin (Clexane) – Primary emergency indication/s
- Acute STEMI
Enoxaparin (Clexane) – Contraindication/s
- Known allergy or hypersensitivity
- Active bleeding (eg peptic ulcer, intracranial haemorrhage)
- Bleeding disorders
- Severe hepatic impairment / disease
- Heparin-induced thrombocytopenia (HIT)
Enoxaparin (Clexane) – Precaution/s
- Renal impairment
- If Pt > or = 75yo, omit the initial IV bolus dose and only administer 0.75mg / kg SC injection with a maximum 75mg SC