Chapter 10. Drug formulary
The Medicines Act allows ambulance paramedics to supply and administer prescription only medications in circumstances specified by local paramedic steering committees or their equivalent.
The Joint Royal Colleges Ambulance Liaison Committee (JRCALC) makes applications for exemption for the drugs listed in the formulary below.
The JRCALC National Clinical Guidelines for use by UK ambulance services provide the most up-to-date list of relevant drugs (see: www.asancep.org.uk/JRCALC/guidelines).
The names of a drug
Each drug has several ‘names’ as the full chemical name is usually unwieldy:
• Chemical name: 4-amino-5-chloro- N-[2-(dimethylamino)ethyl] 1-2-methoxybenzamide
• Generic name: metoclopramide
• Trade name: Maxolon.
Routes of administration
Enteral routes of administration:
• Oral
• Rectal
• Sublingual
• Buccal.
Parenteral routes of administration:
• Dermal patches
• Intradermal
• Intramuscular
• Subcutaneous
• Intravenous
• Inhaled or nebulised
• Intraosseous.
Half-life
This is the time it takes for the plasma concentration of a drug in the body to halve.
After one half-life, only 50% remains, after two half-lives, only 25% remains and so on.
This is important because drugs with a long half-life take a long time to be eliminated compared to those with a short half-life.
Naloxone, the antidote to morphine, has a much shorter half-life than morphine itself.
Prehospital formulary
Amiodarone
Main prehospital use
• Ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) refractors to three countershocks
• VT with chest pain, heart failure, or heart rate >150 bpm.
Action
An antiarrhythmic drug, which lengthens cardiac action potential and effective refractory period.
Preparations
30 mg/mL, 10 mL ampoule for intravenous injection.
Indications
Replaces lidocaine for:
• VF or pulseless VT
• VT with either chest pain, heart failure, or heart rate >150 bpm provided SBP >90 mmHg.
Cautions
None in cardiac arrest situations.
Contraindications
None in cardiac arrest situations.
For VT, hypotension (BP, 90 mmHg), bradycardia, heart block, thyroid dysfunction, iodine allergy, respiratory failure, congestive heart failure, decompensated cardiomyopathy, pregnancy, breast-feeding.
Side-effects
Not relevant in cardiac arrest situations.
Following treatment for VT: severe bradycardia, vasodilation and hypotension, bronchospasm, arrhythmias ( torsade de pointes).
Dose
• Cardiac arrest: Following persistent VF or VT administer 300 mg IV after 3rd shock. A further 150 mg may also be used
• VT: 150 mg over 10 minutes (3 minutes if life-threatening). May be repeated once after 10 minutes.
Aspirin
Aspirin (acetylsalicylic acid) decreases platelet aggregation and inhibits clot formation on the arterial side of the circulation. Its use can reduce mortality associated with myocardial infarction and unstable angina. When indicated, a 300 mg tablet should be given regardless of any previous aspirin taken that day. In children under 12 years old, aspirin is associated with Reye’s syndrome (acute encephalopathy and liver damage) and is contraindicated.
Main prehospital use
Acute coronary syndromes.
Other uses
• Prevention of thrombotic cardiovascular or cerebrovascular disease
• Simple oral analgesic and mild antiinflammatory.
Action
• Antiplatelet activity prevents or limits formation of clots
• Decreased perception of pain
• Antipyretic (lowers temperature).
Preparations
Dispersible tablet 300 mg.
Indications
Adults with ischaemic chest pain.
Cautions
• Asthma
• Pregnancy
• Kidney or liver failure
• Gastric or duodenal ulcer.
Contraindications
• Known hypersensitivity
• Children under 16 years
• Patients with known clotting disorders (e.g. haemophilia).
Side-effects
• Gastric irritation and bleeding
• Bronchospasm in some asthmatics.
Administration
Place on the tongue and chew or dissolved in water and drink.
Dose
300 mg single dose.
Atropine
Main prehospital use
Management of asystolic cardiac arrest and symptomatic bradycardia (heart rate <60). No longer recommended for routine use in asystole or PEA.
Other uses
Organophosphate poisoning.
Action
• Blocks vagal (parasympathetic) tone – blocks effect of vagus nerve at sinoatrial and atrioventricular nodes, thus increasing sinus automaticity and facilitating AV node conduction
• Reduces likelihood of VF triggered by hypoperfusion associated with extreme bradycardia.
Preparations
• 10 mL disposable syringe with 1 mg (100 μg/mL)
• 5mL disposable syringe with 1 mg (200 μg/mL)
• 10 mL disposable syringe with 3 mg (300 μg/mL)
• 1 mL ampoule with 600 μg/mL.
Indications
1. Symptomatic bradycardia associated with any of:
• Shock
• Syncope
• Myocardial Ischaemia
• Heart failure
2. Heart rate <60 and any indication of high risk of asystole:
• Recent asystole
• Mobility II AV block
• Complete heart block with wide QRS
• Ventricular pauses >3 seconds
3. Organophosphate poisoning.
Cautions
Give cautiously to avoid tachycardia post-myocardial infarction (increases myocardial oxygen demand and worsens ischaemia).
Contraindications
Bradycardia associated with hypothermia.
Side-effects
• Dilation of pupils and blurred vision
• Dry mouth
• Urine retention
• Confusion
• Tachycardia.
Administration
IV
Dose
• 0.5–3 mg IV for symptomatic bradycardia or high risk of asystole
• Children, 20 μg/kg (maximum cumulative dose 0.1 mg, minimum 100 μg)
• Organophosphate poisoning, 2 mg IV repeated as required until skin becomes flushed and dry, pupils dilate and tachycardia develops.
Benzylpenicillin
Benzylpenicillin is one of the penicillin group of drugs. It interferes with bacterial cell wall production and kills a range of bacteria which include those commonly responsible for meningococcal septicaemia and meningitis. Although the most important side-effect of benzylpenicillin is an allergic reaction, very few patients are at risk of anaphylaxis. Many patients think that they may be allergic to penicillin because of transient rashes or an episode of diarrhoea. If a patient is suspected of having meningococcal septicaemia, only a genuine (proven) history of penicillin allergy should stop benzylpenicillin being given.
Main prehospital use
The treatment of meningococcal septicaemia.
Other uses
None prehospital.
Action
Bactericidal by interfering with bacterial cell wall synthesis.
Preparations
Ampoule containing 600 mg of penicillin G (benzylpenicillin) in powder form.
Indications
• Meningococcal septicaemia
• Meningitis.
Cautions
• Previous side-effects after penicillin
• Renal impairment.
Contraindications
Genuine penicillin allergy.
Side-effects
• Rare in context of severe infection
• Hypersensitivity reactions (e.g. urticaria)
• Anaphylaxis (rare)
• Convulsions in high doses
• Hypotension (due to action of drug in releasing toxins. Manage with IV fluid challenges).
Administration
IV or IM.
Dose
Dissolve each 600 mg in 10 mL sterile water for IV use, and 2 mL sterile water for IM use. Give:
• Adult and child older than 9 years – 1200 mg (20 mL IV, 4 mL IM)
• Child 1–9 years – 600 mg (10 mL IV, 2 mL IM)
• Infant – 300 mg (5 mL IV, 1 mL IM).
Chlorpheniramine
Chlorpheniramine is used as a second-line drug in the management of anaphylactic reactions, and as the first-line treatment of less severe allergic reactions, such as severe itching.
Main prehospital use
Management of anaphylactic and allergic reactions.
Other uses
None in the prehospital setting.
Action
Chlorpheniramine blocks the action of histamine released as part of the body’s response to allergens.
Preparation
10 mg/mL, 1 mL ampoule.
Indications
• Severe anaphylactic reactions (after administration of adrenaline)
• Allergic reactions causing distress (e.g. severe itching).
Cautions
• Hypotension
• Epilepsy
• Glaucoma
• Hepatic disease.
Contraindications
• Hypersensitivity
• <1 year of age.
Side-effects
Hypotension if administered rapidly.
Administration
Slow IV injection over 1 minute.
Dosage
• Adult >12 years 10 mg
• Child 6–12 years 5 mg
• Child 1–5 years 2.5 mg.
Compound sodium lactate (hartmann’s/ ringers lactate)
Main prehospital uses
Fluid replacement therapy.
Other uses
None.
Action
As an infusion, transiently increases intravascular volume.
Preparations
• 500 and 1000 mL bags
• 5 and 10 mL ampoules.
Indications
• Status asthmaticus (to limit formation of dry mucous plugs)
• Hypovolaemic shock in the absence of a radial pulse
• Burns
• Anaphylaxis
• Hyperthermia
• Dehydration.
Cautions
None.
Contraindications
• Hyperglycaemic ketoacidosis
• Crush injury.
Side-effects
• Fluid overload in patients with uncontrolled haemorrhage can cause clot disruption and increased bleeding
• Fluid overload causing heart failure (particularly in the elderly)
• Exacerbation of pre-existing acidosis.
Administration
IV infusion or bolus.
Dose
Adults with dehydration, status asthmaticus, hyperthermia:
• Give 500 mL infusion in 20 minutes repeated to effect (maximum dose 2000 mL).
Children with dehydration, status asthmaticus, hyperthermia:
• Give 20 mL/kg bolus repeated once to effect.
Adults and children with hypovolaemic shock or burns, see Figure 10.1.
Do not give compound sodium lactate to patients with crush syndrome.
Diazepam
Diazepam is the benzodiazepine that has been most commonly used in the management of seizures and status epilepticus. It is ideally given intravenously in someone who is actively fitting at the scene or is having repeated fits. It is given IV as the emulsion Diazemuls to reduce the risk of venous thrombophlebitis. Rectal diazepam is given when IV access cannot be obtained.
Main prehospital use
Management of seizures.
Other uses
Cocaine toxicity.
Action
CNS depressant and anticonvulsant.
Preparations
• Rectal tubes containing 5 mg or 10 mg
• 2 mL ampoule (diazepam emulsion) containing 10 mg (5 mg/mL).
Indications
Prolonged or repeated seizures such as may occur in:
• Status epilepticus
• Convulsions secondary to infections
• Alcohol withdrawal seizures
• Convulsions due to poisoning
• Eclampsia
• Head injury (rule out hypoxia).
Symptomatic cocaine toxicity
• Severe hypertension
• Chest pain
• Fitting.
Cautions
• Respiratory disease/depression
• History of drug or alcohol abuse
• Reduce dose in elderly and debilitated
• Facilities for ventilatory support should be immediately available
• Consider doses previously administered by carers
• Use of CNS depressants.
Contraindications
• Known hypersensitivity
• Respiratory failure.
Side-effects
• Respiratory depression (especially with opioids and alcohol)
• Apnoea
• CNS depression and loss of consciousness
• Cardiovascular depression and postural hypotension
• Amnesia.
Administration
• IV through a large proximal vein at a rate of 3 mg/min
• Rectal via a tube which should be inserted no more than 2 cm in children and 3–4 cm in adults (tubes have markers)
• Rectal tubes should be held in place for a few moments after expelling the contents and the patient’s buttocks held together to reduce seepage from the rectum.
Entonox
Nitrous oxide is an anaesthetic gas, which is rapidly absorbed by inhalation. A mixture of nitrous oxide and oxygen containing 50% of each gas (Entonox) is used in prehospital care to gain rapid control of pain without loss of consciousness. It is administered by the casualty via a demand valve. Slow, deep breaths are required. The casualty must be conscious, cooperative and have sufficient respiratory excursion to operate the demand valve. Nitrous oxide is extremely soluble and will diffuse rapidly into any gas-filled cavity; it may thus increase the size of a pneumothorax. At temperatures below −7°C, nitrous oxide may liquefy and the oxygen and nitrous oxide will separate. The patient may then inhale pure oxygen followed by pure nitrous oxide. It is not adequate to simply shake the cylinder in these situations. Cylinders need to be kept at temperatures above freezing.
Main prehospital use
Rapid control of pain
May be used whilst preparing to give opiates.
Action
Anaesthetic agent.
Preparations
A mixture of 50% nitrous oxide and 50% oxygen in a blue cylinder with a white shoulder.
Indications
Acute pain.
Cautions
• Chest injuries
• Head injuries
• Cold weather
• Alcohol/drug intoxication
• Sickle cell crisis
• >50% oxygen indicated.
Contraindications
• Pneumothorax
• Gastrointestinal obstruction
• Recent diving activity
• Reduced Glasgow coma scale (GCS)
• Disturbed psychiatric patients.
Side-effects
• Decreased level of consciousness
• Nausea and vomiting
• Confusion ± distress.
Administration
Inhalation via demand valve with onset of action within 3–5 minutes.
Dose
As required to relieve pain.
Epinephrine (adrenaline)
Epinephrine is a sympathomimetic drug which stimulates both a and β receptors. a receptor activity increases peripheral vascular resistance without constricting coronary and cerebral vessels. This raises systolic and diastolic pressures during CPR, which makes CPR more effective; β receptor activity increases myocardial contractility in cardiac arrest and relieves bronchospasm in acute severe asthma. Epinephrine also reverses the allergic manifestations of acute anaphylaxis. If epinephrine has already been self-administered by the patient (e.g. EpiPen 0.3 mg for adults or 0.15 mg for children), this should be taken into account when determining the timing and dosage for administration.
Main prehospital use
• Cardiac arrest
• Acute anaphylaxis
• Life threatening asthma with failing ventilation and continued deterioration despite nebuliser therapy.
Other uses
Nebulised in severe croup.
Action
• Increases heart rate
• Increases blood pressure
• Increases myocardial contraction force
• Bronchodilation
• Vasoconstriction.
Preparations
• 10 mL disposable syringe with 0.1 mg/mL (1:10 000)
• 1 mL disposable syringe or ampoule with 1 mg/mL (1:1000).
Indications
• Cardiac arrest
• Acute anaphylaxis
• Severe croup.
Cautions
Hypothermia (give single dose only).
Contraindications
None in cardiac arrest.
Side-effects
• Tachycardia
• Angina and arrhythmias
• Hypertension
• Anxiety
• Headache.
Administration
• IV, IM, intraosseous, nebulised or subcutaneous
• IV administration is far better in cardiac arrest
• IM administration should be used in anaphylaxis.
Dose
• In cardiac arrest, 1 mg (10 mL of 1:10 000) every 3–5 minutes
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